WO2011121672A1 - Node device and data transmission method - Google Patents

Abstract

A node device is provided with a backtrack unit for transmitting part of target data including at least the data identification information of the target data to the origin adjacent node device of the target data when the target data transmitted earlier has returned, and when an adjacent node device which is capable of transmitting the target data is not found among a plurality of the adjacent node devices.

Description

Node device and data transmission method

The present invention relates to a node device used in a network including a plurality of node devices and a data transmission method.

An ad hoc network has been put to practical use as one form of a network including a plurality of node devices. In an ad hoc network, autonomous path selection is performed in each node device. That is, each node device of the ad hoc network has a function of operating as a router or a switch. Here, each node device can recognize the surrounding network configuration by exchanging messages and the like with adjacent node devices. Therefore, when an ad hoc (particularly, wireless ad hoc) method is employed, a desired network can be constructed simply by placing a node device in an environment where the network is to be constructed without providing a management device for managing the entire network. Furthermore, in an ad hoc network, it is easy to add or delete node devices, and the network configuration can be easily changed.

However, in an ad hoc network, since each node device autonomously selects a route, an optimal route is not necessarily selected. That is, in an ad hoc network, the efficiency of data transfer may be poor. For this reason, improvement in data transfer efficiency in ad hoc networks is required.

As related technologies, processing to return a dummy connection establishment response in response to a connection request and processing to return a dummy transmission data reception response (ACK) when transmission data is received in order to improve the processing time of the transmission side And a process for temporarily storing transmission data in the transmission data buffer and a process for establishing the connection and transmitting to the other party when there is transmission data in the transmission data buffer. . (For example, Patent Document 1)

Japanese Patent Laid-Open No. 11-4259

An object of the present invention is to improve data transfer efficiency in a network in which route selection is autonomously performed by each node device.

The node device according to one aspect of the present invention includes a reception unit, a first storage unit, a second storage unit, an update unit, a transmission unit, and a backtrack unit. The receiving means receives data from one of the plurality of adjacent node devices. The first storage means includes data identification information for identifying transmission target data, and transmission destination adjacent node identification information for identifying a transmission destination adjacent node device that is a transmission destination of the transmission target data among the plurality of adjacent node devices. And origin node identification information for identifying the origin neighboring node device that is the neighboring node device that has transmitted the transmission target data first. The second storage means stores transmission possibility information indicating the transmission possibility of data to the final destination for each of the plurality of adjacent node identification information in association with the final destination of data. The updating means transmits the transmission data associated with the data identification information based on the fact that the data identification information for identifying the data received by the receiving means is stored as the data identification information in the first storage means. Identifying the adjacent node identification information, and in the second storage means, of the transmission possibility information of the adjacent node associated with the final destination set in the received data, the specified adjacent node identification information Update sendability to not send. The transmission means selects an adjacent node device that can be transmitted based on the transmission possibility information of the transmission destination adjacent node identification information associated with the final destination of the received data in the second storage means, and selects the selection The received data is transmitted to the adjacent node device. The backtrack means, based on the fact that all the transmission possibility information of the transmission destination adjacent node identification information associated with the final destination of the reception data in the second storage means cannot be transmitted, The means transmits a part of the received data including at least the data identification information of the received data to the origin adjacent node device associated with the received data identification information.

A node device according to another aspect of the present invention includes a reception unit, a first storage unit, a second storage unit, an update unit, a transmission unit, and a data holding unit. The receiving means receives data from one of the plurality of adjacent node devices. The first storage means includes data identification information for identifying transmission target data, and transmission destination adjacent node identification information for identifying a transmission destination adjacent node device that is a transmission destination of the transmission target data among the plurality of adjacent node devices. And origin node identification information for identifying the origin neighboring node device that is the neighboring node device that has transmitted the transmission target data first. The second storage means stores transmission possibility information indicating the transmission possibility to each of the plurality of adjacent node devices in association with the final destination of the data. The updating means transmits the transmission data associated with the data identification information when the received data identification information for identifying the received data received by the receiving means is stored as the data identification information in the first storage means. Identifying the adjacent node identification information, and in the second storage means, of the transmission possibility information of the adjacent node associated with the final destination set in the received data, the specified adjacent node identification information Update sendability to not send. The transmission means selects an adjacent node device that can be transmitted based on the transmission possibility information of the transmission destination adjacent node identification information associated with the final destination of the received data in the second storage means, and selects the selection Data is transmitted to the adjacent node device. The data holding unit holds data including data identification information transmitted from the transmission unit to the adjacent node device. The transmission means receives data from the data holding means based on the reception means receiving at least a part of the data including the data identification information of the data transmitted by the own node apparatus from the destination adjacent node apparatus. Is extracted and the data is transmitted.

According to the configuration or method of the embodiment, data transfer efficiency is improved in a network in which route selection is autonomously performed by each node device.

It is a figure which shows the 1st example of a network structure. It is a figure which shows the 2nd example of a network configuration. It is a functional block diagram which shows the structure of the node apparatus in 1st Embodiment. It is a figure which shows the hardware constitutions of the node apparatus in 1st Embodiment. It is a figure explaining weight learning paying attention to one node apparatus. It is a figure explaining a mode that a path | route is selected dynamically and autonomously distributed in the network of FIG. It is a figure which shows the example of a flame | frame. It is a figure which shows the example of the data stored in the buffer part of FIG. It is a figure which shows the example of the adjacent node management table of FIG. It is a figure which shows the example of the weighting table of FIG. It is a figure explaining the change of the weighting table of FIG. FIG. 6 is a diagram (part 1) illustrating an example of an FID management table in FIG. 3; FIG. 6 is a diagram (part 2) illustrating an example of the FID management table of FIG. 3; It is a figure which shows backtrack operation | movement typically. FIG. 15 is a sequence diagram illustrating a backtrack operation illustrated in FIG. 14. It is an Example of a FID management table. It is a figure which shows the format of the flame | frame used by backtracking. It is a figure explaining aggregation of an empty data frame. It is a flowchart which shows operation | movement of the node apparatus which performs backtracking. It is an Example of a transmission queue. It is a flowchart (the 1) which shows empty data frame aggregation processing. It is a flowchart (the 2) which shows empty data frame aggregation processing. It is a flowchart which shows the reception process of an empty data frame. It is a flowchart of a frame reception process. It is a flowchart of a hello frame reception process. It is a flowchart of a hello frame transmission process. It is a flowchart of the aging process of an adjacent node management table. It is a flowchart of the aging process of a weighting table. It is a flowchart of the aging process of a FID management table. It is a flowchart (the 1) of a data frame reception process. It is a flowchart (the 2) of a data frame reception process. It is a flowchart (the 3) of a data frame reception process. It is a flowchart which shows another Example of the procedure shown in FIG. It is a flowchart (the 4) of a data frame reception process. It is a flowchart (the 5) of a data frame reception process. It is a flowchart of the weighting table adjustment process in step S812a of FIG. It is a flowchart of an ACK frame reception process. It is a flowchart which shows a process when an ACK frame is not received by timeout time. It is a flowchart (the 1) of the transmission process in case a node apparatus becomes GS and transmits a data frame. It is a flowchart (the 2) of the transmission process in case a node apparatus becomes GS and transmits a data frame. 36 is a flowchart of processing performed by a node device that can also be a GS in place of the processing of FIGS. 34 to 35 as part of data frame reception processing. FIG. 7 is a timing chart showing recognition of adjacent nodes by transmission / reception of a hello frame and route selection of FIG. It is a figure which shows the example of the wired network to which 2nd Embodiment is applied. It is a figure which shows the example of the adjacent node management table in 2nd Embodiment.

Hereinafter, embodiments of the invention will be described with reference to the drawings. Specifically, first, the configuration of the network according to the embodiment and the configuration of each node device will be described. Next, an outline of a method for improving the efficiency of data transfer will be described. Further, the operation of each node device will be described in detail with reference to the flowchart. Thereafter, another embodiment will be described.

FIG. 1 is a diagram showing a first example of a network configuration. A network 1 in FIG. 1 is an example of an ad hoc network to which the following embodiments can be applied, and includes a plurality of node devices. Hereinafter, in the description from the viewpoint of the network topology, the “node device” may be simply referred to as “node”.

Identification information unique to the network 1 (hereinafter referred to as “node ID (identification)”) is assigned in advance to each node device in the network 1. In the following, it is assumed that the reference symbol “N _i ” indicates a node ID. For example, a node device to which N _i is assigned as a node ID is referred to as “node device N _i ”. In the following, the node device N to N _i is a node ID assigned to itself for _i, the node device N _i is also referred to as "own node ID" (Figure 1, 1 ≦ i ≦ 7).

In FIG. 1, links are indicated by solid lines. Specifically, the topology of the network 1 is as follows. That is, between the node devices N ₁ and N ₂ , between the node devices N ₂ and N ₃ , between the node devices N ₂ and N ₆ , between the node devices N ₃ and N ₄ , and between the node devices N ₃ and N ₅ There are links between the node devices N ₄ and N ₅ , between the node devices N ₄ and N ₇ , and between the node devices N ₆ and N ₇ .

In the following, the “link” may be a wireless link or a wired link. When the node devices N _i and N _j can communicate information directly and wirelessly without being relayed by other node devices N _k , “there is a wireless link between the node devices N _i and N _j. (In FIG. 1, 1 ≦ i, j, k ≦ 7). Further, when the node devices N _i and N _j are directly connected by a cable and the node devices N _i and N _j can communicate information via the cable, the node devices N _i and N _j There is a wired link between them. "

In addition, when a wireless or wired link exists between the node devices N _i and N _j , it is said that “the node devices N _i and N _j are adjacent to each other”. In other words, for the node device N _i , the node device N _j is an adjacent node device, and for the node device N _j , the node device N _i is an adjacent node device.

Note that a new node device may be added to the network 1 in FIG. 1, or any _{one of} the node devices N ₁ to N ₇ may be removed and disappear from the network 1. Also, links are not fixed and can change dynamically.

For example, a new wireless link may be established between the node devices N _i and N _j due to the influence of weather, shielding, or the like, or the wireless link established so far may be lost. If the node device is movable, the presence or absence of a link may change due to a change in the distance between the node devices. Further, by changing the connection of the cable, a new wired link may be established, or the existing wired link may disappear, and the wired link may disappear due to a failure such as cable disconnection.

According to each embodiment described below, even in an environment where nodes and links dynamically change in this way, an appropriate route that can be used depends on the situation of the network 1 at the time when data is transmitted. Data is transmitted while being found and selected dynamically. In addition, the route selection according to the dynamic topology change is realized in an autonomous and distributed manner without the node devices N ₁ to N ₇ needing to recognize the topology of the entire network 1 that dynamically changes.

By the way, as will be described in detail later with reference to FIG. 7, in the following, PDU (Protocol Data Unit) that is a unit of data transmitted and received between node devices according to a communication procedure (protocol), and unit data of transmission / reception itself are referred to as “frame”. Called. Data transmission / reception in the network 1 is performed using a frame. The first transmission source node device in the network 1 is hereinafter referred to as “GS (Global Source)”, and the frame destination node device. Is referred to as “GD (Global Destination)” hereinafter.

For example, when the node device N ₁ is GS and the node device N ₇ is GD, since the node devices N ₁ and N ₇ are not adjacent in the network 1, the frame is relayed by other node devices, and as a result, the frame it reaches the node device _{N 7.} For example, the frame may be transmitted from the node device N ₁ to the node device N ₂ , transmitted from the node device N ₂ to the node device N _6, and transmitted from the node device N ₆ to the node device N ₇ . Hereinafter, the route is represented by a tuple such as <N ₁ , N ₂ , N ₆ , N ₇ >.

In the example of the path <N ₁ , N ₂ , N ₆ , N ₇ >, for example, when a frame is transmitted from the node device N ₁ to the node device N ₂ , the final destination of the frame is the node device N that is GD. ₇ But direct destination of the frame is the node device N ₂ adjacent to the node device N _1. In the following, in transmitting a frame between two adjacent node devices in this way, the node device that is the transmission source of the frame is referred to as “LS (Local Source)”, and the node device that is the destination of the frame is referred to as “LD (Local). Destination) ”. For example, as described above, the LS and LD when the frame is relayed from the node device N ₁ to the node device N ₇ via the node devices N ₂ and N ₆ are as follows.

From the node device _{N 1} that is also GS, to the node device _{N 2} adjacent to the node device _{N 1,} when the first frame is transmitted, LS is a node device _{N 1,} LD is the node device _{N 2.} Then, from the node device _{N 2,} to the node device _{N 6} adjacent to the node apparatus _{N 2,} When a frame is transmitted, LS is a node device _{N 2,} LD is the node device _{N 6.} When the from the node device _{N 6,} the frame is transmitted to the node device _{N 7,} which is also GD is adjacent to the node device _{N 6,} LS is a node device _{N 6,} LD is the node device _{N 7} .

Note that one or a plurality of node devices in the network 1 may be connected to a network device (not shown) belonging to a network different from the network 1 (hereinafter referred to as “external network”).

For example, the gateway device of the external network including a data management server, the node device N ₇ may be connected by a wired link or a wireless link. Then, the data transmitted in the network 1 with the node device N ₇ designated as GD may be transmitted from the node device N ₇ to the data management server via the gateway device and managed by the data management server.

Next, another network example will be described with reference to FIG. FIG. 2 is a diagram illustrating a second example of the network configuration. The network 2 in FIG. 2 is also an example of an ad hoc network to which the following embodiments can be applied, and includes a plurality of node devices. Further, similarly to the network 1 of FIG. 1, the network 2 may be connected to an external network (not shown).

The network 2 includes node devices N ₁₀₁ to N ₁₂₀ . FIG. 2 is a diagram expressed by paying attention to one node device N ₁₀₅ among the node devices N ₁₀₁ to N ₁₂₀ . That is, the node device N ₁₀₅ indicated by a thick solid line circle only needs to recognize the existence of the three adjacent node devices N ₁₀₇ , N ₁₁₁ , and N ₁₁₂ that can directly communicate with each other and the node ID. It is not necessary to recognize the topology of the entire network 2. Node device N ₁₀₅ is far from the network 2 topologies, neither need to be aware of the number of node devices in the network 2, also need to be preliminarily know the node ID of the node device that is not adjacent to the node device N ₁₀₅ Absent.

In FIG. 2, a portion recognized by the node device N ₁₀₅ is represented by a solid line, and a portion that the node device N ₁₀₅ does not need to recognize is represented by a broken line. That is, in FIG. 2, only the following items existing within the range of the hop number 1 as viewed from the node device N ₁₀₅ are shown by solid lines.
Node device N ₁₀₅ itself. Three node devices N ₁₀₇ , N ₁₁₁ , and N ₁₁₂ adjacent to the node device N _105.
Three links connecting node device N ₁₀₅ to three adjacent node devices N ₁₀₇ , N ₁₁₁ , and N ₁₁₂ , respectively

According to each embodiment described below, each node device in the network only needs to recognize an adjacent node device like the node device N ₁₀₅ described above. Therefore, even if the scale of the network increases, “each node device communicates control information to recognize the network topology, and the communication of the control information increases the load on the network, which deteriorates the overall performance of the communication system. It does not fall into the situation.

FIG. 3 is a functional block diagram showing the configuration of the node device in the first embodiment. Specifically, each node device in FIG. 1 or 2 corresponds to, for example, the node device 100 shown in FIG.

The node device 100 includes a receiving unit 101 that receives a frame and a transmitting unit 102 that transmits a frame. The node device 100 also includes an adjacent node management table 103, a weighting table 104, and an FID (Frame IDentification) management table 105 in order to store various types of information used for frame transmission.

The node device 100 further includes a frame branching processing unit 106 that determines the type of frame received by the receiving unit 101. In the first embodiment, “data frame”, “hello frame”, and “ACK (ACKnowledgment) frame” are used. Also, “empty data frame” is used in order to increase the frame transfer efficiency. Furthermore, an “aggregated empty data frame” is also used as necessary.

The node device 100 includes an ACK processing unit 107 that performs processing related to an ACK frame, and a link management unit 108 that performs processing in response to reception of a hello frame. Further, the node device 100 includes a buffer unit 109 and a data frame processing unit 110 in order to perform processing according to reception of the data frame. The node device 100 further includes an upper layer processing unit 111, a hello frame generation unit 112, and an FID generation unit 113. Further, the node device 100 includes a transmission queue 114.

Each unit of the node device 100 operates as follows.
The receiving unit 101 receives the frame and outputs the received frame to the frame branch processing unit 106. Then, the frame branch processing unit 106 determines the type of frame.

When the hello frame is received, the frame branching processing unit 106 outputs the received hello frame to the link management unit 108. The link management unit 108 manages the adjacent node management table 103 and is also involved in the management of the weighting table 104.

Here, the hello frame is a type of control frame for communicating control information, and specifically, a frame for the node device 100 to notify the other node devices of its own existence. Therefore, as will be described in detail later with reference to FIG. 25, the link management unit 108 recognizes the presence of the adjacent node device triggered by the reception of the hello frame, and reflects the recognition result in the adjacent node management table 103. That is, the adjacent node management table 103 is a table for the node device 100 to store other node devices adjacent to the node device 100.

Since the network status can change dynamically, in some cases, other node devices that have been recognized as adjacent node devices by the link management unit 108 may become unrecognizable as adjacent node devices. . Therefore, as will be described in detail later with reference to FIG. 27, the link management unit 108 also performs an aging process for deleting, from the adjacent node management table 103, entries related to node devices that have become unrecognizable as adjacent node devices.

In the first embodiment, the link management unit 108 adds, deletes, or updates the weighting table 104 in accordance with the change of the adjacent node device.
Here, the weighting table 104 is a table for managing, for each GD, information for determining which adjacent node device the frame is transmitted to. FIG. 3 shows weighting tables 104-1 to 104-M provided for each of the M GDs. In this specification, the “weighting table 104” is a general term for the weighting tables 104-1 to 104-M. In addition, when the operation of the node device 100 is started, the weighting table 104 does not exist and M = 0.

Specifically, the weighting table 104 manages, for each GD, “which adjacent node device can be selected as the LD by the node device 100 itself in order to finally reach the frame to the GD”. is doing. In other words, the weighting table 104 represents, for each GD of a frame, the priority at the time of selecting as an LD for one or more node devices adjacent to the node device 100 as a weight.

From another point of view, the fact that a certain adjacent node device is “selectable as an LD” means that the transmission possibility of a frame to the adjacent node device is “transmittable”. Also, that an adjacent node device is “not selectable as an LD” means that the transmission possibility of a frame to the adjacent node device is “not transmittable”, and the priority of the adjacent node device is It means a predetermined lowest priority corresponding to “transmission impossible”.

Therefore, when the adjacent node device of the node device 100 changes according to the change in the network status, the link management unit 108 performs the weighting table 104 according to the change of the adjacent node device, as will be described in detail later with reference to FIGS. Add, update, or delete.

Further, when an ACK frame is received, the frame branching processing unit 106 outputs the received ACK frame to the ACK processing unit 107. Here, the ACK frame is a kind of control frame, and is a frame for notifying the node device 100 of the reception of the data frame from the node device that is the LD of the data frame transmitted by the node device 100.

Therefore, the reception of the ACK frame means that the transmission of the data frame has succeeded, and the time-out without receiving the ACK frame even after a predetermined time has passed means that the transmission of the data frame has failed. means. The ACK processing unit 107 performs time-out monitoring of ACK frame reception shown in FIG.

The buffer unit 109 stores data frames in preparation for transmission failure and retransmission of data frames. Therefore, as will be described in detail later with reference to FIG. 37, when the ACK processing unit 107 recognizes the successful transmission of the data frame triggered by the reception of the ACK frame, the ACK processing unit 107 enters a state in which the unnecessary data frame can be deleted from the buffer unit 109. . However, in the buffer unit 109, the data frame is not brought into a state in which it can be immediately deleted when the corresponding ACK frame is received. That is, even when the corresponding ACK frame is received, the data frame written in the buffer unit 109 is held as it is until the predetermined time G elapses. Although the predetermined time G will be described in detail later, for example, it corresponds to the aging time of the FID management table 105. Further, the ACK processing unit 107 notifies the data frame processing unit 110 of success or failure of transmission of the data frame.

When a data frame is received, the frame branching processing unit 106 stores the received data frame in the buffer unit 109 and requests the data frame processing unit 110 to perform the processes shown in FIGS. 30 to 35 described later. To do.

Here, the data frame is a frame including, as a payload, data that the node device that is the GS intends to transmit to the node device that is the GD. In other words, a PDU of a protocol defined in a layer higher than a layer in which the frame in the first embodiment is defined is included in the data frame as a payload. When the node device 100 is GS or GD, the upper layer processing unit 111 processes an upper layer PDU included as a payload in the data frame.

An outline of the operation of the data frame processing unit 110 that has received a data frame processing request from the frame branching processing unit 106 is as follows.
The data frame processing unit 110 requests the transmission unit 102 to transmit an ACK frame for the data frame received by the reception unit 101. Further, the data frame processing unit 110 determines whether or not the GD value of the received data frame is equal to the own node ID of the node device 100. If the GD value of the received data frame is different from the own node ID of the node device 100, the data frame processing unit 110 refers to the FID management table 105, so that the current reception is (A1) and ( It is determined which of A2) is applicable.

(A1) A data frame transmitted in the past by the node device 100 as an LS returned to the node device 100 while being relayed through the network, and was received by the receiving unit 101.

(A2) A new data frame other than (A1) is received by the receiving unit 101.
If the data frame processing unit 110 determines that the current reception corresponds to (A2), the data frame processing unit 110 refers to the weighting table 104, selects an adjacent node device designated as an LD to transfer the received data frame, Is requested to the transmission unit 102.

On the other hand, when determining that the current reception corresponds to (A1), the data frame processing unit 110 recognizes that the adjacent node device selected as the LD in the past is not an appropriate LD, and stores the recognition result in the weighting table 104. To reflect. Then, the data frame processing unit 110 refers to the weighting table 104 to determine whether or not there are other adjacent node devices that can be selected as the LD.

The data frame processing unit 110 also receives a notification of data frame transmission success or transmission failure from the ACK processing unit 107 and recognizes whether or not the adjacent node device selected as the LD of the data frame is appropriate. The result is reflected in the weighting table 104.

Incidentally, adjacent to the node device 100, and a node device N _i is "can be selected as the LD", it is intuitively try to select "adjacent node device N _i as LD, GD frame successfully It ’s worth trying to see if it ’s possible. Specifically, the node device _Ni being “selectable as an LD” means “not (B1) below or (B2) below”. The more detailed meaning of the word “selectable” is clear from the description of FIG. 5 described later and the descriptions of (F1) to (F2) and (G1) to (G4) regarding FIG.

(B1) results node device 100 has selected as the LD to the adjacent node device N _i in the past, sometimes some failures of the loop or the like occurs, already proven to "node device N _i is inappropriate as LD" ing.

The (B2) This receiver 101 is a data frame received once LS when the receiver 101 is received for the first time (hereinafter referred to as "Original Local Source" abbreviated as "OLS") was the node device N _i .

If there are still other adjacent node devices that can be selected as the LD, the data frame processing unit 110 selects the selectable adjacent node device as the LD, and requests the transmission unit 102 to transfer the data frame. . Conversely, if there are no more adjacent node devices that can be selected as the LD, the data frame processing unit 110 operates as in (C1) or (C2) below.

(C1) When the GS of the data frame received this time is other than the node device 100, the data frame processing unit 110 selects the OLS as the LD to return the data frame to the OLS, and transfers the data frame to the transmission unit 102. To ask. This operation is an operation for causing an adjacent node device that is an OLS to recognize that “selecting the node device 100 as an LD is inappropriate”, and corresponds to backtracking in a route search as described later.

(C2) When the GS of the data frame received this time is the node device 100 itself, the upper layer processing unit 111 originally generated the data frame. Therefore, the data frame processing unit 110 notifies the upper layer processing unit 111 of a data frame transmission failure, and discards the data frame stored in the buffer unit 109.

In order to realize the operation of the data frame processing unit 110 as described above, the data frame processing unit 110 needs to distinguish between (A1) and (A2). Therefore, in the first embodiment, frame identification information that can uniquely identify a data frame is included in each data frame, and the FID management table 105 stores the frame identification information.

The frame identification information in the first embodiment is specifically a combination of the node ID of the node device, which is the GS of the data frame, and the FID. The FID is identification information that uniquely identifies each of a plurality of frames transmitted as a GS by a certain node device, and may be a sequence number of a predetermined number of bits or a time stamp, for example.

That is, since each node device independently generates a FID, a plurality of different node devices may accidentally generate the same FID. However, the frame identification information is not a FID alone, but a combination of the node ID of the node device, which is the GS of the data frame, and the FID. The node ID is information for uniquely identifying the node device in the network as described above. Therefore, even if a plurality of different node devices accidentally generate the same FID, frames transmitted by different node devices as GS each have different frame identification information and can be distinguished.

The frame identification information is not rewritten by the node device that relays the data frame even if the data frame is transferred through the network via one or more node devices, and therefore does not change. The data frame processing unit 110 records the frame identification information of the data frame requested to be transmitted to the transmission unit 102 in the FID management table 105, and when the data frame later returns to the node device 100 itself (A1) It can be recognized that it falls under.

Note that the node device 100 performs other processing not triggered by reception of the frame. Specifically, the hello frame generation unit 112 periodically generates a hello frame using the FID generated by the FID generation unit 113 and outputs the hello frame to the transmission unit 102. Then, since the transmission unit 102 transmits a hello frame, the node device 100 can periodically notify the surroundings of the presence of the node device 100 itself.

Also, the upper layer processing unit 111 can output the data to be transmitted as a payload in the data frame to the data frame processing unit 110 at an arbitrary timing. Then, the data frame processing unit 110 generates a data frame in response to a request from the higher layer processing unit 111 and instructs the transmission unit 102 to transmit the data frame. Thus, the node device 100 can be a GS itself.

FIG. 4 is a diagram illustrating a hardware configuration of the node device according to the first embodiment. The node device 100 in FIG. 3 may be realized by, for example, various hardware illustrated in FIG.
In the example of FIG. 4, the node device 100 includes an MPU (MicroProcessing Unit) 201, a PHY (PHYsical layer) chip 202, and a timer IC (Integrated Circuit) 203. Further, the node device 100 includes a dynamic random access memory (DRAM) 204, a flash memory 205, and a wireless module 206.

A communication interface that connects the MPU 201 and the PHY chip 202 is an MII / MDIO (Media Independent Interface or Management Data Input / Output) 207. Both MII and MDIO are interfaces between the physical layer and the MAC sublayer (Media Access Control sublayer). The MPU 201 and the timer IC 203 are connected via an I ² C / PIO (Inter-Integrated Circuit or Parallel Input / Output) bus 208. The DRAM 204, the flash memory 205, and the wireless module 206 are connected to the MPU 201 via a PCI (Peripheral Component Interconnect) bus 209.

The MPU 201 loads a program such as firmware stored in a flash memory 205, which is a kind of nonvolatile storage device, into the DRAM 204, and executes various processes while using the DRAM 204 as a working memory. The MPU 201 executes the program so that the frame branch processing unit 106, the ACK processing unit 107, the link management unit 108, the data frame processing unit 110, the upper layer processing unit 111, the hello frame generation unit 112, and the FID generation in FIG. The unit 113 can operate.

Note that a program such as firmware may be provided by being stored in a computer-readable storage medium and installed in the node device 100. Alternatively, the program may be downloaded from the network via the PHY chip 202 or the wireless module 206 and installed in the node device 100.

Depending on the embodiment, other types of storage devices other than the DRAM 204 and the flash memory 205 may be used. For example, the node device 100 may include a storage device such as a CAM (Content Addressable Memory), an SRAM (Static Random Access Memory), or an SDRAM (Synchronous Dynamic Random Access Memory).

3, the adjacent node management table 103, the weighting table 104, the FID management table 105, the buffer unit 109, and the transmission queue 114 are realized by the DRAM 204, the flash memory 205, or other storage device (not shown). The flash memory 205 stores not only programs but also information unique to the node device 100 such as the node ID of the node device 100.

The PHY chip 202 is a circuit that performs physical layer processing in wired connection. Since the first embodiment is applied to a wireless network, the node device 100 may not include the PHY chip 202 in the first embodiment. However, the node device 100 may include a PHY chip 202 for connection between the node device 100 and an external network.

For example, the node device 100 may include a wired LAN port according to the Ethernet (registered trademark) standard, and may be connected to a gateway device of an external network via a cable connected to the wired LAN port.

In that case, the MPU 201 can generate an Ethernet frame and output it to the PHY chip 202 via the MII / MDIO 207. The PHY chip 202 converts the output from the MPU 201 (that is, a logical signal representing an Ethernet frame) into a signal (that is, an electrical signal or an optical signal) corresponding to the type of the cable, and outputs the signal to the cable. In this way, the node device 100 can transmit data to the external network using the PHY chip 202.

The PHY chip 202 can also convert an electrical signal or an optical signal input from an external network via a cable and a wired LAN port into a logical signal and output the logical signal to the MPU 201 via the MII / MDIO 207. Thus, the node device 100 can receive data from the external network using the PHY chip 202.

The wireless module 206 is hardware that performs physical layer processing in wireless connection. The wireless module 206 includes, for example, an antenna, an ADC (Analog-to-Digital Converter), a DAC (Digital-to-Analog Converter), a modulator, a demodulator, an encoder, a decoder, and the like.

In the first embodiment, the receiving unit 101 and the transmitting unit 102 in FIG. 3 are realized by the wireless module 206 in FIG. That is, in the first embodiment, the link in the network is a wireless link. Note that an embodiment in which a wired link is present is also possible, as in a second embodiment to be described later.

Timer IC 203 performs a count-up operation until a set time elapses, and outputs an interrupt signal when the set time elapses. For example, the timer IC 203 may output an interrupt signal for executing the aging processing of the adjacent node management table 103, the weighting table 104, and the FID management table 105 at predetermined intervals.

Depending on the embodiment, the hardware configuration of the node device may be different from that in FIG. 4, and other hardware other than the standard / type illustrated in FIG. 4 may be used for the node device.

For example, the frame branch processing unit 106, the ACK processing unit 107, the link management unit 108, the data frame processing unit 110, the upper layer processing unit 111, the hello frame generation unit 112, or the FID generation unit 113 in FIG. It may be realized. Specifically, each part of FIG. 3 may be realized by a reconfigurable circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) instead of the MPU 201. Of course, each unit of FIG. 3 may be realized by both the MPU 201 and the hardware circuit.

In the following description, for the sake of clarification, a reference code in which a node ID is added after a reference code of each part in FIGS. 3 and 4 may be used. For example, the adjacent node management table 103 of FIG. 3 included in the node device N ₁ may be referred to with a reference numeral “103-N ₁ ”.

Subsequently, an outline of the operation of each node device will be described with reference to FIG. 5, and route selection realized as the entire network as a result of the operation of each node device will be described with reference to FIG.

FIG. 5 is a diagram for explaining learning of weights by paying attention to one node device. In FIG. 5, six node devices in the network 3 are extracted as “node α” to “node ζ”. As shown in FIG. 5, nodes α, γ, δ, ε, and ζ are adjacent to the node β, and the following five links are indicated by solid lines in FIG. 5.
-Link L _{β, α} between nodes β and _α
Link L _{β, γ} between nodes β and _γ
Link L _{β, δ} between nodes β and _δ
Link L _{β, ε} between nodes β and _ε
Link L _{β, ζ} between nodes β and _ζ

Further, the network 3 a schematically represented in the shape of a cloud in FIG. 5 is a part of the network 3. Specifically, the network 3a includes a link directly connecting the nodes δ and ζ, or one of the nodes δ and ζ via one or more unillustrated nodes and two or more unillustrated links. Includes routes that indirectly connect each other.

In the following, focusing on the node β in FIG. 5, the learning of the weight at the node β will be described.
At some point, the node β receives a data frame 301 having a node (not shown) in the network 3 (hereinafter referred to as “node η” for convenience) as a GD from the node α via the links L _{β and α.} . The node β has the weighting table 104 in FIG. 3, and among these, the weighting table corresponding to the node η is referred to by the reference numeral “104-h” for convenience in the description of FIG.

Although details will be described later with reference to FIGS. 10 and 11, each of the weighting tables 104 managed for each GD stores associations between adjacent nodes and weights. Since nodes α, γ, δ, ε, and ζ are adjacent to the node β, in the weighting table 104-h, the node α and the weight W _α , the node γ and the weight W _γ , the node δ and the weight W _δ , The node ε and the weight W _ε are associated with the node ζ and the weight W _ζ , respectively.

For convenience of explanation, it is assumed that the weighting relationship at the time when the node β receives the data frame 301 from the node α is as shown in Expression (1).
W _γ <W _δ <W _ε <W _ζ (1)
Hereinafter, in the first embodiment, for convenience of explanation, the weight takes a value of 0 or more and 1 or less, and the smaller the weight value, the higher the priority of the node corresponding to the weight.

Therefore, based on the equation (1), the node β recognizes that the priority of the node γ associated with the lightest weight W _γ is the highest among the adjacent nodes γ, δ, ε, and ζ. Therefore, the node β first selects the node γ from the adjacent nodes γ, δ, ε, and ζ as the LD for transferring the data frame 301, and transmits the data frame 301 to the node γ.

Here, when transmission from the node β to the node γ fails, the node β learns that “it is inappropriate to select the node γ as an LD when transmitting a data frame having the node η as a GD”. As a result of learning, the node β decreases the priority of the node γ. That is, the node β increases the value of the weight W _γ .

There are several types of transmission failures. Specifically, the node β selects the node γ as the LD when transmitting the data frame with the node η as the GD as shown in (D1) or (D2) below. Is inappropriate. "

(D1) In the case of a link failure When the node β transfers the data frame 301 to the node _γ , if a failure occurs in the link L _{β, γ} or the node γ, the node β transmits to the node γ. Recognizes that failed.

For example, when the links L _{β and γ} are wireless links, if an ACK frame for the data frame 301 is not returned from the node γ within a predetermined time, the node β times out and “transmits the data frame 301 to the node γ”. ” Then, the node β learns that “it is inappropriate to select the node γ as an LD when transmitting a data frame with the node η as a GD”, and the weight W _γ associated with the node γ selected as the LD. Increase the value of.

Since the quality environment of the radio link is likely to change, the link failure may be resolved again. Therefore, in the first embodiment, the weight W _γ is not increased to a maximum value at a time when a link failure occurs, but is increased by a predetermined value. In this way, it is possible to prevent the LD from becoming inappropriate due to the occurrence of a single link failure.

(D2) When the data frame 301 returns from the node γ to the node β The node β once succeeds in transmitting the data frame 301 to the node γ. For example, the node β recognizes that the transmission of the data frame 301 to the node γ is successful by receiving an ACK frame for the data frame 301 from the node γ. Therefore, the node β temporarily decreases the value of the weight W _γ associated with the node γ selected as the LD.

However, if a route that can transfer the data frame 301 from the node γ to the node η is not found in the network 3 thereafter, the node γ sends the data frame 301 back to the node β by a backtrack operation described later. For example, when the node γ is adjacent only to the node β, the node γ cannot find a path through which the data frame 301 can be transferred to the node η. Even when the node γ is adjacent to some nodes other than the node β, the node γ may not reach the node η depending on the topology of the network 3.

When the node γ performs the backtracking operation, the node β recognizes that “the transmission to the node γ has failed” because the node β itself receives the data frame 301 previously transmitted to the node γ from the node γ. Can do. As a result of recognition, the node β learns that “it is inappropriate to select the node γ as an LD when transmitting a data frame having the node η as a GD”, and the weight associated with the node γ selected as the LD. _Increase the value of Wγ.

In the first embodiment, as shown in (D2), when the node β recognizes a transmission failure by receiving the data frame 301 transmitted by the node β itself in the past, the node β specifically has the weight W _γ . Set the value to the maximum value.

Hereinafter, for convenience of explanation, it is assumed that the node β recognizes the transmission failure and sets the value of the weight W _γ to the maximum value as in (D2) in the example of FIG. As a result, Expression (2) is established.
W _δ <W _ε <W _ζ <W _γ (2)
Subsequently, in order to make the data frame 301 reach the node η (not shown) that is a GD, the node β selects an adjacent node other than the node γ determined to be inappropriate as the LD, and tries to retransmit the data frame 301. Specifically, based on Expression (2), the node β selects the node δ associated with the lightest weight W _δ at the present time as the LD, and transmits the data frame 301 to the node δ.

In the example of FIG. 5, the node β receives the ACK frame for the data frame 301 from the node δ, and the node β recognizes the successful transmission. When recognizing the successful transmission, the node β decreases the value of the weight W _δ associated with the node δ selected as the LD. As a result, the formula (2) is also established.

Subsequently, it is assumed that the data frame 301 reaches the node ζ from the node δ via the network 3a. Assume that the node ζ selects the node β as the LD.
Then, since the node β receives from the node ζ the data frame 301 that the node β itself has transmitted to the node δ in the past, it can be recognized that “the transmission to the node δ has failed due to the presence of the loop”. As a result of the recognition, the node β learns that “it is inappropriate to select the node δ as LD when transmitting a data frame with the node η as GD”, and increases the value of the weight W _δ .

Here, also when the node β receives the data frame 301 returned in a loop from the node ζ, “the node β recognizes a transmission failure by receiving the data frame 301 transmitted in the past by the node β itself”. This is the same as in the case of (D2) above. Therefore, the node β learns that “it is inappropriate to select the node δ as an LD when transmitting a data frame having the node η as a GD”, and the weight W _δ associated with the node δ selected as the LD. Set the value of to the maximum value. As a result, Expression (3) is established.
_Wε < _Wζ < _Wγ = _Wδ (3)
FIG. 5 shows Expression (3) as a new weighting relationship as a result of updating the weighting by receiving the same data frame 301 from the node ζ.

Subsequently, the node β selects an adjacent node other than the nodes γ and δ determined to be inappropriate as the LD in order to cause the data frame 301 to reach a node η (not shown) that is a GD, and tries to retransmit the data frame 301. . Specifically, based on Expression (3), the node β selects the node ε associated with the lightest weight W _ε at the present time as the LD, and transmits the data frame 301 to the node ε.

In the example of FIG. 5, the node β receives the ACK frame for the data frame 301 from the node ε, and the node β recognizes the successful transmission. When recognizing the success of transmission, the node β decreases the value of the weight W _ε associated with the node ε selected as the LD. As a result, equation (3) is also established.

Here, it is assumed that the data frame 301 is not returned from the node ε to the node β by backtracking. Further, it is assumed that the data frame 301 loops in the network 3 and is transmitted from any adjacent node of the node β to the node β and is not received by the node β.

Then, from equation (3), the node β receives the lightest weight Wε when it receives another data frame having the node η as GD from any of the adjacent nodes α, γ, δ, and ζ as in the data frame 301. The node ε associated with is preferentially selected as the LD.

FIG. 6 is a diagram for explaining how routes are selected dynamically and autonomously distributed in the network 1 of FIG. Specifically, FIG. 6 shows a state of route selection in the network 1 when the node device N ₁ becomes GS and transmits a data frame in which the node device N ₇ is designated as GD.

FIG. 6 shows a failure that occurs between the network 1 of FIG. 1 and the node devices N ₄ and N ₇ . Further, twelve thick arrows in FIG. 6 indicate that a data frame is transferred from GS (ie, node device N ₁ ) to GD (ie, node device N ₇ ) while a route is dynamically selected in network 1. To express.

In the following, among the weighting table _{104-N i} of the node device _{N i,} to be referred to by reference numeral as for convenience those corresponding to the node device _{N 7 "104-h i} -N i" ( 1 ≦ i ≦ 6).

In the description of FIG. 6, unless otherwise specified, it is assumed that the transmission of the data frame is successful and the ACK frame is returned, and the description of the ACK frame is omitted to simplify the description. A series of processing flow including the reply of the ACK frame will be described later with reference to FIG.

In step S101, the node device _{N 1} is a GS, select the node device _{N 2} adjacent to only the node device _{N 1} as LD, and transmits the data frame to the node device _{N 2.}
The node device _{N 2,} in addition to the node device _{N 1} is an LS of the transmitted data frame at step S101, the node device _{N 3} and _{N 6} are adjacent. Of the two adjacent node devices N ₃ and N ₆ , the node device N ₃ is associated with a lighter weight in the weighting table 104 -h ₂ -N ₂ .

Then, the node device _{N 2} in step S102, select the node device _{N 3} as LD for transferring the received data frame at step S101, it transmits the data frame to the node device _{N 3.}

To the node device _{N 3,} in addition to the node device _{N 2} is LS of the transmitted data frame at step S102, the node apparatus _{N 4} and _{N 5} are adjacent. Of the two adjacent node devices N ₄ and N ₅ , the node device N ₄ is associated with a lighter weight in the weighting table 104 -h ₃ -N ₃ .

Then, the node device _{N 3} in step S103, select the node device _{N 4} as a LD for transferring the received data frame at step S102, it transmits the data frame to the node apparatus _{N 4.}

The node device _{N 4,} in addition to the node device _{N 3} is an LS of the transmitted data frame at step S103, the node device _{N 5} and _{N 7} are adjacent. Of the two adjacent node devices N ₅ and N ₇ , the node device N ₇ is associated with a lighter weight in the weighting table 104 -h ₄ -N ₄ .

Then, the node device _{N 4} in step S104, as LD for transferring a data frame received in step S103, select the node device _{N 7} that is also GD, transmits the data frame to the node device _{N 7.}

However, as shown in FIG. 6, when the node device N ₄ transmits a data frame to the node device N ₇ , a failure has occurred in the link between the node devices N ₄ and N _7. Fail. That is, since the node device N ₄ does not receive an ACK frame from the node device N ₇ even after waiting for a predetermined time, the node device N ₄ times out and recognizes the transmission failure.

Incidentally, the node device N ₄ in step S104 corresponds to the failed node in the above (D1) to the transmission of the data frame to the node γ in Figure 5 beta. Therefore, the node device N ₄ updates the weighting table 104-h ₄ -N ₄ according to the transmission failure (specifically, the weight associated with the node device N ₇ which is the LD in the transmission in step S104). Increase the value).

Then, the node device N ₄ in step S105, the LD for transferring a data frame received in step S103, still select another adjacent node device N ₅ not tried, transmits the data frame to the node device N ₅ To do.

The node device N ₅ is the other node device N ₄ is LS of the transmitted data frame at step S105, only the node device N ₃ are adjacent.
Therefore, the node device _{N 5} in step S106, select the node device _{N 3} as LD for transferring the received data frame at step S105, it transmits the data frame to the node device _{N 3.}

Then, the node device N ₃ in step S106 recognizes that "the node device N ₃ itself has received the same data frame that was transmitted in step S103". In other words, the node device N ₃ in step S106 corresponds to a node β which has received the data frame has been loops 5 from the node zeta. Therefore, the node device N ₃ updates the weighting table 104-h ₃ -N ₃ in the same manner as in FIG. 5 (specifically, the weight associated with the node device N ₄ that is the LD of the transmission in step S103) To the maximum value).

Then, in step S107, the node device N ₃ determines from among adjacent node devices other than OLS (that is, the node device N ₂ that is the LS when the node device N _{3 first} receives the data frame in step S102). Look for things that you haven't tried as LD yet. Here, the adjacent node devices other than the OLS are the node devices N ₄ and N ₅ , and the node device N ₄ has been selected in step S103.

Therefore, the node device _{N 3} in step S107, select the node device _{N 5} unselected as LD, and transmits the data frame to the node device _{N 5.} In other words, the node device N ₃ in step S107 corresponds to a node β to transmit a data frame to the node node reselect the LD the epsilon epsilon in FIG.

Then, the node device N ₅ in step S107, recognized as a "node apparatus N ₅ itself has received the same data frame that was transmitted in step S106". In other words, the node device N ₅ in step S107 corresponds to the failed node as (D2) to transmit the data frame to the node γ in FIG 5 beta. Accordingly, the node device N ₅ updates the weighting table 104-h ₅ -N ₅ in the same manner as in FIG. 5 (specifically, the weight of the weight associated with the node device N3 that is the LD of the transmission in step S106). Set the value to the maximum).

For the node device N ₅ , the adjacent node device other than the OLS (that is, the node device N ₄ that is the LS when the node device N _{5 first} receives the data frame in step S 105) has already failed in transmission. only node device N ₃ found to. Therefore, there is no longer any adjacent node device that can be selected as the LD.

Thus the node device _{N 5} in step S108 sends back a data frame to the node device _{N 4} is OLS. Step S108 is a backtracking operation, the node device N ₅ by backtracking operation, in the transmission of data frames to a "node device N ₇ GD is the node device N ₅ previously path from its own dead end (dead end The) can be a tell the node device N ₄ that it is "turned.

Then, the node device N ₄ in step S108 recognizes a "node apparatus N ₄ itself has received the same data frame that was transmitted in step S105". That is, the node apparatus N ₄ in step S108 corresponds to the failed node as (D2) to transmit the data frame to the node γ in FIG 5 beta. Therefore, the node device N ₄ updates the weighting table 104-h ₄ -N ₄ in the same manner as in FIG. 5 (specifically, the weight associated with the node device N ₅ that is the LD of the transmission in step S105). To the maximum value).

However, although the node β that can be selected as the LD still remains in the node β in FIG. 5 even if the transmission of the data frame to the node γ fails, the node device N ₄ in step S108 in FIG. There is no adjacent node device that can be selected as an LD. That is, the two adjacent node devices N ₇ and N ₅ other than the OLS have already been selected as LDs in steps S104 and S105, respectively, and it has already been found that both result in transmission failure.

Therefore, the node device N4 in step S109 sends back a data frame to the node device _{N 3} is OLS. Step S109 is also backtracking operation, in the transmission of data frames to a "node device N ₇ and GD is the node device N ₄ is a node device N _3, ahead of the path from the node device N ₄ itself has become blind alley Can be informed.

Then, the node device N ₃ in step S109 recognizes that "the node device N ₃ itself has received the same data frame that was transmitted in step S107". That is, the node apparatus N ₄ in step S109 corresponds to a node β which has received the data frame has been loops 5 from the node zeta. Therefore, the node device N ₃ updates the weighting table 104-h ₃ -N ₃ in the same manner as in FIG. 5 (specifically, the weight associated with the node device N ₅ that is the LD of the transmission in step S107). To the maximum value).

However, although it has been found that transmission of the data frame to the node δ fails in the node β in FIG. 5, the node ε that can be selected as the LD still remains, but the node device N _{3 in} step S109 in FIG. Therefore, there are no adjacent node devices that can be selected as the LD. That is, the two adjacent node devices N ₄ and N ₅ other than the OLS have already been selected as LDs in steps S103 and S107, respectively, and it has already been found that both result in transmission failure.

Therefore, the node device _{N 3} in step S110 sends back a data frame to the node device _{N 2} is OLS. Step S110 is also a backtracking operation, and the node device N ₃ sends a message “the route ahead from the node device N ₃ itself to the node device N ₂ to send a data frame with the node device N ₇ as GD”. Can be informed.

Then, the node device N ₂ in step S110 recognizes that "the node device N ₂ itself has received the same data frame that was transmitted in step S102". In other words, the node device N ₂ at step S110 corresponds to the failed node as (D2) to transmit the data frame to the node γ in Figure 5 beta. Therefore, the node device N ₂ updates the weighting table 104-h ₂ -N ₂ in the same manner as in FIG. 5 (specifically, the weight associated with the node device N ₃ that is the LD of the transmission in step S102) To the maximum value).

Then, the node device N ₂ at step S111, as the LD for transferring a data frame, still select another adjacent node device N ₆ not try to send the data frame to the node device N _6.

The node device N ₆ are in the other node device N ₂ is LS of the transmitted data frame step S111, only the node device N _7, which is also GD is adjacent.
Therefore, the node device _{N 6} at step S112, select the node device _{N 7} as LD for transferring the received data frame at step S111, it transmits the data frame to the node device _{N 7.}

As described above, even if a failure occurs in the network 1, each node device behaves in an autonomous distributed manner, so that the data frame successfully reaches the GD.
In addition, even when a locally inappropriate node device is selected as the LD in the data frame transfer, the route from the GS to the GD is finally selected as the entire network. This is because each node device sequentially selects node devices that can be selected as LDs, and performs backtracking operations when there are no more node devices that can be selected.

Specifically, in the example of FIG. 6, the node device N ₂ selects the node device N ₃ as LD in step S102, it turns out to result unsuitable for in step S110. However, the operation of steps S103 to S110 succeeds in selecting the route <N ₁ , N ₂ , N ₆ , N ₇ > from the GS to the GD finally as the entire network 1.

The route selected in this way is learned and contributes to the efficiency of data frame transfer from the next time. The efficiency of learning will be described in detail as follows.
As a result of receiving the data frame in step S110, the node device N ₂ learns the weighting table 104-h ₂ -N ₂ and sets the weight associated with the node device N ₃ to the maximum value. Therefore, when the node device N ₂ receives from the adjacent node device N ₁ a new data frame having the node device N ₇ as GD, the node device N ₆ selects the node device N ₆ as an LD from the beginning. That is, as a result of autonomous distributed learning, the entire network 1 efficiently transmits data frames to the GD through the path <N ₁ , N ₂ , N ₆ , N ₇ > without trial and error including backtracking. It becomes possible.

Furthermore, according to the first embodiment, the influence of inappropriate LD selection or the influence of a local failure does not reach the entire network 1 and is locally limited. That is, according to the first embodiment, for example, even if a failure occurs in the link between the node devices N ₄ and N ₇ , the control frame for inquiring about an alternative route is flooded to all the node devices in the entire network 1. Don't do it. Therefore, according to the first embodiment, even if a failure or a loop occurs locally, a situation in which a broadcast storm is caused in the entire network 1 does not occur.

In the example of FIG. 6, the node device N ₁ does not recognize any failure in the link between the node devices N ₄ and N ₇ or the loop <N ₃ , N ₄ , N ₅ , N ₃ >. It is clear. This means that the influence of inappropriate LD selection or local failure is limited locally and does not reach the entire network 1.

The fact that the influence of the problem is locally limited means that the local problem is not positively fed back to the entire network 1 and does not diverge, and the network 1 is stable as a system. is there. Another example of the problem being limited locally is, for example:

For example, there is a link between the node devices N ₅ and N _{7 in} the network 1, and the node device N ₇ is associated with a lighter weight than the node device N ₃ in the weighting table 104-h ₅ -N ₅ . Suppose that Then, it transmits the data frame to the node device _{N 7} node device _{N 5} immediately after step S105 selects the node device _{N 7} as LD. As a result, the transmission of steps S108 to S112 is not performed, and not only the node device N ₁ but also the node devices N ₂ and N ₃ recognize no occurrence of the failure. Thus, problems such as link failures and loops affect only a minimal local range depending on where the problem occurs.

Next, the configuration and operation of the node device 100 and the autonomous distributed cooperative operation realized in the entire network 1 will be described in more detail.
The data frame according to the first embodiment includes header information including LD, LS, GD, GS, FID, type, and length fields, and a payload, as in the data frame 302 illustrated in FIG. For example, the data frame 301 in FIG. 5 has the same format as the data frame 302.

Although not particularly limited, a part of the header information may be stored in the ad hoc header, and the remaining part of the header information may be stored in the data header. In this case, for example, LD (local destination address), LS (local source address), type (frame type), and length (frame size) are stored in the ad hoc header. GD, GS, and FID are stored in the data header.

In the LD field, LS field, GD field, and GS field of the data frame 302, the node ID of each node device that is the LD, LS, GD, and GS of the data frame 302 is specified. In the FID field of the data frame 302, the FID generated by the node device that is the GS of the data frame 302 and assigned to the data frame 302 is specified.

In the type field of the data frame 302, a predetermined constant indicating the type “data frame” is designated. Also, the length of the payload is specified in the length field of the data frame 302. The payload of the data frame 302 is a PDU of a higher layer protocol than the protocol in which the data frame 302 is defined.

For example, assume that the MAC sublayer is virtually divided into two sublayers. The frame of the first embodiment may be defined in the lower sublayer of the two virtual sublayers, that is, other protocols defined in the MAC sublayer (such as Ethernet). A PDU may be included in the payload. In other words, the frame of the first embodiment may be a frame that encapsulates an Ethernet frame defined in the second layer. In this case, since the upper layer processing unit 111 is a processing unit that processes an Ethernet frame, it can also be realized by using a known MAC chip.

Hereinafter, for convenience of explanation, it is assumed that the payload of the data frame 302 is a MAC layer protocol frame (specifically, an Ethernet frame, for example).
However, of course, in some embodiments, the payload of the data frame 302 may be a PDU of a protocol defined at the network layer (third layer) or higher, or may be raw data that is not related to a specific communication protocol. May be. For example, the payload of the data frame 302 may be an IP (Internet Protocol) datagram. In this case, the upper layer processing unit 111 is a processing unit that processes the IP datagram.

The format of the data frame 302 is as described above, but more specific examples using specific values are as in the data frames 303 and 304.
The data frame 303 is a data frame transmitted from the node device N ₂ to the node device N ₃ in step S102 of FIG. Specific contents of the data frame 303 are as follows.

In the LD field, the node ID (that is, N ₃ ) of the node device N ₃ selected as the LD in the transmission in step S102 is designated.
In the LS field, the node ID (that is, N ₂ ) of the node device N ₂ that is the LS in the transmission in step S102 is designated.

In the GD field, the node ID (that is, N ₇ ) of the node device N ₇ specified by the node device N ₁ that is the GS at the time of transmission in step S101 is specified.
In the GS field, the node ID (that is, N ₁ ) of the node device N ₁ that is the GS is specified.

· FID The field node device _{N 1} is a GS (and less _{F a)} resulting FID is specified.
In the type field, a predetermined constant D indicating the type “data frame” is specified. For example, the type can be represented by 2 bits, and D = (00) ₂ may be used.

· The length field, the length P _a payload of the data frame 302 is designated. The length may be expressed in units of bytes, for example, or may be expressed in other units.
The payload includes a MAC layer protocol frame (for example, an Ethernet frame).

In addition, the data frame 304 in FIG. 7 is transmitted from the node device N ₃ that has received the data frame 303 to the node device N ₄ in step S103 in FIG. The specific contents of the data frame 304 are as follows.

In the LD field, the node ID (that is, N ₄ ) of the node device N ₄ selected as the LD in the transmission in step S103 is designated. In other words, when transfer node device _{N 3} rewrites the LD field.

In the LS field, the node ID (that is, N ₃ ) of the node device N ₃ that is the LS in the transmission in step S103 is specified. That is, when the transfer, the node device _{N 3} rewrites the LS field, sets the self node ID.

· GD, GS, FID, type, and each field length, the contents of the payload is the same as the data frame 303 is the node device _{N 3} received.
In addition, the hello frame in the first embodiment has a header including LD, LS, GD, GS, FID, and type fields as in the hello frame 311 in FIG. 7, but does not have a payload. Specific examples of the hello frame 311 is hello frame 312, the hello frame 312 is transmitted by the node device _{N 3} in step S1203 of FIG. 42 described later.

In the LD field of the hello frame 311, a special value indicating a broadcast to all node devices adjacent to the node device that transmits the hello frame 311 is designated. Note that “broadcast” here is “broadcast to all adjacent node devices”, not “flooding to the entire network 1”.

Hereinafter, for convenience of explanation, it is assumed that the node ID is represented by 3 bytes in the first embodiment, and “0x” represents a hexadecimal number. Also, it is assumed that 0x000000 and 0xFFFFFF are reserved and are not used as normal node IDs.

In all the hello frames in the first embodiment, similarly to the hello frame 312, 0xFFFFFF is specified in the LD field as a special value indicating broadcast to all node devices adjacent to the node device that transmits the hello frame. ing.

In the LS field of the hello frame 311, the node ID of the node device itself that transmits the hello frame 311 is specified. Therefore, N ₃ that is the node ID of the node device N ₃ is specified in the LS field of the hello frame 312 transmitted by the node device N ₃ .

Also, in all hello frames in the first embodiment, a special value 0x000000 representing null is designated in the GD field. This is because the hello frame is only used by the adjacent node device and is not transferred.

In the GS field of the hello frame 311, the node ID of the node device itself that transmits the hello frame 311 is specified as in the LS field. Accordingly, N ₃ that is the node ID of the node device N ₃ is specified in the GS field of the hello frame 312.

In the FID field of the hello frame 311, the FID generated by the node device that transmits the hello frame 311 and assigned to the hello frame 311 is specified. Similarly, in the FID field of the hello frame 312, the FID (hereinafter referred to as F _b ) generated by the node device N ₃ that transmits the hello frame 312 and assigned to the hello frame 312 is designated.

In the type field of the hello frame 311, a predetermined constant indicating the type “hello frame” is designated. Specifically, the type “hello frame” is represented by a predetermined constant H as exemplified in the hello frame 312, and may be H = (10) ₂ , for example.

In addition, the ACK frame in the first embodiment has a header including LD, LS, GD, GS, FID, and type fields as in the ACK frame 321 in FIG. 7, but does not have a payload. A specific example of the ACK frame 321 is the ACK frame 322. Also, ACK frame 322, when the node device _{N 2} has transmitted the data frame 303 to the node device _{N 3} in step S102 in FIG. 6, an ACK frame is the node device _{N 3} returns to the node device _{N 2.} In Figure 42 below, and the reply of the ACK frame 322 from the node device _{N 3} to the node device _{N 2,} expressed as the step S102a.

In the LD field of the ACK frame 321, the node ID of the adjacent node device that transmitted the data frame that triggered the transmission of the ACK frame 321 is specified. Therefore, for example, in the LD field of the ACK frame 322, N that is the node ID of the adjacent node device N ₂ of the node device N ₃ that transmitted the data frame 303 that triggered the transmission of the ACK frame 322 by the node device N _{3 2} is specified.

In the LS field of the ACK frame 321, the node ID of the node device itself that transmits the ACK frame 321 is specified. Therefore, N ₃ that is the node ID of the node device N ₃ is specified in the LS field of the ACK frame 322 transmitted by the node device N ₃ .

Also, since the ACK frame is not transferred as in the case of the hello frame, the special value 0x000000 representing null is specified in the GD field in all the ACK frames in the first embodiment.

In the GS field and FID field of the ACK frame 321, the values of the GS field and FID field of the data frame that triggered the transmission of the ACK frame 321 are copied. As described above, the data frame is uniquely identified in the network by the combination of the values of the GS field and the FID field. Therefore, the node device that transmits the ACK frame 321 can identify which data frame the ACK frame 321 is for in the node device that has received the ACK frame 321 by copying the value from the received data frame. It becomes possible.

Therefore, the ACK frame 322 for example, transmits the received data frame 303 as a trigger, the value of GS field and the FID field, as well as the data frame 303, respectively _{N 1} and _{F a.}

In the type field of the ACK frame 321, a predetermined constant indicating the type “ACK frame” is designated. Specifically, the type “ACK frame” is represented by a predetermined constant A as exemplified in the ACK frame 322, and may be, for example, A = (11) ₂ .

Note that the format of the frame shown in FIG. 7 is merely an example, and the arrangement order of the fields included in the frame can be appropriately determined according to the embodiment, and the frame includes other fields not shown. May be. The frame may further include a trailer such as FCS (Frame Check Sequence).
In the following, for simplification of description, when there is no possibility of confusion, for example, “LD field” may be simply referred to as “LD”. The same applies to the other fields.

FIG. 8 is a diagram showing an example of data stored in the buffer unit 109 shown in FIG. The buffer unit 109 includes a plurality of entries respectively corresponding to individual data frames received by the receiving unit 101. Each entry includes a timeout time and the received data frame.

Figure 8 illustrates the entries that the buffer unit _{109-N 3} of the node device _{N 3.} Specifically, when the node device N ₃ receives the data frame 303 of FIG. 7 from the node device N ₂ in step S102 of FIG. 6, the buffer unit 109-N ₃ stores the timeout time TI _{3, j} and the data frame. Entry 303 is created. Details of creation of entries in the buffer unit 109 will be described later with reference to FIG. The meaning of the timeout time TI _3, j is as follows.

Node device _{N 3} is the header of the data frame 303 received in step S102, is rewritten in step S103 as a data frame 304 of FIG. The node device _{N 3} transmits a data frame 304 at step S103.

The timeout time TI _{3, j in} FIG. 8 indicates how long the node apparatus N ₃ waits for reception of an ACK frame for the data frame 304 after transmitting the data frame 304. That is, if the node device N ₃ cannot receive an ACK frame for the data frame 304 from the node device N ₄ before the timeout time TI _{3, j} , the node device N ₃ times out and the data frame 304 to the node device N ₄ Judge that transmission failed.

In detail, as shown in FIGS. 32, 38, and 40, the timeout time set in the buffer unit 109 may be overwritten.
For example, the node device N ₄ that has failed to transmit the data frame to the node device N _{7 in} step S104 of FIG. 6 is stored in the buffer 109-N ₄ corresponding to the data frame received from the node device N ₃ in step S105. Update the timeout time. Timeout timing of the updated, specifically, indicating whether the reception of the ACK frame to data frame sent to the node device N ₅ in step S105 forever node device N ₄ waits.

FIG. 9 is a diagram illustrating an example of the adjacent node management table 103 in FIG. The adjacent node management table 103 has a node ID field and a last update time field.
For example, in the network 1 of FIG. 1, node devices N ₁ , N ₃ , and N ₆ are adjacent to the node device N ₂ . Therefore, the node adjacent node management table _{103-N 2} of the apparatus _{N 2,} these three adjacent node device _N 1, _{N 3,} and _{N 6} has three entries respectively corresponding to. In each entry corresponding to the adjacent node device _N i (i = 1, 3, 6), are stored _{N i} is the node ID of the adjacent node device _{N i} is the node ID field, last update time field Stores the time TA _{2, i} when the entry was last updated.

In the network 1 of FIG. 1, node devices N ₂ , N ₄ , and N ₅ are adjacent to the node device N ₃ . Therefore, the adjacent node management table _{103-N 3} of the node device _{N 3,} there are three entries respectively corresponding to the three adjacent node device _N 2, _{N 4,} and _{N 5.} In each entry corresponding to the adjacent node device _N i (i = 2, 4, 5), are stored _{N i} is the node ID of the adjacent node device _{N i} is the node ID field, last update time field Stores the time TA _{3, i} when the entry was last updated.

FIG. 10 is a diagram illustrating an example of the weighting table 104 in FIG. FIG. 10 shows a weighting table 104-N ₃ of the node device N ₃ of FIG. 1 as a specific example.
As shown in FIG. 3, “weighting table 104” is a general term for a plurality of weighting tables 104-1 to 104-M managed for each GD. Each weighting table 104-i (1 ≦ i ≦ M) stores a corresponding GD.

Each weighting table 104-i (1 ≦ i ≦ M) has one or more entries, and each entry has a last update time field, an LD field, and a weight field. The last update time field stores the time when the entry was last updated for weight learning, the LD field stores the node ID of the adjacent node device, and the weight field associates with the adjacent node device. Stored weight values.

In the example of FIG. 10, since the first weighting table 104-1-N ₃ is a table for transmitting a data frame in which the node device N ₇ is designated as GD, the node ID of the node device N _{7 is} GD. stores certain _{N 7.}

In the network 1 of FIG. 1, node devices N ₂ , N ₄ , and N ₅ are adjacent to the node device N ₃ . Therefore, the weighting table 104-1 -N ₃ has three entries respectively corresponding to these three adjacent node devices N ₂ , N ₄ and N ₅ . The contents of each entry corresponding to the adjacent node device N _i (i = 2, 4, 5) in the weighting table 104-1-N ₃ are as follows.

In the last update time field, the last update time TW _{3, 7, i} of the entry is stored.
In the LD field, N _i that is the node ID of the adjacent node device N _i is stored.

· Weight the field, the weight _{W 3, 7} associated with the adjacent node device _{N i, i} is stored.
That is, the weights W _{3, 7, and i} are referred to when the node device N ₃ transmits a data frame designating the node device N ₇ (that is, GD corresponding to the weighting table 104-1-N ₃ ) as GD. is a weight corresponding to the adjacent node device N _i.

Similarly, in the example of FIG. 10, the second sheet of the weighting table 104-2-N3, since the node device _{N 4} is a table for transmission of the data frame designated as GD, node of the node device _{N 4} as GD N ₄ which is an ID is stored.

In the network 1 of FIG. 1, since the node devices N ₂ , N ₄ , and N ₅ are adjacent to the node device N ₃ , the weighting table 104-2 -N ₃ also includes these three adjacent node devices N _It has three entries, each corresponding to ₂ , N ₄ , and N ₅ . The contents of each entry corresponding to the adjacent node device N _i (i = 2, 4, 5) in the weighting table 104-1-N ₃ are as follows.

In the last update time field, the last update time TW _{3, 4, i} of the entry is stored.
In the LD field, N _i that is the node ID of the adjacent node device N _i is stored.

· Weight the field, the weight _{W 3, 4} associated with the neighboring node device _{N i, i} is stored.
Of course, the weighting table 104-N ₃ may include a weighting table 104-jN ₃ (j> 2) associated with another GD.

Note the following points. That is, if the weighting table 104 is the same GD, even if a data frame having a different combination of FID and GS is transmitted, the weight of the LD serving as the transmission destination is updated each time transmission is performed. For example, when a certain data frame is transmitted, even if the weight of a specific LD is increased due to a link failure (even if the priority is low), the link is immediately transmitted with another data frame (GD and LD are the same). If the failure is resolved and transmission is successful, the weight of the LD becomes small (priority becomes high). On the other hand, if a plurality of different data frames (GD and LD are the same) continue to fail and transmission fails due to a link failure, data frames with the same FID and GS combination have only been tried once. However, the weight of the corresponding LD may become the maximum value.

FIG. 11 is a diagram for explaining changes in the weighting table 104-1-N ₃ in FIG. In the example of FIG. 11, T _a <T _b <T _c <T _d <T _e .
For example, in the time of receiving the data frame from the node device _{N 2} at step S102 of FIG. 6, the weighting table _{104-N 3} of the node device _{N 3} is the weighting table _{104-1-N 3} corresponding to the node device _{N 7} Is not present. Then, it is assumed that a new weighting table 104-1-N ₃ having the following contents is created in the weighting table 104-N ₃ with the reception of step S102.

• Three of the last update time of entry is both time T _a.
In all three entries, the weights W _{3, 7, and i} associated with the adjacent node devices N _i (i = 2, 4, 5) are all 0.5.

For simplification of description with respect to FIG. 6, among the two adjacent node devices N ₄ and N ₅ , the node device N ₄ has a lighter weight in the weighting table 104 -h ₃ -N ₃ . “Associated with each other”. That is, FIGS. 10 and 11 are examples of h ₃ = 1, and in the description of FIG. 6, it is assumed that W _3,7,4 <W _3,7,5 .

However, for example, as shown in FIG. 11, there may be a case where W _3,7,2 = W _3,7,4 = W _3,7,5 = 0.5. In the example of FIG. 11, since the node devices N ₄ and N ₅ are associated with the same weight 0.5, the node device N ₃ uses any of the node devices N ₄ and N ₅ as the transmission LD in step S103. may be selected, but if, as in the example of FIG. 6, and chose the node device N ₄ as LD.

Then, the node device _{N 3} in step S103 transmits the data frame to the node apparatus _{N 4.} Thereafter, when the node device N ₄ transmits an ACK frame to the node device N ₃ as shown in step S103a in FIG. 42, the node device N ₃ recognizes that the transmission of the data frame to the node device N ₄ is successful.

Then, as in the example of FIG. 5, the node device _{N 3} decreases the value of the weight _{W 3,7,4} associated with the node apparatus _{N 4.} In the example of FIG. 11, specifically, the node device N _{3 updates} the values of W _{3, 7} , and 4 from 0.5 to 0.4. Also, the node device N ₃ is the last update time field of the entry corresponding to the node device N _4, it sets the current time T _b.

Thereafter, as shown in FIG. 6, the node device N ₃ receives the same data frame again in step S106. As a result, as described with reference to FIG. 6, the node device N _{3 sets} the values of the weights W ₃ , _7, and ₄ associated with the node device N ₄ in the weighting table 104-1-N ₃ to 0.4. To the maximum value of 1.0. Also, the node device N ₃ is the last update time field of the entry corresponding to the node device N _4, it sets the current time T _c.

Subsequently, as shown in step S107 of FIG. 6, the node device N ₃ selects the node device N ₅ as an LD and transmits a data frame. Thereafter, when the node device N ₅ transmits an ACK frame to the node device N ₃ as shown in step S107a in FIG. 42, the node device N ₃ recognizes that the transmission of the data frame to the node device N ₅ is successful.

Then, as in the example of FIG. 5, the node device _{N 3} decreases the value of the weight _{W 3,7,5} associated with the node device _{N 5.} In the example of FIG. 11, specifically, the node device N _{3 updates} the values of W _{3, 7} , and 5 from 0.5 to 0.4. Also, the node device N ₃ is the last update time field of the entry corresponding to the node device N _5, sets the current time T _d.

Thereafter, as shown in FIG. 6, the node device N ₃ receives the same data frame again in step S109. As a result, as described with respect to FIG. 6, the value of the weight _{W 3,7,5} which is associated with the node device _{N 5} in the weighting table _{104-1-N 3,} the maximum value from 0.4 1 Update to .0. Also, the node device N ₃ is the last update time field of the entry corresponding to the node device N _5, sets the current time T _e.

As described above, the weighting table 104-1 -N ₃ is updated when an ACK frame is received or when a data frame that is the same as a transmitted data frame is received.

12 and 13 are diagrams showing examples of the FID management table 105 in FIG. As shown in FIGS. 12 and 13, the FID management table 105 includes fields for FID, GS, LD, OLS, and last update time.

The FID field and GS field in the FID management table 105 are fields for uniquely identifying the data frame, and values are copied from the FID field and the GS field of the received data frame, respectively.

In the LD field of the FID management table 105, the node ID of the adjacent node device last selected as the LD is stored in order to transmit the data frame identified by the values of the FID field and the GS field.

In the OLS field of the FID management table 105, the node ID of the adjacent node device designated in the LS field of the data frame when the data frame identified by the values of the FID field and the GS field is first received. Stored. The OLS field is also used to remove the OLS from the LD candidates when selecting the LD for data frame transfer, and is also used to determine the LD during the backtrack operation.

In the last update time field of the FID management table 105, the time when the entry was last updated is stored.
FIGS. 12 and 13 show the FID management table 105 of each node device in steps S101 to S112 in FIG. 6 as a specific example. Hereinafter, the times at which steps S101 to S112 are executed are represented as TF ₁₀₁ to TF ₁₁₂ , respectively.

When the node device N ₁ transmits a data frame to the node device N ₂ in step S101, the node device N ₁ creates a new entry E ₁ in the FID management table 105-N ₁ . Then, the node device N ₁ sets the FID and GS values of the transmitted data frame in the FID field and GS field of the entry E ₁ .

Here, the GS and FID values of the data frame are not rewritten even if the data frame is transferred through the network 1 as described above. Therefore, the FID and GS values of the data frames transmitted in steps S101 to S112 in the network 1 in FIG. 6 are F _a and N ₁ , respectively, as in the data frames 303 and 304 in FIG. Therefore, the node device _{N 1} in step S101, the FID field and GS field of the entry _{E 1,} sets the value of _{F a} and _{N 1,} respectively.

The value of each step S102 ~ S112 follows another node device sets the FID field and GS field of the entry of each FID management table 105, which is also a _{F a} and _{N 1.} Therefore, the description regarding the FID field and the GS field is omitted below. Also, the node device _{N 1} in step S101, the _{N 2} is a node ID of the node device _{N 2} selected as LD, it sets the LD field of the entry _{E 1.}

By the way, regarding a specific data frame uniquely identified by a pair of GS and FID values, the OLS is designated as the LS of the specific data frame when the specific data frame is first received. An adjacent node device identified by a node ID.

However, in this way defining the OLS, for example, when the node device N ₁ transmits a data frame becomes GS, for the node device N ₁ itself, OLS becomes undefined for transmission data frames. Therefore, the definition of OLS is expanded below. Specifically, it defined as "node when the device N _i itself transmits the data frame become GS includes a OLS for the node device N _i itself about the data frame is the node device N _i itself" To do.

In other words, the OLS, within the scope of a network node apparatus N _i itself is aware directly, a node device which is recognized as the origin of the data frame to the node device N _i. Note Here, the "range of a network node apparatus N _i itself is aware directly" ranges of 1 or less hops as viewed from the node device N _i, the node device N _i itself specifically, only the adjacent node device of the node device N _i contains. For example, in the example of FIG. 2, only the range of the network that is directly recognized by the node device N ₁₀₅ itself is indicated by a solid line.

From the definition of the above extended OLS, value node device _{N 1} is set to the OLS field of the entry _{E 1} in step S101, the node device _{N 1} its own node ID (i.e. _{N 1).} If the node device N ₁ receives a data frame having _a GS value of N ₁ and an FID value of Fa in the future, the node device N ₁ will be notified based on the entry E ₁ created as described above. N ₁ has received a data frame transmitted by itself.

Also, the node device _{N 1} in step S101 sets the current time _{TF 101} in the last update time field of the entry _{E 1.} In the following steps S102 to S112, the values set by the other node devices in the last update time fields of the entries in the FID management table 105 are the same as the times TF ₁₀₂ to S112 when the steps S102 to S112 are executed. TF ₁₁₂ . Therefore, the description regarding the last update time field is also omitted below.

Then, the node device N ₂ receiving the data frame from the node device N ₁ in step S101 adds a new entry E ₂ to the FID management table 105-N ₂ when transmitting the data frame to the node device N ₃ in step S102. create. Then, in the entry E ₂ , the node device N ₂ sets N ₁ in the OLS field and N ₃ in the LD field.

Subsequently, the node device N _{3 that} has received the data frame from the node device N ₂ in step S102 transmits a new entry E ₃ in the FID management table 105-N ₃ when transmitting the data frame to the node device N ₄ in step S103. Create Then, in the entry E ₃ , the node device N ₃ sets N ₂ in the OLS field and N ₄ in the LD field.

Subsequently, the node device N ₄ receiving the data frame from the node device N ₃ in step S103 transmits a new entry E ₄ in the FID management table 105-N ₄ when transmitting the data frame to the node device N ₇ in step S104. Create Then, the node device _{N 4} entries _{E 4,} the OLS field is set to _{N 3,} the LD field is set to _{N 7.}

However, transmission in step S104, the fail due to failure of a link between the node device N ₄ and N _7. That is, the node apparatus _{N 4,} it is not possible to receive the ACK frame from the node device _{N 7,} times out. As a result, the node device N _4, as in step S105, and reselects another adjacent node device N ₅ as the next LD, transmits the data frame to the node device N _5.

Here, the data frames transmitted at steps S104 and S105, the value of the value of FID is _{F a} GS is _{N 1,} the same data frame. Accordingly, the node apparatus N ₄ in step S105, instead of creating a new entry, and updates the existing entry E _4.

Specifically, the node apparatus _{N 4} in step S105, the entry _{E 4,} overwrites the value of the LD field _{N 5.} Incidentally, no matter the value is transmitted value F _a same data frame node device N ₄ is the FID is many times N ₁ of GS, the "node apparatus N ₄ has received the data frame to the first node apparatus The fact that “from N ₃ ” does not change. Therefore, the value of the OLS field of the entry E ₄ is not rewritten and remains N ₃ .

Subsequently, the node device N _{5 that} has received the data frame from the node device N ₄ in step S105 transmits a new entry E ₅ in the FID management table 105-N ₅ when transmitting the data frame to the node device N ₃ in step S106. Create The node device N ₅ sets N ₄ in the OLS field and N ₃ in the LD field in the entry E ₅ .

Then, the node device N _{3 that} has received the data frame from the node device N ₅ in step S106 searches the FID management table 105-N ₃ using the GS and FID values of the received data frame as keys, and sets the entry E ₃ locate. Since the entry E ₃ is found, the node device N ₃ can recognize that “the same data frame that the node device N ₃ itself once transmitted in step S103 was received in step S106”.

Therefore, the node device N ₃ updates the existing entry E ₃ instead of creating a new entry in the FID management table 105-N ₃ when transmitting the data frame to the node device N ₅ in the next step S107. To do. Specifically, the node device _{N 3} in step S107, in the entry _{E 3,} overwrites the value of the LD field _{N 5.} The value of the OLS field of the entry _{E 3} is never rewritten, it remains _{N 2.}

Then, the node device N _{5 that} has received the data frame from the node device N ₃ in step S107 searches the FID management table 105-N ₅ using the GS and FID values of the received data frame as keys, and sets the entry E ₅ locate. Since the entry E ₅ is found, the node device N ₅ can recognize that “the same data frame that the node device N ₅ itself once transmitted in step S106 has been received in step S107”.

Therefore, the node device N ₅ updates the existing entry E ₅ instead of creating a new entry in the FID management table 105-N ₅ when transmitting the data frame to the node device N ₄ in the next step S108. To do. Specifically, the node device _{N 5} in step S108, in the entry _{E 5,} overwrites the value of the LD field _{N 4.} The value of the OLS field of the entry _{E 5} is never rewritten, it remains _{N 4.}

Then, the node device N _{4 that} has received the data frame from the node device N ₅ in step S108 searches the FID management table 105-N ₄ using the GS and FID values of the received data frame as keys, and sets the entry E ₄ locate. Since the entry E ₄ is found, the node device N ₄ can recognize that “the same data frame that the node device N ₄ itself once transmitted in step S105 has been received in step S108”.

Therefore, the node device N ₄ updates the existing entry E ₄ instead of creating a new entry in the FID management table 105-N ₄ when transmitting the data frame to the node device N ₃ in the next step S109. To do. Specifically, the node apparatus _{N 4} in step S109, in the entry _{E 4,} overwrites the value of the LD field _{N 3.} Note that the value of the OLS field of the entry E ₄ is not rewritten and remains N ₃ .

Then, the node device N _{3 that} has received the data frame from the node device N ₄ in step S109 searches the FID management table 105-N ₃ using the GS and FID values of the received data frame as keys, and sets the entry E ₃ locate. Since the entry E ₃ is found, the node device N ₃ can recognize that “the same data frame that the node device N ₃ itself once transmitted in step S103 was received in step S109”.

Therefore, the node device N ₃ updates the existing entry E ₃ instead of creating a new entry in the FID management table 105-N ₃ when transmitting the data frame to the node device N ₂ in the next step S110. To do. Specifically, the node device _{N 3} in step S110, the entry _{E 3,} overwrites the value of the LD field _{N 2.} The value of the OLS field of the entry _{E 3} is never rewritten, it remains _{N 2.}

Then, the node device N _{2 that} has received the data frame from the node device N ₃ in step S110 searches the FID management table 105-N ₂ using the GS and FID values of the received data frame as keys, and enters the entry E ₂ . locate. Since the entry E ₂ is found, the node device N ₂ can recognize that “the same data frame that the node device N ₂ itself once transmitted in step S102 has been received in step S110”.

Therefore, the node device N ₂ updates the existing entry E ₂ instead of creating a new entry in the FID management table 105-N ₂ when transmitting the data frame to the node device N ₆ in the next step S111. To do. Specifically, the node device _{N 2} at step S111, in the entry _{E 2,} overwrites the value of the LD field _{N 6.} Note that the value of the OLS field of the entry E ₂ is not rewritten and remains N ₁ .

The node device N _{6 that} has received the data frame from the node device N ₂ in step S111 adds a new entry E ₆ to the FID management table 105-N ₆ when transmitting the data frame to the node device N ₇ in step S112. create. The node device N ₆ sets N ₂ in the OLS field and N ₇ in the LD field in the entry E ₆ .

<About backtracking>
As described above, in the frame transmission method of the embodiment, when the node device determines that “transfer is impossible” when transferring the received data frame toward the final destination, the node device transmits the received data frame. Disguise yourself. That is, the node device performs backtracking.

For example, in the example shown in FIG. 14, the node device X first transmits a data frame in which the node device Y is designated as a GD (final destination) to the node device a. Here, it is assumed that the link between the node device b and the node device Y is disconnected. Then, as described with reference to FIG. 6, the data frame transmitted from the node device a to the node device b returns to the node device a via the node device c. As a result, the node device a detects that transmission to the node device b has failed. Subsequently, the node device transmits the data frame to the node device c. However, this data frame returns to the node device a via the node device b. Thereby, the node device a detects that the transmission to the node device b has also failed. Therefore, the node device a determines that “a data frame having the node device Y as GD cannot be transferred” and performs backtracking. That is, the node device a transmits the data frame first received from the node device X to the node device X that is the OLS (original transmission source adjacent node) of the data frame.

Thereafter, the node device X transmits the data frame received from the node device a to another adjacent node (here, the node d). As a result, the data frame arrives at the node device Y that is the final destination.

FIG. 15 is a diagram showing a sequence when backtracking occurs between the node devices X and a shown in FIG. That is, the node device X first transmits a data frame to the node device a. At this time, the node device X holds the data frame transmitted to the node device a in the buffer unit 109 shown in FIG.

The node device a receives the data frame transmitted from the node device X at time TE. Then, the node device a creates a new entry in the FID management table 105 and records information related to the received data frame.

FIG. 16 is an example of the FID management table 105. Although the FID management table 105 has been described with reference to FIGS. 12 to 13, more specifically, not only the LD, OLS, and last update time but also the ACK reception flag for the FID and GS pair, It manages the number of empty data transmissions, normal data transmissions, and entry time. The entry time represents the time when the node device first receives the data frame from the adjacent node, or the time when the node device transfers the data frame received from the adjacent node device to another adjacent node device. In the former case, the entry time may be a reception start time or a reception end time. In the latter case, the entry time may be a transfer start time or a transfer end time. In the following description, although not particularly limited, the entry time represents the time when the data frame is first received from the adjacent node device. The ACK reception flag, the number of empty data transmissions, and the number of normal data transmissions will be described later.

When the node device a receives the data frame transmitted from the node device X at time TE, the node device a creates a new entry as shown in FIG. In this example, a unique value F _X generated by the node device X that is a GS is recorded in the FID field. “Node X” is recorded in the GS field. In this example, since the data frame is transmitted to the node apparatus b, “node b” is recorded in the LD field. “Node X” is recorded in the OLS field. Then, the time at which the data frame transmitted from the node device X is received is recorded as the entry time TE and the last update time TF.

The node device a transfers the data frame transmitted from the node device X to the node device b and returns an ACK frame to the node device X. The node apparatus X recognizes that the transmitted data frame has arrived at the node apparatus a by receiving the ACK frame from the node apparatus a. However, even if the node device X receives the ACK frame, the node device X does not discard the data frame stored in the buffer unit 109, and until the predetermined holding period G elapses from the transmission time to the node device a. Holds the data frame.

On the other hand, the data frame transmitted from the node device a to the node device b returns to the node device a as shown in FIG. Then, the node device a performs backtracking to notify the node device X that “a data frame having the node device Y as GD cannot be transferred”. At this time, the node device a transmits the data frame to the node device X as described with reference to FIG. Then, since the node device X detects the data frame that it first transmitted to the node device a, it determines that “the node device a cannot transfer the data frame in which the node device Y is GD”. As a result, the node device X transmits the data frame to another adjacent node (node d in this example).

However, the buffer unit 109 of the node device X holds the data frame from when the data frame is transmitted to the node device a until the holding period G elapses. That is, before the time Tg, the data frame previously transmitted from the node device X to the node device a is held in the buffer unit 109 of the node device X. Therefore, if the backtracking operation by the node device a is executed before the time Tg, the node device a does not need to transmit the entire data frame to the node device X. It is only necessary to notify the node device X that “transfer cannot be performed”. In this case, the node device X can take out the data frame held in the buffer unit 109 and transmit it to the node device d in response to the notification from the node device a.

In order to realize the above operation, the node device a calculates the elapsed time from the entry time TE representing the time at which the data frame is received from the node device X to the current time T when executing the backtrack operation. That is, the elapsed time “T-TE” is calculated. If the elapsed time “T-TE” is shorter than the holding period G, the node device a determines that the data frame corresponding to the backtrack is held in the buffer unit 109 of the node device X. In this case, instead of transmitting the entire data frame, the node device a transmits a frame (hereinafter referred to as an empty data frame) for notifying frame identification information for identifying the data frame to the node device X. In this embodiment, the retention period G is the same for each node device.

FIG. 17 is a diagram showing a frame format used for backtracking. An example of the format of the data frame, hello frame, and ACK frame has been described with reference to FIG. However, the format of the frame transmitted and received by the node device according to the embodiment is not particularly limited as long as predetermined header information is set. Therefore, in the following, for example, it is assumed that the data frame has the format shown in FIG.

That is, the data frame has an ad hoc header and a payload. In the ad hoc header, LD (local destination address), LS (local source address), frame type (type), and frame size (length) are set. Each of these information elements is as described above. In the payload area, a data header and “data” are stored. In the data header, GS, GD, and FID are set. In this embodiment, only GS, GD, and FID are stored in the data header, but other information may be stored in addition to GS, GD, and FID. “Data” stored in the payload area is data to be transmitted to the GD.

In the payload of the hello frame and ACK frame, the data header is stored, but “data” is not stored. The hello frame, data frame, and ACK frame are identified by the frame type. Although not particularly limited, in this embodiment, for example, “0x0001”, “0x0002”, and “0x0003” are assigned to the frame types of the hello frame, the data frame, and the ACK frame, respectively.

FIG. 17B shows a format of an empty data frame transmitted in the backtrack operation. In the ad hoc header of the empty data frame, LD, LS, frame type, and frame size are set as in the normal data frame shown in FIG. For example, in the example illustrated in FIG. 14, “LD = X” and “LS = a” are set in the case of an empty data frame created during backtracking from the node device a to the node device X. In this example, “0x0004” is assigned to the frame type of the empty data frame. Further, the data size of the payload is set as the frame size.

* Only the data header is stored in the payload of the empty data frame, and the data to be transmitted to the final destination is not stored. As described above, GS, GD, and FID are set in the data header. The data header is basically not changed in the process of being transferred by each node device, and information generated in the GS is set as it is. Therefore, for example, in the example shown in FIG. 14, in the case of an empty data frame created during backtracking from the node device a to the node device X, “GS = X” and “GD = Y” are set, and the FID is a node The value generated by the device X is set as it is.

If the elapsed time “T-TE” is shorter than the holding period G, the node device a transmits an empty data frame to the node device X that is the OLS in the backtrack operation. In this case, the node device X refers to the ad hoc header and data header of the empty data frame and extracts the corresponding data frame from the buffer unit 109. Then, the node device X transmits the data frame extracted from the buffer unit 109 to another adjacent node (adjacent node d in this example).

Each node device can autonomously execute the above-described backtrack operation. For example, in the example illustrated in FIG. 14, the node device c can transmit an empty data frame in a backtrack operation for the node device b. Similarly, the node device b can transmit an empty data frame in the backtrack operation for the node device a.

As described above, the node device according to the embodiment transmits the entire data frame when the backtrack operation is performed before the elapsed time from when the data frame is first received (entry time) exceeds the holding period G. Instead, only the frame identification information for identifying the data frame is transmitted. Therefore, the size of the frame transferred during backtracking is reduced, and the frame transfer efficiency is improved.

By the way, when transmitting large data, the data is divided into a plurality of data units and continuously transmitted using a plurality of data frames. In this case, in the network according to the embodiment, there is a high possibility that the plurality of continuous data frames described above are transmitted through the same route. Then, in the example illustrated in FIG. 14, the node device a determines that “transfer to GD is impossible” for each of the plurality of continuous data frames described above. As a result, the node device a needs to perform a plurality of backtrack operations.

Therefore, when a plurality of empty data frames have the same destination adjacent node, the node device according to the embodiment aggregates these empty data frames and transmits them in one frame. In the example shown in FIG. 18, four data frames are transmitted through the same route, and all return to the node device a. Here, for the node apparatus a, the OLS of the four data frames is the node apparatus X. That is, the node device a has four empty data frames to be transmitted to the node device X. In this case, the node device a transmits one frame generated by aggregating these four empty data frames to the node device X. Hereinafter, a frame obtained by aggregating a plurality of empty data frames will be referred to as an “aggregated empty data frame”.

The format of the aggregated empty data frame is shown in FIG. In the ad hoc header of the aggregated empty data frame, LD, LS, frame type, and frame size are set as in the normal data frame shown in FIG. 17A or the empty data frame shown in FIG. Here, for LD and LS set in the ad hoc header of the aggregated empty data frame, values set in the ad hoc header of each aggregated empty data frame are used as they are. Accordingly, in the example illustrated in FIG. 18, “LD = X” and “LS = a” are set in the ad hoc header of the aggregated empty data frame transmitted from the node device a to the node device X. In this example, “0x0005” is assigned to the frame type of the aggregated empty data frame. The frame size of the aggregated empty data frame is determined according to the number of data headers stored in the payload.

In the payload of the aggregated empty data frame, “data headers” of a plurality of empty data frames transmitted to the same adjacent node are stored. In the example shown in FIG. 17C, n data headers are stored in the payload of one aggregated empty data frame.

When receiving the aggregated empty data frame, the node device X extracts a plurality of data headers from the payload. Then, the node device X extracts the data frame corresponding to each data header from the buffer unit 109 and transmits it to each other adjacent node (in this example, the adjacent node d).

Note that the aggregated empty data frame is created by aggregating a plurality of empty data frames in which the same LD is set. At this time, an aggregated empty data frame may be created from a plurality of empty data frames in which different GDs are set. In this case, the node device that has received the aggregated empty data frame may transmit a plurality of corresponding data frames to different adjacent nodes.

As described above, in the network according to the embodiment, a backtrack operation may be required to transmit the data frame to the final destination. At this time, the node device according to the embodiment transmits an empty data frame when it is expected that data to be transmitted during backtracking is held in the backtrack destination adjacent node. As a result, the data held in the backtrack destination adjacent node can be used effectively, and the amount of data related to the backtrack can be reduced. In addition, when a plurality of data headers are transmitted collectively using an aggregated empty data frame, the amount of data related to backtracking can be further reduced. Therefore, according to the frame transmission method of the embodiment, the frame transfer efficiency is improved.

Note that a communication method with a low bit rate is often adopted in order to extend the life of the battery installed in each node device. In this case, the frame size is generally reduced. Then, when transmitting large data, data is transmitted using a large number of data frames. Therefore, if the configuration of performing backtracking using the aggregated empty data frame according to the embodiment is adopted, the power consumption of each node device can be suppressed, and the life of the battery installed in each node device can be extended. it can.

For example, consider a case where 1500 bytes of data is transmitted in a network where the maximum frame size is 128 bytes. Here, for example, it is assumed that the ad hoc header is 20 bytes. In FIG. 17, the elements of the data header are only GS, DS, and FID, and the data length is 18 bytes. Here, it is assumed that the data length of the data header is 22 bytes. Then, the area where data can be stored for each frame is 86 bytes, and the 1500-byte data is transmitted using 18 data frames.

Here, it is assumed that the 18 data frames are continuously transmitted and backtracking occurs for all of them. Then, if the frame transmission method of the embodiment is not used, 18 backtrack frames are transmitted. On the other hand, if the aggregated empty data frame according to the frame transmission method of the embodiment is used, four data headers can be stored in the payload of each frame. Therefore, the number of aggregated empty data frames transmitted in backtrack according to the 18 data frames is 5. Thus, according to the method of the embodiment, the number of frames transmitted during backtracking is reduced, and the frame transfer efficiency is improved.

FIG. 19 is a flowchart showing the operation of the node device that performs backtracking. The processing of this flowchart is executed by the data frame processing unit 110 when it is determined that backtracking is necessary, for example. In the example illustrated in FIG. 14, when the data frame processing unit 110 of the node device a determines that the data frame received from the node device X cannot be transmitted to the final destination, the processing of the flowchart illustrated in FIG. 19 is started. In the following description, a data frame related to the backtracking operation may be referred to as a “target data frame”.

In step S1, the data frame processing unit 110 extracts the current time T. Each data device is assumed to have a clock. In this case, it is preferable that the clocks included in each node device are synchronized with each other.

In step S2, the data frame processing unit 110 extracts the aging time G of the buffer unit 109. Note that the aging time G of the buffer unit 109 is described as “holding time G” in the description with reference to FIGS. 14 to 18. In this example, the same value is used for the aging time G of the buffer unit 109 in each node device. In each node device, the aging time G is recorded in a predetermined memory area.

The aging time G of the buffer unit 109 is set to be sufficiently longer than the time from when a node device transmits a data frame until the data frame returns to the node device by the backtracking operation of the adjacent node device. The Therefore, the aging time G is set to about 30 seconds, for example, although it depends on the network configuration.

In step S3, the data frame processing unit 110 refers to the FID management table 105 with the FID and GS pair of the target data frame, and extracts the corresponding entry time TE. In the example illustrated in FIG. 14, when the node device a receives the target data frame from the node device X, the node device a creates an entry related to the target data frame in the FID management table 105. At this time, FID, GS, and the like are recorded in the target data frame. Then, when the target data frame is first transferred (that is, when it is transmitted to the node device b), the entry time TE is recorded. Therefore, the data frame processing unit 110 extracts the entry time TE recorded as described above.

In steps S4 to S5, the data frame processing unit 110 determines whether or not the target data frame is held in the destination node device of the backtrack operation. Here, the destination node device of the backtrack operation is the OLS of the target data frame, and is recorded in the FID management table 105. Hereinafter, the destination node device for the backtrack operation may be referred to as an “OLS node device”. In steps S 4 to S 5, specifically, if the elapsed time “T-TE” from the entry time TE to the current time T of the target data frame is shorter than the aging time G of the buffer unit 109, the target data frame Is determined to be held in the buffer unit 109.

At this time, if “G> T-TE” (step S5: Yes), the data frame processing unit 110 determines that the target data frame is held in the OLS node apparatus. In this case, the OLS node device can perform the transmission process using the target data frame held in the buffer unit 109 without newly receiving the target data frame. Therefore, in step S6, the data frame processing unit 110 creates an empty data frame for notifying frame identification information of the target data frame. As shown in FIG. 17B, the empty data frame has an ad hoc header and a payload. In the payload, only the data header of the target data frame is stored.

In the example shown in FIG. 14, “LD = X”, “LS = a”, “frame type = 0x0004”, and “frame size = data length of data header” are set in the ad hoc header of the empty data frame created by the node device a. Is done. In the data header stored in the payload, “GS = X”, “GD = Y”, and “FID = a value generated by the node device X” are recorded.

On the other hand, if “G> T-TE” is not satisfied (step S5: No), the data frame processing unit 110 determines that the target data frame is not held in the OLS node device. In this case, the OLS node apparatus must newly receive the target data frame in order to transmit data to the final destination. Therefore, the data frame processing unit 110 creates a normal data frame in step S7. In the normal data frame, data to be transmitted to the GS is stored in addition to the data header in the payload of the above-described empty data frame.

In step S8, the data frame processing unit 110 performs backtracking using the frame generated in step S6 or S7. That is, the data frame processing unit 110 stores the frame generated in step S6 or S7 in the transmission queue 114. Then, for example, the transmission unit 102 periodically reads and transmits a frame stored in the transmission queue 114. The transmission destination of the frame is the LD set in the ad hoc header.

FIG. 20 shows an example of the transmission queue 114. The transmission queue 114 stores a frame transmitted from the node device. That is, data frames (including empty data frames) generated by the data frame processing unit 110 are stored in the transmission queue 114. The transmission queue 114 may also store hello frames and ACK claims.

When a new frame is stored in the transmission queue 114, an entry number is assigned to each frame as shown in FIG. The transmission queue 114 stores LD, LS, frame type, ACK received flag, and payload for each entry number. Here, LD, LS, and frame type correspond to the ad hoc header of the transmission frame. Although not shown in FIG. 20A, the frame size may be stored in addition to the LD, LS, and frame type. The ACK received flag indicates whether or not a corresponding ACK frame has been received from the transmission destination node apparatus after the frame has been transmitted. Therefore, the ACK received flag of each entry is set to “not yet” when stored in the transmission queue 114.

In the payload area of the transmission queue 114, the payload data of each frame is stored. However, only the data header is stored in the payload of the empty data frame as shown in FIG. Therefore, when an empty data frame is stored in the transmission queue 114, only one data header is stored in the payload area.

For example, an entry 0x0001 shown in FIG. 20A stores an empty data frame transmitted from the node device a to the node device X in the backtrack operation in FIG. That is, “LD = X”, “LS = a”, and “frame type = 0x0004” obtained from the ad hoc header are stored. At this time, “not yet” is set in the ACK received flag. The data header of the empty data frame is stored in the payload area of this entry.

If the node device does not aggregate empty data frames shown in FIG. 18, the transmission unit 102 may immediately transmit the frame generated in step S6 or S7. In this case, the node device may not include the transmission queue 114. That is, the data frame processing unit 110 may pass the created frame to the transmission unit 102, and the transmission unit 102 may transmit the frame immediately.

FIG. 21 and FIG. 22 are flowcharts showing processing for collecting empty data frames in the backtrack operation. The processing of this flowchart is repeatedly executed by the data frame processing unit 110 at predetermined time intervals. Note that the node device includes a timer in which a constant value is set. This timer counts down by a clock signal or the like, generates an event when it reaches zero, and returns to the constant value again. Then, the data frame processing unit 110 starts the processing of the flowcharts shown in FIGS. 21 to 22 using the event generated by this timer as a trigger.

In step S11, the data frame processing unit 110 initializes variables related to the backtrack operation. For example, in the FID management table 105, the number of empty data transmissions and the number of normal data transmissions for each entry are initialized to “zero”. Also, the variable i for designating each entry in the transmission queue 114 in order is initialized to “1”.

In step S12, the data frame processing unit 110 locks the transmission queue 114. During the period when the transmission queue 114 is locked, the transmission unit 102 cannot read and transmit a frame from the transmission queue 114.

In steps S13 to S17, the data frame processing unit 110 accesses each entry in the transmission queue 114 and extracts an unprocessed empty data frame. That is, in steps S13 to S14, it is checked whether or not a frame is stored in the i-th entry. At this time, if a frame is stored in the i-th entry, the process of step S15 is executed. On the other hand, when the processes after step S15 are executed for all the frames stored in the transmission queue 114 (step S14: No), the process of step S31 is executed.

In steps S15 to S16, the data frame processing unit 110 checks the frame type and ACK received flag of the frame stored in the target entry. If an untransmitted non-aggregated empty data frame is stored in the target entry, the process proceeds to step S21. In this embodiment, the frame types of the hello frame, normal data frame, ACK frame, empty data frame (empty non-aggregated empty data frame), and aggregated empty data frame are 0x0001, 0x0002, 0x0003, 0x0004, and 0x0005, respectively. . Therefore, if “frame type = 0x0004” and “ACK received flag = not yet” are detected in the target entry, the process proceeds to step S21. For example, in the example shown in FIG. 20 (a), “Yes” is determined when steps S15 to S16 are executed for entry 0x0001, and “No” is determined when steps S15 to S16 are executed for entry 0x0002. .

Note that if the frame type of the target entry is not 0x0004, or if the ACK received flag is “completed”, the variable i is incremented in step S17. In this case, returning to step S13, the next entry in the transmission queue 114 is selected.

In steps S21 to S22, the data frame processing unit 110 confirms an empty data frame stored in the work area. Here, the work area is a buffer memory that temporarily stores empty data frames extracted from the transmission queue 114. The work area is used to aggregate a plurality of empty data frames. Then, the data frame processing unit 110 checks whether an empty data frame in which the same LD as the target entry is set exists in the work area.

When no empty data frame in which the same LD as the empty data frame of the target entry is set exists in the work area, the data frame processing unit 110 sets “completed” in the ACK received flag of the target entry in step S23. To do. Note that the frame of the entry for which the ACK received flag is set to “completed” has already been transmitted and the corresponding ACK in the flowcharts shown in FIGS. 21 to 22 even before actual transmission. Treated as if the frame was received. Therefore, the frame of the entry whose ACK received flag is set to “completed” is not selected in step S16 even if it is an empty data frame.

In step S24, the data frame processing unit 110 stores the empty data frame of the target entry in the work area. Thereafter, this empty data frame is in the aggregation processing state. In step S25, the data frame processing unit 110 increments the variable i and returns to step S13. That is, the next entry is selected.

When an empty data frame in which the same LD as the empty data frame of the target entry is set exists in the work area (step S22: Yes), step S26 is executed. In step S26, the data frame processing unit 110 adds the empty data frame of the target entry to the empty data frame in the work area detected in step S22. At this time, the ad hoc headers (LD, LS, frame type) of these two empty data frames are the same. Therefore, in step S26, the payload of the empty data frame of the target entry is added to the empty data frame in the work area. At this time, “completed” is set in the ACK received flag of the target entry.

In step S27, the data frame processing unit 110 checks whether the size of the empty data frame obtained in step S26 is equal to or smaller than a predetermined threshold value. This threshold value is used to determine whether or not the payload of another empty data frame can be added to the empty data frame in the aggregation processing state stored in the work area. Therefore, for example, this threshold is determined to be a value smaller by the data header length than the maximum frame size defined by the network according to the embodiment. If the size of the empty data frame is equal to or smaller than the threshold value, it is determined that a data header can be further added to the empty data frame in the aggregation processing state. In this case, after the variable i is incremented in step S25, the process returns to step S13. That is, the next entry is selected.

On the other hand, if the size of the empty data frame exceeds the threshold value, the data frame processing unit 110 sets a value representing the aggregated empty data frame to the frame type of the empty data frame in step S28. In this example, “0x0005” is set. That is, an aggregated empty data frame is generated. Then, the data frame processing unit 110 generates a new entry in the transmission queue 114 and stores the generated aggregated empty data frame in the entry. At this time, “not yet” is set in the ACK received flag of this entry. Thereafter, after the variable i is incremented in step S25, the process returns to step S13. That is, the next entry is selected.

When all entries in the transmission queue 114 are selected (step S14: No), the data frame processing unit 110 executes the process of step S31. Step S31 is executed for each empty data frame in the work area, but is basically the same as step S28. That is, in step S31, first, a value representing an aggregated empty data frame is set in the frame type of each empty data frame in the work area. As a result, an aggregated empty data frame is generated. Subsequently, each aggregated empty data frame is stored in the transmission queue 114. At this time, “not yet” is set in the corresponding ACK received flag.

In step S32, the data frame processing unit 110 unlocks the transmission queue 114. Therefore, thereafter, the transmission unit 102 can read and transmit a frame from the transmission queue 114.

Next, an embodiment of the aggregation process shown in FIGS. 21 to 22 will be described. In the following, it is assumed that the transmission queue 114 is in the state shown in FIG. It is assumed that the work area has been initialized.

(1) The entry 0x0001 of the transmission queue 114 is selected. In this entry, “frame type = 0x0004 (empty data frame)” and “ACK received flag = not yet” are set. Therefore, it is determined as “Yes” in Step S16, and the processing after Step S21 is executed.

(2) At this time, since no empty data frame is stored in the work area, it is determined as “No” in step S22. Therefore, “completed” is set in the ACK received flag of entry 0x0001 in step S23. In step S24, the empty data frame of entry 0x0001 is stored in the work area. It is assumed that “data header 1” is stored in the payload of this empty data frame.

(3) No empty data frame is stored in entries 0x0002 to 0x0009. In this case, since “No” is determined in step S16 for each entry, the processing from step S21 onward is not executed.

(4) Entry 0x0010 is selected. This entry is determined as “Yes” in step S16 as in the case of entry 0x0001. Therefore, the process after step S21 is performed.

(5) The LD of entry 0x0010 is “X”. In the work area, an empty data frame extracted from entry 0x0001 is stored. That is, the LD of the empty data frame stored in the work area is also “X”. Therefore, in step S26, the empty data frame extracted from the entry 0x0010 is added to the empty data frame stored in the work area. As a result, an aggregated empty data frame in which “data header 1 + data header 2” is stored in the payload is stored in the work area. Note that the LD of this aggregated empty data frame remains “X”. Furthermore, “completed” is set in the ACK received flag of entry 0x0010.

(6) Assume that the size of the aggregated empty data frame created in (5) above is smaller than the threshold value. Then, the next entry is selected. However, no empty data frame is stored in entry 0x0011. Therefore, the next entry is further selected without executing the processing after step S21.

(7) Entry 0x0012 is selected. This entry is determined as “Yes” in step S16 as in the case of entry 0x0001 or entry 0x0010. Therefore, the process after step S21 is performed.

(8) The LD of entry 0x0012 is “X”. The LD of the aggregated empty data frame stored in the work area is also “X”. Accordingly, in step S26, the empty data frame extracted from the entry 0x0012 is added to the aggregated empty data frame stored in the work area. As a result, an aggregated empty data frame in which “data header 1 + data header 2 + data header 3” is stored in the payload is stored in the work area. Note that the LD of this aggregated empty data frame also remains “X”. Furthermore, “completed” is set in the ACK received flag of entry 0x0012.

(9) Assume that the size of the aggregated empty data frame created in (8) above is smaller than the threshold value. Then, the next entry is searched. However, in this example, no unselected entry is left. Therefore, the process of step S31 is performed.

(10) A new entry 0x0013 is created in the transmission queue 114, and the aggregated empty data frame generated in (8) above is stored in this entry. At this time, “0x0005” is set as the frame type. In addition, “not yet” is set in the ACK received flag.

The transmission queue 114 is updated to the state shown in FIG. 20B by the above procedures (1) to (10). Thereafter, when the lock of the transmission queue 114 is released, the transmission unit 102 extracts and transmits a frame in which “not received” is set in the ACK received flag in the transmission queue 114. Therefore, the transmitting unit 102 transmits the aggregated empty data frame stored in the entry 0x0013. At this time, the aggregated empty data frame is transmitted to the adjacent node specified by the LD. That is, in the example illustrated in FIG. 20B, the aggregated empty data frame is transmitted to the node device X.

As described above, when a plurality of empty data frames in which the same LD is designated are stored in the transmission queue 114, the node device of the embodiment aggregates and transmits the plurality of empty data frames. Therefore, the number of backtrack operations is reduced and data transfer efficiency is improved.

FIG. 23 is a flowchart showing an empty data frame reception process. In the process of this flowchart, the node apparatus receives an empty data frame or an aggregated empty data frame from an adjacent node apparatus, and is determined to be an empty data frame or an aggregated empty data frame in step S801a of the data frame reception process of FIG. Is executed by the data frame processing unit 110. Here, the empty data frame and the aggregated empty data frame are identified by the value of the frame type set in the ad hoc header of the received frame. In the description of this flowchart, it is assumed that “empty data frames” include both empty data frames and aggregated empty data frames.

In step S42, the data frame processing unit 110 cuts out the data header stored in the payload of the received empty data frame. Here, the data length of the data header is predetermined. For example, in the example shown in FIG. 17, since the data header stores 8 bytes of GS, 8 bytes of GD, and 2 bytes of FID, the data length of the data header is 18 bytes. Therefore, in this case, data (that is, each data header) is extracted in units of 18 bytes from the beginning of the payload of the received empty data frame.

In step S43, the data frame processing unit 110 counts the number of data headers aggregated in the received empty data frame. Here, the number of aggregated data headers is represented by “N”. At this time, the variable i is initialized to “1”. The variable i identifies each data header extracted from the empty data frame in this flowchart.

Steps S44 to S49 are executed for each data header extracted from the empty data frame. That is, the data frame processing unit 110 extracts the i-th data header in step S44, and executes the processes in steps S45 to S48.

In steps S45 to S46, the data frame processing unit 110 searches the FID management table 105 based on the FID / GS pair of the i-th data header. Here, entries FID management table 105 is described with reference to FIG. 29 later, from the last update time aging time G _f is deleted at the time of the lapse. In other words, the entry for the FID management table 105, period since the last update time to the aging time G _f has elapsed is present. Incidentally, the aging time _{G f} of FID management table 105 corresponds to a holding period G shown in FIG. 15.

If there is an entry corresponding to the received empty data frame in the FID management table 105, the data frame processing unit 110 extracts from the buffer unit 109 the data frame specified by the above-mentioned FID / GS pair (step S47). Restore. As will be described later with reference to FIG. 24, when receiving a data frame from an adjacent node, the node device holds the data frame in the buffer unit 109. Then, an entry of the FID management table 105 is created using the FID and GS pair of the received data frame. Here, during a period in which an entry exists in the FID management table 105, the corresponding data frame is held in the buffer unit 109. That is, a period in the entry specified by the pair of the above-mentioned FID and GS are present (the period from the last update time until the aging time G _f has elapsed), the corresponding data frame is held by the buffer unit 109 Yes.

In step S48, the data frame processing unit 110 generates an ACK frame corresponding to the data frame extracted in step S47, and requests the transmission unit 102 to transmit the ACK frame. Then, the transmission unit 102 returns the ACK frame to the transmission source node apparatus of the empty data frame. Thereby, the node device that has performed the backtracking recognizes that the backtracking has been successful.

When there is no entry corresponding to the FID management table 105 (step S46: No), the data frame processing unit 110 does not execute steps S47 to S48. That is, in this case, since there is no received data frame corresponding to the empty data frame, the ACK frame corresponding to this received data frame is not returned to the node device that has performed backtracking.

In step S49, the data frame processing unit 110 checks whether or not the variable i has reached the number N of data headers. If the variable i is smaller than N, it is determined that an unselected data header remains. In this case, after the variable i is incremented, steps S44 to S48 are executed. That is, the processing of steps S44 to S48 is executed for the next data header extracted from the aggregated empty data frame. On the other hand, if the variable i reaches N, the processing of this flowchart ends.

Note that if the aggregation of empty data frames is not performed during the backtrack operation, the processing of steps S43, S44, and S49 is not necessary in the flowchart of FIG. Alternatively, “N = 1” may be given in the flowchart of FIG.

As described above, in the frame transmission method according to the embodiment, when the node device (hereinafter referred to as the backtrack execution node device) determines that the transfer of the data frame received from the OLS node device is impossible, the normal transmission to the OLS node device is performed. Send data frame or empty data frame. When the OLS node device receives a normal data frame from the backtrack execution node device, the OLS node device transfers the data frame to another adjacent node device. When the OLS node device receives an empty data frame from the backtrack execution node device, the OLS node device extracts the data frame corresponding to the empty data frame from the buffer unit 109 and transfers it to another adjacent node device. At this time, the OLS node apparatus returns an ACK frame to the backtrack execution node apparatus in any case. Then, the backtrack execution node device ends the backtrack operation.

However, the OLS node device does not return the ACK frame to the backtrack execution node device when the data frame corresponding to the empty data frame received from the backtrack execution node device is not stored in the buffer unit 109. Then, the backtrack execution node device transmits a normal data frame to the OLS node device after a predetermined time has elapsed. Alternatively, in a configuration in which the empty data frame is repeatedly transmitted in the backtrack operation, the backtrack execution node device may transmit the empty data frame to the OLS node device again after a predetermined time has elapsed. Then, the backtrack execution node device may transmit a normal data frame to the OLS node device when the ACK frame cannot be received even though the empty data frame is repeatedly transmitted a predetermined number of times.

In the network according to the embodiment, node devices that can process empty data frames and node devices that cannot process empty data frames may coexist. For example, in the embodiment shown in FIG. 14, it is assumed that the node device X cannot process an empty data frame. Then, it is assumed that the node device a transmits an empty data frame to the node device X in the backtrack operation. In this case, since the node device X cannot process the received empty data frame, it does not return an ACK frame to the node device a. Then, the node device a transmits a normal data frame to the node device X after a predetermined time has elapsed since the empty data frame was transmitted. Then, the node device X transfers the received normal data frame to the node device d. Thus, even when a node device that cannot process an empty data frame is provided in the network, the data frame transfer is not blocked.

Also, in the frame transmission method of the embodiment, the backtrack execution node device (node device a in FIGS. 14 to 15) is configured to send empty data when the elapsed time from the entry time of the target data frame is shorter than the holding period G Send a frame. On the other hand, the OLS node device (node device X in FIGS. 14 to 15) will be described later with reference to FIG. 32, but from the time (last update time) when the target data frame is transmitted to the backtrack execution node device. Until the elapsed time reaches the holding period G, the target data frame is held in the buffer unit 109. Here, assuming that the clocks of the node devices are synchronized, the entry time in the backtrack execution node device is always later than the last update time in the OLS node device. For this reason, if the retention period G has not elapsed since the entry time in the backtrack execution node device, there is a high possibility that the target data frame is retained in the OLS node device. Therefore, when an empty data frame is transmitted from the backtrack execution node device under the above conditions, there is a high possibility that the target data frame held in the buffer unit 109 in the OLS node device is effectively used.

<Flowchart showing operation of each node device>
Next, details of the operation of the node device 100 will be described with reference to the flowcharts shown in FIGS.

FIG. 24 is a flowchart of the frame reception process. The frame reception process is started when the node device 100 is turned on.
In step S201, the reception unit 101 waits until a frame is received. That is, if the receiving unit 101 has not received a frame, step S201 is repeated. When receiving the frame, the receiving unit 101 outputs the received frame to the frame branching processing unit 106, and the process proceeds to step S202.

In step S202, the frame branching processing unit 106 refers to the value of the type field of the frame received by the receiving unit 101 in step S201, and determines the frame type. If the received frame type is a hello frame, the process proceeds to step S203. If the received frame type is a data frame, the process proceeds to step S204. If the received frame type is an ACK frame, the process proceeds to step S206. Note that the empty data frame and the aggregated empty data frame used in the backtrack operation are processed in the same manner as normal data frames in each node device unless otherwise specified. Therefore, in the description related to FIGS. 24 to 41, the “data frame” includes an empty data frame and an aggregated empty data frame unless otherwise specified.

In step S203, the frame branch processing unit 106 outputs the received hello frame to the link management unit 108, and the link management unit 108 performs the hello frame reception process of FIG. Then, the process returns to step S201. Of course, in the multitasking environment in which the MPU 201 in FIG. 4 executes a plurality of tasks corresponding to the units in FIG. 3 in parallel, if the frame branch processing unit 106 outputs a hello frame, it does not wait for the end of the hello frame reception process. The process may move to step S201.

In step S204, the frame branching processing unit 106 stores the data frame received in step S201 in the buffer unit 109. That is, the frame branching processing unit 106 reserves a new entry area in the buffer unit 109, and stores the data frame received in step S201 in the secured area. Further, the frame branching processing unit 106 extracts and stores the GS and FID values from the data frame for the next step S205. Although the buffer unit 109 has a timeout time field as shown in FIG. 8, the timeout time is not yet set at the time of step S204.

In step S205, the frame branching processing unit 106 instructs the data frame processing unit 110 to perform data frame reception processing. When instructed, the frame branching processing unit 106 notifies the data frame processing unit 110 of the GS and FID values of the data frame stored in step S204.

When the node device 100 is a device that does not become a GS (for example, when the node device 100 is a relay-dedicated device), the data frame reception process is as shown in FIGS. On the other hand, when the node device 100 is a type of device that can also be a GS, the data frame reception process is as shown in FIGS. 30 to 32 and FIG.

When the data frame processing unit 110 performs the data frame reception process according to the instruction, the process returns to step S201. Of course, in the multitasking environment, if the frame branch processing unit 106 instructs the data frame processing unit 110 to perform the data frame reception process, the process may proceed to step S201 without waiting for the end of the data frame reception process.

In step S206, the frame branch processing unit 106 outputs the received ACK frame to the ACK processing unit 107, and the ACK processing unit 107 performs the ACK frame reception process of FIG. Then, the process returns to step S201. Of course, in the multitasking environment, when the frame branch processing unit 106 outputs an ACK frame, the process may proceed to step S201 without waiting for the end of the ACK frame reception process.

FIG. 25 is a flowchart of the hello frame reception process in step S203 of FIG. The processing in FIG. 25 is started when a hello frame is output from the frame branching processing unit 106 to the link management unit 108.

In step S301, the link management unit 108 determines whether or not an entry having the same value as the LS of the received hello frame as the node ID exists in the adjacent node management table 103 (see FIG. 9). If an entry is found, the process proceeds to step S302. If no entry is found, the process proceeds to step S303.

Note that the “received hello frame” in the description of FIG. 25 is the hello frame received by the receiving unit 101 in step S201 of FIG. That is, the “received hello frame” in the description of FIG. 25 is a hello frame that is output from the frame branching processing unit 106 to the link management unit 108 in step S202 and triggers the start of the processing of FIG.

In step S302, the link management unit 108 sets the current time as the last update time of the entry found in step S301. Then, the process of FIG. 25 ends.
For example, as a result of step S302 is executed in the node device _{N 2,} in the adjacent node management table _{103-N 2} as shown in FIG. 9, the value of the last update time field corresponding to the node ID of _{N 1} is _{TA 2,1} And updated. As a result, the node device N ₂ can store “at the time TA _2,1 , the node device N ₂ can recognize the node device N ₁ as an adjacent node device”.

On the other hand, if no entry is found in step S301, it means that a hello frame has been received from a new node device that has not been recognized as an adjacent node device until now. Therefore, in the subsequent steps S303 to S308, processing for registering the new node device as an adjacent node device is performed.

In step S <b> 303, the link management unit 108 adds a new entry to the adjacent node management table 103. In step S304, the link management unit 108 sets the LS value of the received hello frame and the current time in the new entry added in step S303. For example, when the hello frame 312 of FIG. 7 is received for the first time, the node device N ₂ sets N ₃ which is the LS value of the hello frame 312 in the node ID field of the new entry, and the last update time field of the new entry Set the current time to.

Subsequently, in step S305, the link management unit 108 includes the weighting table 104-i (1 ≦ i ≦ M) that has not yet been focused on in the weighting tables 104-1 to 104-M (see FIGS. 10 and 11). ) Is determined. If all the weighting tables 104-1 to 104-M have already been focused on, the processing in FIG. 25 ends. If there is a weighting table 104-i that has not yet been focused on, the processing moves to step S306.

In step S306, the link management unit 108 pays attention to the next weighting table from among the weighting tables 104-1 to 104-M that have not been noticed yet. Hereinafter, for convenience of explanation, it is assumed that the weighting table 104-i is noted in step S306.

In step S307, the link management unit 108 adds a new entry to the weighting table 104-i of interest. Further, in step S308, the link management unit 108 sets the LS value, initial weight value, and current time of the received hello frame in the LD, weight, and last update time fields of the new entry added in step S307. Set each. The initial weight value is a constant arbitrarily determined according to the embodiment.

In the first embodiment, as described above, the weight value is 0 or more and 1 or less, and 1 is a special value indicating that the LD cannot be selected. Therefore, the initial weight value is an arbitrary value between 0 and 1 It's okay. More specifically, the initial weight value may be 0.5, for example. For example, the first entry of the weighting table 104-1-N ₃ shown at the top of FIG. 11 may be created as follows (however, in that case, the first entry is the last update time of the entry, the last update time T _a of the other two entries are set different values, not exactly the same as FIG. 11).

Node device _{N 7} weighting table _{104-1-N 3} associated with a GD already exists.
However, the node device N ₃ has not recognized the node device N ₂ as an adjacent node device until now.

The node device N ₃ has received a hello frame from the node device N ₂ for the first time.
In the above situation, the weighting table 104-1-N ₃ was noted in step S306.

Therefore, in step S308, N ₂ that is the LS value of the received hello frame is set in the LD field of the new entry, and 0.5 that is the initial weight value is set in the weight field of the new entry.
After execution of step S308, the process returns to step S305.

FIG. 26 is a flowchart of the hello frame transmission process. The process of FIG. 26 is executed by the hello frame generation unit 112 in parallel with the process of FIG. Specifically, when the node device 100 is powered on, the hello frame generation unit 112 starts the process of FIG.

In step S401, the hello frame generation unit 112 determines whether or not the current time is the scheduled transmission time. If the current time is the scheduled transmission time, the process proceeds to step S402. If the current time is not the scheduled transmission time, the process returns to step S401. That is, the hello frame generation unit 112 waits until the scheduled transmission time.

For example, the transmission time ΔT _hello between the reference time T _ref and the hello frame may be determined in advance. Further, the hello frame generation unit 112 can refer to the current time _{T now} based on MPU201 clock of Figure 4, for example. The hello frame generation unit 112 may determine that “the current time is the scheduled transmission time” only when Z in Expression (4) is an integer.
Z = (T _ref −T _now ) / ΔT _hello (4)
For example, the reference time T _ref may be a predetermined constant or the time when the node device 100 is turned on. Further, the transmission interval ΔT _hello can be appropriately determined according to the embodiment, and may be a relatively long time such as 10 seconds, for example.

In step S402, the hello frame generation unit 112 requests the FID generation unit 113 to generate a new FID, and the FID generation unit 113 generates a new FID. For example, the FID may be a sequence number, and the FID generation unit 113 may be realized using a counter circuit. Of course, the FID generation unit 113 may be realized by the MPU 201 executing a program.

In step S402, the hello frame generation unit 112 further generates a hello frame using the FID generated by the FID generation unit 113. For example, the hello frame 312 in FIG. 7 is generated as follows. That is, the FID generator _{113-N 3} of the node device _{N 3,} and generates a value of _{F b} as a new FID. Then, the hello frame generation unit 112-N ₃ of the node device N ₃ generates a new hello frame 312.

At that time, in the hello frame 312, the hello frame generation unit 112-N ₃ sets a predetermined value of 0xFFFFFF in the LD, sets N ₃ which is its own node ID in the LS and GS, and sets a predetermined value of 0x000000 in the GD. Set the value. Further, the hello frame generation unit _{112-N 3,} in the hello frame 312, the FID sets the value _{F b} generated by the FID generator _{113-N 3,} the type sets a predetermined value H.

When the hello frame is generated in step S402 as described above, subsequently, in step S403, the hello frame generation unit 112 requests the transmission unit 102 to transmit the generated hello frame, and the transmission unit 102 transmits the hello frame. Send. Then, the process returns to step S401.

Subsequently, aging processing of various tables will be described with reference to FIGS. Each aging process may be started, for example, in response to an interrupt signal from the timer IC 203 in FIG.

FIG. 27 is a flowchart of the aging process of the adjacent node management table 103. For example, the timer IC203 outputs an interrupt signal at predetermined intervals I _a link management unit 108, link management unit 108 the interrupt signal as a trigger may perform processing of FIG. 27 at a predetermined interval I _a.

In step S501, the link management unit 108 pays attention to the first entry in the adjacent node management table 103 (see FIG. 9). Hereinafter, in the description related to FIG. 27, the entry in the adjacent node management table 103 focused on by the link management unit 108 is referred to as “target entry”.

In step S502, the link management unit 108 determines whether the difference between the current time and the last update time of the entry of interest is equal to or greater than _a predetermined value Ga. Note that, depending on the embodiment, G _a = I _a may be satisfied, G _a <I _a may be satisfied, or G _a > I _a may be satisfied.

If the difference between the current time and the last update time of the target entry is greater than or equal to _a predetermined value Ga, the process proceeds to step S503. On the other hand, the current time, the difference between the last update time of the target entry, is less than the predetermined value G _a, the process proceeds to step S505.

In step S503, the link management unit 108 deletes the entry having the same value as the node ID of the entry of interest as the LD from the weighting table 104. For example, interest entry, if a third entry of the adjacent node management table 103-N ₃ in FIG. 9, the value of the node ID of the target entry is N _5. Accordingly, in step S503, the link management unit 108 deletes the entry whose LD value is N ₅ from each of the weighting tables 104-1-N ₃ to 104-MN ₃ . For example, in step S503, the third entry in the weighting table 104-1-N _{3 and} the third entry in the weighting table 104-2-N ₃ in FIG. 10 are deleted.

In step S <b> 504, the link management unit 108 deletes the target entry from the adjacent node management table 103. Then, the process proceeds to step S505.
In step S <b> 505, the link management unit 108 determines whether an entry that has not been noticed still remains in the adjacent node management table 103. If the link management unit 108 finishes paying attention to all entries in the adjacent node management table 103, the processing in FIG. On the other hand, if an entry not yet noticed by the link management unit 108 remains in the adjacent node management table 103, the process proceeds to step S506.

In step S506, the link management unit 108 pays attention to the next entry among the entries not yet noticed in the adjacent node management table 103. Then, the process returns to step S502.

27, when the node device 100 stops receiving the hello frame from the node device that has been recognized as the adjacent node device until now, “the node device is no longer adjacent to the node device 100. It will be possible to recognize that there is no. That is, the processing in FIG. 27 allows the node device 100 to appropriately manage the adjacent node device as a potential LD candidate following the environmental change.

The predetermined interval I _a and the predetermined value G _a are desirably determined as appropriate according to the embodiment in accordance with the ease of change of the environment. In the first embodiment, the same hello frame transmission interval ΔT _hello is set for all the node devices in the network, and the predetermined value G _a which is the aging time of the adjacent node management table 103 is G _a > ΔT _hello is satisfied.

FIG. 28 is a flowchart of the aging process of the weighting table 104. For example, the timer IC203 outputs an interrupt signal at predetermined intervals I _w to the data frame processing unit 110, the data frame processing unit 110 the interrupt signal as a trigger may perform processing of FIG. 28 at a predetermined interval I _w.

In step S601, the data frame processing unit 110 pays attention to the first weighting table 104-1 in the weighting table 104 (see FIGS. 10 and 11). Hereinafter, in the description related to FIG. 28, the weighting table focused by the data frame processing unit 110 is represented by the reference numeral “104-i” (1 ≦ i ≦ M) and is referred to as “target table”. Immediately after execution of step S601, i = 1.

In step S602, the data frame processing unit 110 pays attention to the first entry of the attention table 104-i. Hereinafter, an entry that the data frame processing unit 110 pays attention to in the attention table is referred to as a “notice entry”.

Then the data frame processing unit 110 in step S603, the current time, the difference between the last update time of the target entry, it is determined whether more than a predetermined value G _w. Depending on the embodiment, G _w = I _w , G _w <I _w , or G _w > I _w may be used.

And the current time, the difference between the last update time of the target entry, equal to or greater than a predetermined value G _w, the process proceeds to step S604. On the other hand, the current time, the difference between the last update time of the target entry, is less than the predetermined value G _w, the process proceeds to step S605.

In step S604, the data frame processing unit 110 deletes the target entry from the target table 104-i. Then, the process proceeds to step S605.
In step S605, the data frame processing unit 110 determines whether or not there is an entry that has not been noticed yet in the attention table 104-i. If the data frame processing unit 110 has finished paying attention to all entries in the attention table 104-i, the process proceeds to step S607. On the other hand, if an entry not yet noticed by the data frame processing unit 110 remains in the attention table 104-i, the process proceeds to step S606.

In step S606, the data frame processing unit 110 pays attention to the next entry among the entries not yet noticed in the attention table 104-i. Then, the process returns to step S603.

In step S607, the data frame processing unit 110 determines whether there is an entry in the attention table 104-i. As a result of repeating steps S603 to S606, when there are no more entries in the attention table 104-i, the process proceeds to step S608. On the other hand, if one or more entries exist in the attention table 104-i, the process proceeds to step S609.

In step S608, the data frame processing unit 110 deletes the attention table 104-i in which no entry exists. Then, the process proceeds to step S609.
In step S609, the data frame processing unit 110 determines whether or not a weighting table that has not been noticed remains in the weighting table 104. If the data frame processing unit 110 has finished paying attention to all the weighting tables 104-1 to 104-M, the processing in FIG. 28 ends. On the other hand, if the weighting table 104-j (1 ≦ j ≦ M) not yet noticed by the data frame processing unit 110 remains in the weighting table 104, the process proceeds to step S610.

In step S610, the data frame processing unit 110 pays attention to the next weighting table 104-j that has not been noticed in the weighting table 104 (that is, selects the weighting table 104-j as the attention table 104-i). Then, the process returns to step S602.

With the aging process of FIG. 28 described above, the node device 100 does not fall into a situation in which “the effects of past failures are accumulated and any adjacent node device cannot be selected as an LD”.

For example, in the example of FIG. 6, it is assumed that a failure occurs in the link between the node devices N ₆ and N ₇ after step S112, and the link between the node devices N ₄ and N ₇ is recovered from the failure. To do. If the aging process of FIG. 28 is not performed, the data frame can be transmitted through the path <N ₁ , N ₂ , N ₃ , N ₄ , N ₇ >, for example, by actually recovering from the failure. However, this route will not be selected as a result of autonomous distributed cooperation. However, if the aging process of FIG. 28 is performed, the path <N ₁ , N ₂ , N ₃ , N ₄ , N ₇ > can be selected in the situation assumed above.
The predetermined interval I _w and a predetermined value G _w above, in accordance with the change easiness environment, it is desirable to be appropriately determined depending on the embodiment.
FIG. 29 is a flowchart of the aging process of the FID management table 105. For example, the timer IC203 outputs an interrupt signal at predetermined intervals I _f to the data frame processing unit 110, the data frame processing unit 110 may perform the process in FIG. 29 at a predetermined interval I _f the interrupt signal as a trigger.

In step S701, the data frame processing unit 110 pays attention to the first entry in the FID management table 105 (see FIGS. 12 and 13). Hereinafter, in the description related to FIG. 29, the entry that the data frame processing unit 110 is paying attention to is referred to as a “target entry”.

Then the data frame processing unit 110 in step S702, the current time, the difference between the last update time of the target entry, it is determined whether more than a predetermined value G _f. Depending on the embodiment, G _f = I _f , G _f <I _f , or G _f > I _f may be used.

Also, for reasons which will be described later with respect to step S807 of FIG. 31, in the first embodiment, the predetermined value _{G w} is the aging time of the weighting table 104, a predetermined value _{G f} is the aging time of the FID management table 105, G _f <G _w is satisfied.

And the current time, the difference between the last update time of the target entry, equal to or greater than a predetermined value G _f, the process proceeds to step S703. On the other hand, the current time, the difference between the last update time of the target entry, is less than the predetermined value G _f, the process proceeds to step S704.

In step S703, the data frame processing unit 110 deletes the entry of interest from the FID management table 105. Then, the process proceeds to step S704.
In step S <b> 704, the data frame processing unit 110 determines whether an entry that has not been noticed still remains in the FID management table 105. If the data frame processing unit 110 has finished paying attention to all entries in the FID management table 105, the processing in FIG. 29 ends. On the other hand, if an entry not yet noticed by the data frame processing unit 110 remains in the FID management table 105, the process proceeds to step S705.

In step S705, the data frame processing unit 110 pays attention to the next entry among the entries not yet noticed in the FID management table 105. Then, the process returns to step S702.

With the aging process of FIG. 29 described above, it is possible to prevent a situation such as “the number of entries in the FID management table 105 continues to increase and the storage area is exhausted”. Note that the predetermined value G _f is determined so as to be equal to or longer than the length of time predicted for the data frame to reach the GD from the GS in the worst case in which backtracking occurs many times. It may be. In general, larger the network, it is desirable to set larger the predetermined value G _f.

30 to 35 are flowcharts of the data frame reception process in step S205 of FIG. For convenience of explanation, first, data frame reception processing when the node device 100 is of a type different from GS will be described with reference to FIGS. 30 to 35. FIG. In the case where the node device 100 is of a type that can also be a GS, the part of FIGS. 34 to 35 is replaced with the process of FIG. 41 described later.

When instructed to perform the data frame reception processing from the frame branching processing unit 106 in step S205 of FIG. 24, the data frame processing unit 110 starts the processing of FIG. As described above, the instruction from the frame branch processing unit 106 is accompanied by notification of the GS and FID values of the received data frame.

In step S801, the data frame processing unit 110 determines whether the LD value of the received data frame is its own node ID. If the LD value of the received data frame is not the own node ID, the process proceeds to step S802. If the LD value of the received data frame is the own node ID, the process proceeds to step S801a.

In the description of the data frame reception process, “received data frame” is received by the reception unit 101 in step S201 in FIG. 24, stored in the buffer unit 109 in step S204, and triggered by the start of the process in FIG. This is the data frame.

Further, when the frame branching processing unit 106 instructs the data frame processing unit 110 to start the data frame reception processing, the frame branching processing unit 106 notifies the data frame processing unit 110 of the GS and FID values of the received data frame. Therefore, the data frame processing unit 110 can find an entry including the received data frame by searching the buffer unit 109 using the notified GS and FID values as keys. Therefore, the data frame processing unit 110 can read the value of each field included in the header of the received data frame from the found entry.

More precisely, in step S801, the data frame processing unit 110 first reads and stores the value of each field included in the header of the received data frame from the buffer unit 109 as described above. Then, the stored LD value (that is, the LD value of the received data frame) is compared with its own node ID. Note that the own node ID, which is the node ID of the node device 100 itself, is recorded in advance in, for example, the flash memory 205 of FIG. 4, so that the data frame processing unit 110 can refer to the own node ID.

When the LD value of the received data frame is different from the own node ID, the node device 100 has received a data frame unrelated to the node device 100 by accident. Therefore, in step S802, the data frame processing unit 110 discards the received data frame. That is, the data frame processing unit 110 deletes the entry of the buffer unit 109 found in step S801. Then, the data frame reception process ends.

On the other hand, if the LD value of the received data frame is equal to its own node ID, the data frame processing unit 110 refers to the value of the type field of the received frame in step S801a, and the frame type is an empty data frame and an aggregation. It is determined whether it is any empty data frame. If it is determined that the type of the received frame is either an empty data frame or an aggregated empty data frame, the process proceeds to step S801b.

In step S801b, for the received empty data frame or aggregated empty data frame, the data frame processing unit 110 executes the above-described empty data frame reception process of FIG. Then, the process proceeds to step S801c.

In step S801c, the data frame processing unit 110 determines whether there is a data frame extracted (restored) from the buffer unit 109 in the empty data frame reception process. If it is determined that there is a data frame extracted (restored) from the buffer unit 109, the process proceeds to step S804. Hereinafter, this extracted (restored) data frame is treated as a received data frame. If there are a plurality of extracted (restored) data frames, the data frame receiving process from step S804 onward is executed for each data frame.

If it is determined in step S801c that there is no data frame extracted (restored) from the buffer unit 109, the data frame reception process ends.
If it is determined in step S801a that the type of the received frame is not one of the empty data frame and the aggregated empty data frame, that is, if it is a normal data frame, the process proceeds to step S803.

In step S803, the data frame processing unit 110 generates an ACK frame and requests the transmission unit 102 to transmit the ACK frame. Then, the transmission unit 102 transmits an ACK frame.

For example, when the node device N ₃ receives the data frame 303 in FIG. 7, the data frame processing unit 110-N ₃ of the node device N ₃ generates the ACK frame 322 in FIG. 7 in step S803. Then, the transmission unit 102-N ₃ transmits the ACK frame 322.

Specifically, the data frame processing unit 110-N ₃ sets N ₂ which is the LS value of the received data frame 303 to the LD of the ACK frame 322, and sets its own node ID (that is, the node of the node device N ₃ itself) ID N ₃ ) is set in LS of ACK frame 322. Further, since the ACK frame 322 is irrelevant except for the node device N ₂ which is the LS of the corresponding data frame 303, the data frame processing unit 110-N ₃ has a special value representing null in the GD of the ACK frame 322. Set 0x000000.

Further, the data frame processing unit 110-N ₃ receives the ACK frame 322 so that the node device N ₂ that has received the ACK frame 322 can recognize that the “ACK frame 322 is an ACK frame for the data frame 303”. Set GS and FID. That is, the data frame processing unit _{110-N 3} is the GS and FID of the ACK frame 322, respectively, to set the value _{N 1} and _{F a} of GS and FID data frame 303 received.

Then, the data frame processing unit 110-N ₃ sets a predetermined value A indicating “ACK frame” as the type of the ACK frame 322. In step S803, the data frame processing unit 110-N ₃ generates the ACK frame 322 as described above, and the transmission unit 102-N ₃ transmits the ACK frame 322.

Subsequently, in step S804, the data frame processing unit 110 determines whether the GD value of the received data frame is the own node ID. If the GD value of the received data frame is the own node ID, the process proceeds to step S805. On the other hand, if the GD value of the received data frame is different from the own node ID, the process proceeds to step S806 in FIG.

In step S805, the data frame processing unit 110 passes the payload of the received data frame to the upper layer processing unit 111, and ends the data frame reception process. Specifically, the data frame processing unit 110 extracts the payload from the entry of the buffer unit 109 found in step S801, outputs the payload to the upper layer processing unit 111, and deletes the entry from the buffer unit 109. Then, the data frame reception process ends.

For example, in the node device _{N 7} receives the data frame from the node device _{N 6} at step S112 of FIG. 6, the payload of the received data frame is output to the upper layer processing section _{111-N 7,} upper layer processing section 111-N ₇ is processed.

The processing after step S806 in FIG. 31 is executed when the LD value of the received data frame is equal to the own node ID and the GD value of the received data frame is different from the own node ID.

In step S806, the data frame processing unit 110 searches the FID management table 105 using the FID and GS values of the received data frame as search keys. As described above, the FID and GS values of the received data frame are notified from the frame branch processing unit 106 at the start of the processing of FIG.

Subsequently, in step S807, the data frame processing unit 110 determines whether or not the search result entry in step S806 has been hit. If the entry is hit, it means that the same data frame as the data frame that the node device 100 has transmitted before has been received, and therefore the process proceeds to step S808. On the other hand, if the entry is not hit, it means that a data frame that has not been transmitted by the node device 100 has been received, and the process moves to step S810.

To be exact, even if “the same data frame as the data frame that the node device 100 has transmitted before has been received, but the entry to be searched has already disappeared due to aging”, the entry is a hit. do not do. Such as if does not occur, based on such worst time estimate that backtracking is repeated in the network, be suitably aging time for the FID management table 105 G _f is defined desirable.

In step S808, the data frame processing unit 110 takes out the LD and OLS values of the entry in the FID management table 105 hit in the search in step S806, and stores them in a storage area such as the DRAM 204 in FIG.

Subsequently, in step S809, the data frame processing unit 110 refers to a weighting table corresponding to the GD value of the received data frame (hereinafter referred to by the reference numeral “104-i” in the description of FIGS. 31 to 35). Update as follows: That is, the data frame processing unit 110 changes the weight corresponding to the LD extracted in step S808 to the maximum value in the weighting table 104-i. In the first embodiment, the maximum value of the weight is 1. After changing the weight, the process proceeds to step S817.

When the processing proceeds to steps S807, S808, and S809, it is found that an entry corresponding to the LD extracted in step S808 exists in the weighting table 104-i corresponding to the GD value of the received data frame. Is guaranteed. The reason is as follows.

As described with reference to FIGS. 12 and 13, the last update time in the entry of the FID management table 105 is set when the data frame is transmitted. In addition, as described with reference to FIG. 29, the aging time Gf of the FID management table 105 is set to be longer than the time predicted in the worst case, for example. Therefore, when the data frame transmitted in the past by the node device 100 is received by the node device 100 through the network, it is guaranteed that the entry corresponding to the data frame still remains in the FID management table 105. .

Then, as described with reference to FIG. 11, when the data frame is transmitted and the ACK frame is returned, the weight is updated, and the weight is updated in each entry in the weighting tables 104-1 to 101-M. Sometimes the last update time is also set. Therefore, the following (E1) to (E5) are obtained in time series.

(E1) A data frame in which the GD value is N _GD , the GS value is N _GS , the LD value is N _LD , and the FID value is F _c is transmitted from the node device 100. At this time, the last update time is set in the FID management table 105. For example, in the node device N ₃ in FIG. 6, the last update time T ₁₀₃ is set in the entry E ₃ in FIG. 12 in step S103.

(E2) When the ACK frame for the data frame is received, the weight of the entry whose LD field value is N _LD is updated in the weighting table 104-i corresponding to the node device _NGD . At this time, the last update time of the entry is set. For example, in the node device N ₃ , as shown in FIG. 11, the last update time of the entry whose LD field value is N ₄ in the weighting table 104-1 -N ₃ is set to T _b in step S103a.

(E3) the value of GS is in _{N GS,} the value of FID is the same data frame _{F c,} it is received by the node device 100. For example, the node device _{N 3} in step S106 in FIG. 6 receives the data frame. Since there is no possibility that the value of GD of the data frame is rewritten when the relay, the value of GD of the data frame received by (E3), of course from the (E1), a N _GD.

(E4) from the time of the (E1), aging time _{G f} of FID management table 105 has elapsed.
(E5) from the time of the (E2), aging time _{G w} of the weighting table 104 has elapsed.

As described above, the time point (E3) is before the time point (E5). Therefore, at the time of (E3), the existence of an entry whose LD field value is N _LD is guaranteed in the weighting table 104-i corresponding to the node device N _GD . For example, in the above example, the existence of an entry in the weighting table 104-1-N ₃ whose LD field value is N ₄ is guaranteed at the time of step S106 in FIG. Here, "time of step S106" is more particularly that at the time when the process of step S809 in the data frame reception processing triggered by the reception in step S106, the node device N ₃ executes It is.

Therefore, when an entry is found in the FID management table 105 by the search in step S806 in FIG. 31, in step S809, an entry corresponding to the LD extracted in step S808 always exists in the weighting table 104-i. Therefore, in step S809, the data frame processing unit 110 sets the weight value to the maximum value in the entry whose existence is guaranteed.

On the other hand, if no entry is found in step S806, in step S810, the data frame processing unit 110 stores the LS value of the received data frame as an OLS in a storage area such as the DRAM 204 in FIG. . In step S811, the data frame processing unit 110 searches the weighting table 104 using the GD value of the received data frame as a search key.

Subsequently, in step S812, the data frame processing unit 110 determines whether the table is hit as a result of the search in step S811.
If a weighting table corresponding to the GD value of the received data frame exists in the weighting table 104, the process proceeds to step S812a. Note that the reference sign “104-i” introduced in step S809 indicates the weighting table corresponding to the GD value of the received data frame, and thus the table hit as a result of the search in step S811 is also “weighting table 104- i ".

On the other hand, if the weighting table corresponding to the GD value of the received data frame does not exist in the weighting table 104, the process proceeds to step S813.
In step S812a, the data frame processing unit 110 adjusts the weighting table 104-i hit in the search in step S811. The weighting table adjustment process in step S812a is a process for neutralizing the side effects of the aging process, which will be described later in detail with reference to FIG.

As a result of step S812a, it is guaranteed that entries corresponding to all adjacent node devices managed in the adjacent node management table 103 exist in the weighting table 104-i. Then, the process proceeds to step S817.

In step S813, the data frame processing unit 110 adds a new weighting table corresponding to the GD value of the received data frame. Note that the table added in step S813 is also the “weighting table 104-i”.

In step S814, the data frame processing unit 110 sets the GD value of the received data frame as the GD of the weighting table 104-i in the new weighting table 104-i.

Further, in step S815, the data frame processing unit 110 creates as many new entries as the number of entries in the adjacent node management table 103 in the new weighting table 104-i.

In step S816, the data frame processing unit 110 sets the node ID, initial weight value, and current time of each entry in the adjacent node management table 103 in each entry created in step S815.

A specific example of the above steps S811 to S816 is as follows.
For example, when receiving the data frame 303 of FIG. 7 in step S102 in FIG. 6 from the node device _{N 2,} the weighting table _{104-N 3} of the node device _{N 3} are weighting table _{104-1-N 3} in FIG. 11 Suppose that it did not exist. Then, the data frame processing unit 110-N _{3 of} the node device N ₃ searches the weighting table 104-N ₃ in step S811 using N ₇ which is the GD value of the data frame 303 received by the node device N ₃ as a search key. Even so, the table does not hit.

Therefore, the data frame processing unit 110-N ₃ newly creates the weighting table 104-1-N ₃ in step S813, and sets N ₇ to the GD of the weighting table 104-1-N _{3 in} step S814. In step S815, the data frame processing unit 110-N ₃ creates the same number (ie, three) new entries as the adjacent node management table 103-N _{3 in} FIG. 9 in the weighting table 104-1-N ₃ .

Here, the node ID of each entry of the adjacent node management table 103-N ₃ is N ₂ , N ₄ and N _{5 as shown} in FIG. Therefore, in step S816, the data frame processing unit 110-N ₃ sets N ₂ , N _4, and N ₅ as LDs in each of the three entries created in step S815. The data frame processing unit 110-N ₃ sets an initial weight value of 0.5 in the weight fields of these three entries, and sets the current time in the last update time fields of these three entries. Set.

As a result of the above steps S813 ~ S 816, the weighting table _{104-1-N 3,} such as the first stage of FIG. 11 is added in the weighting table _{104-N 3.}
Here, the description returns to the general processing of FIG. 31 from the description of the specific example. Step S817 is executed after step S809 is executed, after step S816 is executed, or after it is determined in step S812 that the table is hit in the search of step S811. Therefore, when step S817 is executed, the existence of the weighting table 104-i corresponding to the GD value of the received data frame is guaranteed.

Therefore, in step S817, the data frame processing unit 110, in the weighting table 104-i corresponding to the GD value of the received data frame, the LD value associated with the minimum weight among the LDs different from the OLS. To get.

That is, the data frame processing unit 110 selects, in the weighting table 104-i, the entry having the smallest weight value from the entries having as the LD a value different from the OLS value stored in step S808 or S810. Then, the data frame processing unit 110 stores the LD and weight values of the selected entry in a storage area such as the DRAM 204 in FIG.

Subsequently, in step S818, the data frame processing unit 110 determines whether one of the following two conditions (F1) and (F2) is satisfied.
(F1) The weight corresponding to the LD value acquired in step S817 (or S829 described later) is the maximum weight value (1.0 in the first embodiment).

(F2) All data frame transfers to LDs different from the OLS value stored in step S808 or S810 have failed (including the case where the LD in the weighting table 104-i originally has only OLS). .

When the condition (F1) or (F2) is satisfied, there is no longer any adjacent node device that can be selected as the LD, so the process moves to step S830 in FIG. In this case, a backtrack operation is performed.

On the other hand, when neither of the conditions (F1) and (F2) is satisfied, there are still adjacent node devices that can be selected as the LD. In other words, there is at least one adjacent node device that does not correspond to any of (G1) to (G4). Then, the node ID of the adjacent node device that can be selected as the LD is acquired in step S817 (or S829 described later).

(G1) Since it is determined that the path ahead from the adjacent node device is a dead path or a loop, the adjacent node device is associated with the maximum weight.
(G2) Since the results of the failure to transmit data frames addressed to the same GD to the adjacent node device have accumulated in the past, the adjacent node device is associated with the maximum weight.

(G3) As a result of trying to transmit a data frame to the adjacent node device in this data frame reception process, it was determined that the transmission failed. That is, the ACK frame cannot be received from the adjacent node device that transmitted the data frame even after a predetermined time.

(G4) The adjacent node device is OLS.
Therefore, if it is determined in step S818 that neither of the conditions (F1) and (F2) is satisfied, the process proceeds to step S819. The processing after step S819 is processing for attempting to transfer the data frame to the adjacent node device identified by the acquired LD value.

In step S819, the data frame processing unit 110 creates a new data frame and outputs it to the transmission unit 102 as follows, and the transmission unit 102 transmits the created data frame.

Specifically, the data frame processing unit 110 designates the LD value acquired in step S817 (or S829 described later) as the LD of the new data frame, and designates its own node ID as the LS of the new data frame. . In addition, the data frame processing unit 110 copies the values of the GD, GS, FID, type, and length fields and the payload from the received data frame to a new data frame. As described above, the “received data frame” is the data frame stored in the entry in the buffer unit 109 found in step S801 or extracted (restored) from the buffer unit 109 in step S47 of FIG. Data frame.

After the transmission in step S819, the process proceeds to step S820, and the data frame processing unit 110 updates the timeout time of the buffer unit 109. That is, in the buffer unit 109, the data frame processing unit 110 sets the time T _timeout of Expression (5) as the timeout time of the entry storing the received data frame.
T _timeout = T _now + T _wait (5)
In Equation (5), time _Tnow is the current time, and time _Twait is the ACK frame waiting time.

In step S821, the data frame processing unit 110 adds an entry to the FID management table 105 in steps S823 and S824, which will be described later, in the search of the FID management table 105 in step S806. Check whether the value is set. That is, the data frame processing unit 110 confirms whether or not an entry having GS and FID having values equal to the GS and FID values of the received data frame exists in the FID management table 105.

If the entry is hit in the search in step S806, or if a value is set by adding a new entry to the FID management table 105 in steps S823 and S824, the current data frame reception process has been executed in the past. This is a process triggered by reception of the same data frame as that transmitted by itself. Therefore, the data frame processing unit 110 subsequently executes step S822. On the other hand, if the entry is not hit in the search in step S806, and if a value is not set by adding a new entry to the FID management table 105 in steps S823 and S824, the node device 100 receives for the first time. The first transfer of data frames is being attempted. Therefore, the process proceeds to step S823.

In step S822, the data frame processing unit 110 updates the entry hit in the search in step S806. Specifically, the data frame processing unit 110 sets the LD value of the data frame transmitted in step S819 in the LD field in the entry hit in the search in step S806, and sets the current value in the last update time field. Set the time. Then, the process proceeds to step S825.

Note that step S822 is executed when it is determined “Yes” in step S821. Here, the situation determined as “Yes” in step S821 is that the data frame transmitted in step S819 has been transmitted to another adjacent node device in the past, and the corresponding ACK frame is received from the adjacent node device. It happens when you are. That is, at the time when step S822 is executed, “already” should be set in the ACK reception flag of the entry in the FID management table 105. Therefore, when the data frame processing unit 110 transmits the data frame in step S819, the data frame processing unit 110 updates the ACK reception flag to “NULL” in step S822.

On the other hand, in step S823, the data frame processing unit 110 adds a new entry to the FID management table 105. In step S824, the data frame processing unit 110 sets a value for the new entry. Specifically, the data frame processing unit 110 copies the value of the data frame transmitted in step S819 to the FID field, GS field, and LD field in the new entry created in the FID management table 105 shown in FIG. To do. In addition, in the new entry, the data frame processing unit 110 sets the current time in the entry time field and the last update time field, and copies the OLS value stored in step S810 to the OLS field. Then, the process proceeds to step S825. Note that “NULL” is set in the ACK reception flag, and “zero” is set in the empty data transmission count field and the normal data transmission count field.

Note that the entry time recorded at this time is used to determine whether to transmit a normal data frame or an empty data frame in the backtrack operation. For example, in the sequence diagram shown in FIG. 15 and the flowchart shown in FIG. 19, this entry time is used as “time TE”.

In step S825, the data frame processing unit 110 waits for notification of the success or failure of transmission in step S819. For example, when the data frame processing unit 110 is realized by the MPU 201 of FIG. 4 that executes a thread of a predetermined program, the thread may sleep in step S825. In this case, the notification of “success in transmission” or “transmission failure” is a process for causing a thread.

If the transmission in step S819 is successful, an ACK frame is returned from the adjacent node device designated as the LD in the data frame transmitted in step S819. Then, the ACK processing unit 107 performs the process of FIG. 37 described later, and notifies the data frame processing unit 110 of “successful transmission”. As a result, the ACK flag of the corresponding entry in the FID management table 105 is updated to “completed”.

Further, the transmission failure in step S819 means that the node device 100 does not receive an ACK frame from the adjacent node device designated as LD in the data frame transmitted in step S819 even when the time T _timeout in Expression (5) is reached. It is not received. The reception of the ACK frame is monitored by the processing of FIG. 38 described later by the ACK processing unit 107. If the ACK frame is not received even when the timeout time T _timeout is reached, the ACK processing unit 107 notifies the data frame processing unit 110 that “ "Send failed". In this case, the ACK flag of the corresponding entry in the FID management table 105 is held as “NULL”.

When the data frame processing unit 110 receives a “transmission success” or “transmission failure” notification from the ACK processing unit 107 after waiting in step S825, the process proceeds to step S826.

In step S826, based on the notification received from the ACK processing unit 107, the data frame processing unit 110 determines whether the transmission in step S819 is successful. If the transmission is successful, the process proceeds to step S827. If the transmission fails, the process proceeds to step S828.

If the transmission is successful, in step S827, the data frame processing unit 110 decreases the weight corresponding to the pair of GD and LD of the data frame transmitted in step S819 in the weighting table 104. Here, it should be noted that the GD of the data frame is not rewritten by the transfer. In other words, in step S827, the data frame processing unit 110 performs weighting in the weighting table 104-i corresponding to the GD of the received data frame. Update.

That is, the data frame processing unit 110 searches the weighting table 104-i for an entry having the LD value acquired in step S817 (or step S829 described later) as an LD, and decreases the weight value of the found entry. Decreasing the weight value means increasing the priority of the corresponding LD.

Here, assuming that the _current weight value of the found entry is W _current , the data frame processing unit 110 may update the weight value of the found entry to, for example, W _revised in Expression (6) in step S827. .
W _revised = max (W _min ,
W _current -ΔW _success ) (6)
In Equation (6), W _min is the minimum value of weight, and W _min = 0 in the first embodiment. Further, ΔW _success is a predetermined amount to reduce the weight when transmission is successful, and can be appropriately determined according to the embodiment. For example, ΔW _success = 0.1 may be used.

Further, in step S827, the data frame processing unit 110 sets the current time as the last update time in the entry of the weighting table 104-i having the LD value acquired in step S817 (or step S829 described later) as the LD. Then, the data frame reception process ends.

On the other hand, if the transmission fails, in step S828, the data frame processing unit 110 increases the weight corresponding to the pair of GD and LD of the data frame transmitted in step S819 in the weighting table 104. That is, in step S828, the data frame processing unit 110 searches the weighting table 104-i for an entry having the LD value acquired in step S817 (or later-described step S829) as an LD, and increases the weight value of the found entry. To do. Increasing the weight value means lowering the priority of the corresponding LD.

For example, in step S828, the data frame processing unit 110 may update the weight value of the found entry to W _revised in Expression (7).
W _revised = min (W _max ,
W _current + ΔW _failure ) (7)
In Equation (7), W _max is the maximum weight value, and W _max = 1 in the first embodiment. Further, ΔW _failure is a predetermined amount to increase the weight when transmission fails, and can be appropriately determined according to the embodiment. For example, ΔW _failure = 0.1 may be used. Of course, ΔW _failure ≠ ΔW _success may be satisfied.

In step S828, the data frame processing unit 110 stores the LD value acquired in step S817 (or later-described step S829) as “LD failed in transfer” in a work area such as the DRAM 204 in FIG. For example, the data frame processing unit 110 initializes the linear list on the DRAM 204 to be empty in step S817, and holds the LD value acquired in step S817 (or step S829 described later) each time step S828 is executed. May be added to the linear list. Of course, other data structures such as an array may be used for storing “LD failed to transfer”.

Further, in step S828, the data frame processing unit 110 sets the current time as the last update time in the entry of the weighting table 104-i having the LD value acquired in step S817 (or step S829 described later) as the LD. Then, the process proceeds to step S829.

In step S829, the data frame processing unit 110 searches for other selectable adjacent node devices that have not been tried as LDs so far. Specifically, the data frame processing unit 110, in the weighting table 104-i corresponding to the GD value of the received data frame, is the smallest among the LDs other than the LD that failed to transfer and different from the OLS. The LD value associated with the weight is acquired. Note that the LD that failed to be transferred is stored in a work area such as the DRAM 204 in FIG. 4 in step S828, for example, in the form of a linear list.

That is, the data frame processing unit 110 selects the entry having the smallest weight value from the entries having the values (H1) and (H2) as LDs in the weighting table 104-i. Then, the data frame processing unit 110 stores the LD and weight values of the selected entry in a storage area such as the DRAM 204 in FIG.

(H1) A value different from the LD value acquired in the previous step S817 or S829 (H2) A value different from the OLS value stored in the step S808 or S810 Therefore, for example, updated to 0.2 in step S828 The adjacent node device associated with the weight is not selected as an LD in step S829, and an adjacent node device having a weight such as 0.8, which is greater than 0.2, may be selected in step S829.

Specific examples of the above steps S817 to S829 are as follows. For example, node devices N ₃ , N ₅ , and N ₇ are adjacent to the node device N ₄ in FIG. Then, as shown in Figure 12, the value of the OLS of FID management table _{105-N 4} entries E4 node device _{N 4} is _{N 3.}

In the example of FIG. 6, since the data frame processing unit 110-N ₄ of the node device N ₄ first acquires the LD value N ₇ in step S817, the data frame to the node device N ₇ as in step S104. Transmission is performed. However, since the transmission in step S104 fails as shown in FIG. 6, the data frame processing unit 110-N ₄ determines “transmission failure” in step S826.

Then, when the data frame processing unit 110-N ₄ executes step S829, the LD value other than the LD that failed to transfer (ie, N ₇ ) and different from the OLS (ie, N ₃ ) is only N _5. It is. Therefore, the value _{N 5} of the LD in step S829 is acquired.

When the LD value is acquired in step S829, the process returns from step S829 to step S818. Therefore, in the above example of the node device _{N 4,} after step S829, it is executed steps S818 ~ S826 again. Then, as shown in FIG. 6 as step S105, it is determined that transmission is successful in step S826, step S827 is executed, and the data frame reception process ends.

In addition, it will be as follows if the influence of updating a weight like Formula (7), for example with a specific example is demonstrated at step S828.
For example, in the network 2 of FIG. 2, it is assumed that the node device N ₁₀₆ receives a first data frame specifying the node device N ₁₁₈ as GD from the adjacent node device N ₁₀₈ at time T _rcv1 . Then, it is assumed that the weighting table 104-g ₁₀₆ -N ₁₀₆ corresponding to the node device N _{118 exists} in the node device N ₁₀₆ at time T _rcv1 . In the weighting table _{104-g 106 -N} 106 time _{T Rcv1,} the node device weight 0.4 to _{N 102} is, weight 0.7 to the node device _{N 103} is the weight 0 to the node device _{N 107} .1, is assumed that the weight 0.5 is associated with the node apparatus N ₁₀₈ , respectively.

Then, in step S817, the node device N ₁₀₇ associated with the minimum weight 0.1 is selected as the LD. However, when the data frame is transmitted at step S819, chance, for reasons such as shield between the node device _{N 106} and _{N 107} are placed, temporarily, the wireless link of the node device _{N 106} and _{N 107} Suppose that communication is lost.

Then, since no ACK frame is returned, the weight of the node device N ₁₀₇ is updated from 0.1 to 0.2 in step S828. In step S829, the node device N ₁₀₂ associated with the weight 0.4 is selected as the LD. Here, the transmission of the data frame is successful in step S819, the ACK frame from the node device _{N 102} is returned. Then, the weight of the node device _{N 102} in step S827 is updated from 0.4 to 0.3, the data frame reception process ends.

Here, it is assumed that the first data frame transmitted from the node device N ₁₀₆ to the node device N ₁₀₂ reaches the node device N ₁₁₈ without backtracking to the node device N ₁₀₆ . That is, in the weighting table 104-g ₁₀₆ -N ₁₀₆ , it is assumed that there is no entry whose weight is updated to 1 with the transfer of the first data frame.

Then, when the node device N _{106 receives} a second data frame from the node device N ₁₀₃ at this time T _rcv2 , which similarly designates the node device N ₁₁₈ as GD, the weighting table 104-g ₁₀₆ -N. The contents of ₁₀₆ are as follows. That is, node device N ₁₀₂ has weight 0.3, node device N ₁₀₃ has weight 0.7, node device N ₁₀₇ has weight 0.2, node device N ₁₀₈ has weight 0.5, Each is associated.

Therefore, in step S817, the node device N ₁₀₇ still associated with the minimum weight is selected as the LD even though the transfer of the first data frame has failed. If the communication quality of the radio link between the node devices N ₁₀₆ and N ₁₀₇ is improved at time T _rcv2 and the transmission of the second data frame in step S819 is successful, the node device N in step S827. The weight of ₁₀₇ returns to 0.1 again.

Here, _assuming that no backtracking occurs as a result of the transfer of the second data frame to the node device N ₁₀₇ , the weight of the node device N ₁₀₇ remains 0.1. Therefore, when the node device N ₁₀₆ receives a third data frame that similarly designates the node device N ₁₁₈ as GD from the adjacent node device other than the node device N _{107 at the} subsequent time T _rcv3 , the highest priority is given to the LD. The node device N ₁₀₇ is still selected.

As described above, if the weight is not set to the maximum value abruptly in step S829 but is slightly increased, the weighting table 104 does not react excessively to changes in the communication environment. Therefore, while the node device N ₁₀₆ receives a plurality of data frames designating the same node device as the GD one after another, if the link in which the failure has occurred temporarily recovers from the failure, the environment will be improved. Thus, the past learning result is again utilized for the selection of the LD. In other words, in the above example, the node device N ₁₀₇ that has been learned in the past when it is appropriate as the LD is again preferentially selected as the LD.

Alternatively, there may be a case where the radio link between the node devices N ₁₀₆ and N ₁₀₇ has not recovered from the failure at the time T _rcv2 . In this case, the node device N ₁₀₇ having a weight of 0.2 is selected as the LD at the time of transmitting the second data frame. However, since the ACK frame is not received, the weight of the node device N ₁₀₇ is 0.3. Updated to Finally, the node device N ₁₀₂ associated with the weight 0.3 may be selected as the LD, the transmission may be successful, and the weight may be updated to 0 and 2.

Then, at the time T _rcv3 , for example, when the node device N ₁₀₆ receives the third data frame from the node device N ₁₀₃ , the node device N ₁₀₂ associated with the weight 0.2 is selected as the LD, and transmission is performed. Successful, node device N ₁₀₂ may have a weight of 0.1. Then, for a while, the node device N ₁₀₆ may continue to select the node device N ₁₀₂ as the LD of the data frame designating the node device N ₁₁₈ as GD.

However, after that, if a failure occurs in the radio link between the node equipments N ₁₀₆ and N _102, an ACK frame is not returned from the node equipment N ₁₀₂ . In step S829, the LD is reselected.

In that case, the node device N ₁₀₇ that has been learned to be suitable as the LD before the time T _rcv1 is associated with the weights 0.5 and 0.7 and is relatively unsuitable as the LD. than ₁₀₈ and _{N 103,} are preferentially selected as LD. The reason is that learning of the weights at the time of transmission of the first and second data frames changes the weights gently as shown in step S828, and the weight of the node device N ₁₀₇ is still the node device N _108. This is because less than the weight of the or _{N 103.}

At this time, if the wireless link between the node devices N ₁₀₆ and N ₁₀₇ is recovered from the failure, the weight is again reduced to 0.2 for the node device N ₁₀₇ . In this way, even if it takes some time for recovery, the temporary environment change is not reflected excessively in the weighting table 104, so that past learning results are gradually reflected. Therefore, the probability that an appropriate LD is selected increases.

As described above, the weight is slightly adjusted in step S828 so as not to be excessively affected by the temporary failure.
Note that the procedure shown in FIG. 32 may be replaced with the procedure shown in FIG. The procedure shown in FIG. 33 is realized by replacing steps S822 and S824 shown in FIG. 32 with steps S822a and S824a, respectively.

33 is applied to a configuration in which the FID management table 105 does not manage entry times, for example. In such a configuration, the data frame processing unit 110 records the current time in the last update time field in step S824a. Further, the data frame processing unit 110 does not update the final time field in step S822a. According to this procedure, the “last update time” represents the time when the data frame is first transmitted to the adjacent node device. That is, in this case, the “last update time” corresponds to the entry time shown in FIG. Then, the data frame processing unit 110 can use the last update time in determining whether to transmit a normal data frame or an empty data frame in the backtrack operation.

According to the above configuration, the amount of memory consumed to realize the FID management table 105 is reduced. However, in this configuration, the timing at which each entry in the FID management table 105 is deleted by aging may be earlier than when the procedure shown in FIG. 32 is executed.

Returning to the description of the branch in step S818. If it is determined in step S818 that one of the two conditions (F1) and (F2) is satisfied, there is no longer an adjacent node device that can be selected as an LD, and the process proceeds to step S830 in FIG. That is, the backtrack operation is executed.

In steps S830 to S831, the data frame processing unit 110 searches the FID management table 105 using the FID and GS values of the received data frame as search keys. Then, the data frame processing unit 110 determines whether or not the corresponding entry is hit as a result of the search. If the corresponding entry is hit, the process proceeds to step S832, and if the corresponding entry is not hit, the process proceeds to step S849. Hereinafter, the entry retrieved from the FID management table 105 in step S830 may be referred to as a “target entry”.

If it is determined in step S807 that “an entry has been hit”, the entry found by the search in step S830 is the entry found by the search in step S806. If it is determined in step S807 that “the entry does not hit” and a new entry is created in step S823, the new entry created in step S823 is found by the search in step S830.

In step S831, “entry does not hit” is determined in the cases (I1) and (I2), in other words, in the cases (J1) and (J2).
(I1) In step S807, it is determined that “entry does not hit”.
(I2) Immediately after step S818 is executed for the first time, the process proceeds to step S830.

(J1) A data frame that has never been received by the node device 100 has been received.
(J2) In the weighting table 104-i corresponding to the GS value of the received data frame, the maximum value weight is associated with all the LDs.
In step S832, the data frame processing unit 110 initializes variables related to the backtrack operation. Specifically, in the FID management table 105, the number of empty data transmissions and the number of normal data transmissions of the entry specified by the FID / GD pair of the received frame are initialized to “zero”.

In steps S833 to S834, the data frame processing unit 110 checks whether the empty data transmission count of the target entry is within a predetermined upper limit count. The upper limit number of empty data transmission times is not particularly limited, but is “3”, for example. If the number of empty data transmissions is within the upper limit, the process proceeds to step S835. On the other hand, if the number of empty data transmissions exceeds the upper limit number, the process proceeds to step S840.

In step S835, the data frame processing unit 110 extracts the entry time TE from the corresponding entry in the FID management table 105. The entry time TE represents the time recorded in S824. That is, in this embodiment, the entry time TE represents the time when the node device first transferred the data frame received from the adjacent node device to another adjacent node device.

In steps S836 to S837, the data frame processing unit 110 determines whether the data frame received in step S201 is held in the OLS node apparatus. Specifically, “T-TE” and the holding time G of the buffer unit 109 are compared. “T” is the current time. TE is the entry time described above. That is, “T-TE” represents the elapsed time from the entry time to the current time. G represents a period during which a data frame is held in the buffer unit 109 in each node device, and is common to each node device.

When “T-TE” is shorter than the storage time G, it is determined that the data frame received in step S201 is held in the OLS node apparatus. In this case, the process proceeds to step S838. On the other hand, when “T-TE” is equal to or longer than the storage time G, it is determined that the data frame received in step S201 is not held in the OLS node apparatus. In this case, the process proceeds to step S840.

In step S838, the data frame processing unit 110 creates an empty data frame to be transmitted to the OLS node device and stores it in the transmission queue 114. At this time, the OLS recorded in the target entry of the FID management table 105 is set in the LD of this empty data frame. Further, only the data header of the data frame received in step S201 is stored in the payload of this empty data frame. Further, the data frame processing unit 110 writes the current time at the last update time of the target entry in the FID management table 105.

In step S839, the data frame processing unit 110 increments the number of empty data transmissions of the target entry in the FID management table 105. In this way, the data frame processing unit 110 creates an empty data frame and generates a transmission queue when the number of empty data transmissions is less than or equal to the upper limit number and the elapsed time from the entry time TE is shorter than the holding time G. Save to 114.

When the number of empty data transmission times exceeds the upper limit number, or when the elapsed time from the entry time TE is equal to or longer than the holding time G, the process of step S840 is executed. In step S840, the data frame processing unit 110 creates a normal data frame to be transmitted to the OLS node apparatus and stores it in the transmission queue 114. At this time, the OLS recorded in the target entry of the FID management table 105 is set in the LD of the normal data frame. Also, the payload of this normal data frame is the same as the payload of the data frame received in step S201. Further, the data frame processing unit 110 writes the current time at the last update time of the target entry in the FID management table 105.

In step S841, the data frame processing unit 110 increments the normal data transmission count of the target entry in the FID management table 105. Thus, the data frame processing unit 110 creates a normal data frame when the number of empty data transmission times exceeds the upper limit number, or when the elapsed time from the entry time TE is equal to or longer than the holding time G. Save in the transmission queue 114.

As a result, frames waiting for transmission (including normal data frames and empty data frames) are stored in the transmission queue 114. At this time, the data frame processing unit 110 executes the empty data frame aggregation processing shown in FIGS. 21 to 22, for example, periodically, independently of the data frame reception processing in step S205. Therefore, an aggregated empty data frame may be stored in the transmission queue 114.

The frames stored in the transmission queue 114 are periodically read out by the transmission unit 102 and transmitted. Alternatively, the transmission unit 102 may transmit a frame stored in the transmission queue 114 according to another trigger. However, the transmission unit 102 cannot access the transmission queue 114 during the period during which the empty data frame aggregation processing shown in FIGS.

The transmission unit 102 transmits the frame stored in the transmission queue 114 to the LD set in the ad hoc header of the frame. When the adjacent node device receives this frame, it returns an ACK frame.

The data frame processing unit 110 confirms the success or failure of frame transmission by the transmission unit 102 in steps S842 to S843. That is, the data frame processing unit 110 checks whether or not an ACK frame corresponding to the empty data frame created in step S838 or the normal data frame created in step S840 is received from the OLS node apparatus within a predetermined time. The “predetermined time” is sufficiently shorter than the holding time G of the buffer unit 109.

When receiving the ACK frame, the data frame processing unit 110 determines that the frame transmission is successful. In this case, the process proceeds to step S844. On the other hand, when the data frame processing unit 110 fails to receive the ACK frame within a predetermined time, the data frame processing unit 110 determines that the frame transmission has failed. In this case, the process proceeds to step S846.

In step S844, the data frame processing unit 110 reduces the weight corresponding to the pair of GD and LD values of the empty data frame created in step S838 or the normal data frame created in step S840 in the weighting table 104. In other words, the data frame processing unit 110 updates the weight corresponding to the LD of the transmitted data frame (that is, the OLS stored in step S808 or S810) in the weighting table 104-i corresponding to the GD of the received data frame. To do.

The details of step S844 are the same as step S827, and detailed description thereof is omitted. However, the data frame processing unit 110 may update the weight using, for example, equation (6). Further, the data frame processing unit 110 sets the current time as the last update time in the entry in which the weight is updated in the weighting table 104-i. Then, the data frame reception process ends.

If the transmission of the frame created in step S838 or S840 has failed (step S843: No), the processing in steps S846 and S847 is executed. That is, the data frame processing unit 110 checks whether the number of normal data transmissions of the target entry in the FID management table 105 is equal to or greater than a predetermined upper limit number. Here, the upper limit number of times of normal data transmission is not particularly limited, but is “3”, for example.

If the normal data transmission count of the target entry has reached the upper limit count, the data frame processing unit 110 deletes the data frame received in step S201 from the buffer unit 109 in step S848. In this case, the backtrack operation ends.

If the normal data transmission count of the target entry has not reached the upper limit count, the process returns to step S833. That is, if transmission of the frame created in step S838 or S840 fails, the processes in and after step S833 are executed again.

As described above, the node device according to the embodiment transmits an empty data frame to the OLS node device in the backtrack operation until the elapsed time from the entry time TE reaches the holding time G of the buffer unit 109. At this time, the transmission of the empty data frame is repeatedly executed until the upper limit number is reached. However, when it is detected that the empty data frame is received by the OLS node apparatus, the backtracking operation ends. The node device according to the embodiment performs the backtrack operation after the elapsed time from the entry time TE exceeds the holding time G of the buffer unit 109 or after the number of empty data frame transmissions reaches the upper limit number. The normal data frame is transmitted to the OLS node device. At this time, transmission of the normal data frame is repeatedly executed until the upper limit number is reached. However, when it is detected that the normal data frame is received by the OLS node apparatus, the backtrack operation is finished.

When there is no target entry in the FID management table 105 (step S831: No), the data frame processing unit 110 determines in step S849 that there is no OLS. That is, it is determined that the communication path forms a loop. In step S850, the data frame processing unit 110 deletes the data frame received in step S201 from the buffer unit 109. In this case, the backtrack operation ends.

Subsequently, with reference to FIG. 36, details of the weighting table adjustment processing in step S812a of FIG. 31 will be described. Note that the weighting table adjustment process in FIG. 36 is also called in step S1108a in FIG. In the description of FIG. 36, “hit weighting table 104-i” means a table hit in the search in step S811 in FIG. 31 or the search in step S1107 in FIG.

In step S861, the data frame processing unit 110 pays attention to the first entry of the adjacent node management table 103 (see FIG. 9). In the following description of FIG. 36, the entry in the adjacent node management table 103 focused on by the data frame processing unit 110 is referred to as a “target entry”.

Next, in step S862, the data frame processing unit 110 determines whether there is an entry including the value of the node ID of the entry of interest as LD in the hit weighting table 104-i. If there is an entry including the value of the node ID of the entry of interest as LD in the hit weighting table 104-i, the process proceeds to step S865. On the other hand, if there is no entry in the hit weighting table 104-i that includes the value of the node ID of the entry of interest as LD, the process proceeds to step S863.

In step S863, the data frame processing unit 110 adds a new entry to the hit weighting table 104-i. Subsequently, in step S864, the data frame processing unit 110 sets a value for the new entry added to the weighting table 104-i in step S863. That is, in the new entry, the data frame processing unit 110 sets the node ID value of the entry of interest in the adjacent node management table 103 as the LD field, the initial weight value as the weight field, and the current time as the last update time field. To do.

The initial weight value in step S864 is different from the initial weight value in step S308 in FIG. Specifically, the initial weight value in step S864 is the maximum value of weights less than 1 in the weight field of the hit weight table 104-i.

For example, if there are four entries in the weight field of the hit weighting table 104-i and the values of the respective weight fields are 0.4, 0.7, 1, and 0.5, the initial value in step S864 is set. The weighting value is 0.7. When the weight field value of the hit weighting table 104-i is 1 in all entries, the initial weighting value in step S864 is an arbitrary value less than 1, for example, in step S308 of FIG. 0.5 may be used similarly to the initial weighting value.

By using the initial weighting values as described above in step S864, the learning result reflected in the existing entries in the weighting table 104-i is preferentially considered. As a result, the route does not fluctuate more than necessary, in other words, the route becomes stable.

For example, in the above example where the values of the weight fields of the four entries are 0.4, 0.7, 1, and 0.5, respectively, the initial weighting value in step S864 is 0. 0 as in step S308 in FIG. Suppose that 5 is used. Then, an adjacent node device in which no weight has been learned (that is, an adjacent node device in which the node ID is recorded as an LD in the new entry added in step S863) is greater than an adjacent node device having a weight of 0.7. The LD is preferentially selected. That is, the weight 0.7 as the accumulated learning so far is ignored.

Therefore, in the first embodiment, it is possible to prevent an adjacent node device in which no weight has been learned from being selected as an LD preferentially over an adjacent node device in which a weight has already been learned, and prioritize learning results thus far. For the sake of consideration, the initial weight values defined above are used.

In step S865, the data frame processing unit 110 determines whether there are any entries that have not yet been noted in the adjacent node management table 103. If the data frame processing unit 110 has finished paying attention to all entries in the adjacent node management table 103, the processing in FIG. On the other hand, if an entry not yet noticed by the data frame processing unit 110 remains in the adjacent node management table 103, the process proceeds to step S866.

Then, in step S866, the data frame processing unit 110 pays attention to the next entry among the entries not yet noticed in the adjacent node management table 103. Then, the process returns to step S862.

The significance of the processing of FIG. 36 is as follows.
As a side effect of the aging process for each entry in the weighting table 104-i, there is a possibility of the following situation immediately before the process of FIG. That is, there is a possibility that an entry having the node ID of an adjacent node device registered in the adjacent node management table 103 as LD does not exist in the weighting table 104-i.

Here, the adjacent node device of the node device 100 is a potential candidate for the LD selected by the data frame processing unit 110 when transmitting the data frame. Therefore, it is desirable for proper operation of the node device 100 to cover all adjacent node devices in the LD field of the hit weighting table 104-i.

According to the weighting table adjustment process of FIG. 36 described above, the above-described situation that may occur as a side effect of the aging process is solved. That is, it is guaranteed that all node IDs registered in the adjacent node management table 103 are registered as LDs in the hit weighting table 104-i.

The data frame reception process in step S205 of FIG. 24 has been described in detail above with reference to FIGS. Next, processing related to notification of success or failure of transmission in steps S826 and S843 of the data frame reception processing will be described with reference to FIGS.

FIG. 37 is a flowchart of the ACK frame reception process in step S206 of FIG. The processing in FIG. 37 is started when an ACK frame is output from the frame branching processing unit 106 to the ACK processing unit 107.

In step S901, the ACK processing unit 107 determines whether the LD value of the ACK frame received from the frame branching processing unit 106 is equal to the own node ID. If the LD value of the ACK frame is equal to the own node ID, the process proceeds to step S902. If the LD value of the ACK frame is different from the own node ID, the process of FIG. The ACK processing unit 107 can also refer to its own node ID stored in advance in the flash memory 205, for example.

For example, when the node device N ₅ transmits an ACK frame for the data frame transmitted by the node device N _{4 in} step S105 of FIG. 6 as shown in FIG. 42 as step S105a, the irrelevant node device N ₃ also receives the ACK frame. To do. This is because the node device N ₃ is adjacent to the node device N ₅ .

However, since the ACK processing unit 107-N ₃ of the node device N ₃ immediately ends the process of FIG. 37 as a result of the determination in step S901, the node device N ₃ has a side effect due to the ACK frame unrelated to the node device N _3. Not receive.

In step S902, the ACK processing unit 107 specifies a transmitted data frame corresponding to the ACK frame from the GS and FID values of the ACK frame.
For example, in response to the data frame 303 in FIG. 7 transmitted from the node device N ₂ to the node device N ₃ in step S102 in FIG. 6, the node device N ₃ returns the ACK frame 322 in FIG. 7 to the node device N ₂ . Here, the ACK processor _{107-N 2} of the node device _{N 2} receives the response to the ACK frame 322 will be described in detail for the case of performing the process in FIG. 37, as follows.

In step S902, the ACK processing unit 107-N ₂ extracts GS and FID values (that is, N ₁ and F _a ) of the ACK frame 322. Further, since the buffer unit 109-N ₂ has the same format as that in FIG. 8, the buffer unit 109-N ₂ stores the data frame 303 that has been transmitted from the node device N ₂ . Therefore, the ACK processing unit 107-N ₂ searches the entry of the buffer unit 109-N _{2 using} the extracted GS and FID values (ie, N ₁ and F _a ) as keys, and identifies the entry including the data frame 303. To do.

In step S903, the ACK processing unit 107 notifies the data frame processing unit 110 of “successful transmission” regarding the transmitted data frame specified in step S902. Then, the process of FIG. 37 ends.

For example, the data frame processing unit 110 may be realized by the MPU 201 in FIG. 4 executing a program. In that case, the thread that causes the MPU 201 to function as the data frame processing unit 110 may sleep until the ACK frame is received after the data frame is transmitted. The notification of “successful transmission” in step S903 is a process for waking up a sleeping thread.

The notification in step S903 is accompanied by notification of the GS and FID values of the data frame specified in step S902. For example, in the above example, the ACK processing unit 107-N ₂ also notifies the data frame processing unit 110 of the GS and FID values (ie, N ₁ and F _a ) for identifying the data frame 303.

It should be noted that the data frame specified in step S902 is set in a state where it can be deleted from the buffer unit 109. However, in the buffer unit 109, the data frame is not in a state that can be immediately deleted when the corresponding ACK frame is received, but in a state in which the data frame can be deleted after the corresponding entry in the FID management table 105 is deleted. Is done. “Deletable” means a state in which overwriting with other data is allowed.

FIG. 38 is a flowchart showing processing when an ACK frame is not received before the timeout time. The processing in FIG. 38 is periodically performed, for example, triggered by an interrupt signal generated by the timer IC 203 in FIG. 4 at a predetermined interval.

In step S1001, the ACK processing unit 107 pays attention to the first entry of the buffer unit 109 (see FIG. 8). Hereinafter, in the description related to FIG. 38, the entry in the buffer unit 109 that is being watched by the ACK processing unit 107 is referred to as a “target entry”.

Subsequently, in step S1002, the ACK processing unit 107 compares the current time with the value of the timeout time field of the entry of interest. If the current time is after the timeout time, the process proceeds to step S1003. On the other hand, if the current time has not yet reached the timeout time, the process proceeds to step S1005.

In step S1003, the ACK processing unit 107 notifies the data frame processing unit 110 of “transmission failure” regarding the data frame stored in the entry of interest in the buffer unit 109. The notification in step S1003 may be, for example, a process for waking up a sleeping thread, for example, similarly to the notification in step S903 in FIG.

Similarly to the notification in step S903, the notification in step S1003 is also accompanied by notification of the GS and FID values of the data frame. Specifically, the ACK processing unit 107 reads the GS and FID values of the data frame stored in the entry of interest, identifies the data frame based on the read GS and FID values, and identifies “ “Transmission failure” is notified to the data frame processing unit 110.

In the case of transmission failure, the data frame processing unit 110 may select an adjacent node device that has not been tried as an LD as a new LD and try to retransmit the data frame. Accordingly, the entry of interest is not deleted from the buffer unit 109 at the time of step S1003.

Subsequently, in step S1004, the ACK processing unit 107 sets the time T _timeout of Expression (5) as the timeout time of the entry of interest. Then, the process proceeds to step S1005.

In step S1005, the ACK processing unit 107 determines whether or not an entry that has not been noticed still remains in the buffer unit 109. If the ACK processing unit 107 finishes paying attention to all entries in the buffer unit 109, the processing in FIG. On the other hand, if an entry not yet noticed by the ACK processing unit 107 remains in the buffer unit 109, the process proceeds to step S1006.

In step S1006, the ACK processing unit 107 pays attention to the next entry in the buffer unit 109 that has not been noticed yet. Then, the process returns to step S1002.
Incidentally, the data frame reception processing described with reference to FIGS. 30 to 35 is an example in the case where the node device 100 is a node device of a type that does not become a GS as described above. In the following, with reference to FIGS. 39 to 41, processing unique to a type of node device that can be a GS will be described.

FIG. 39 and FIG. 40 are flowcharts of the transmission process when the node device 100 becomes a GS and transmits a data frame. The processing in FIG. 39 is started when a request from the upper layer processing unit 111 to the data frame processing unit 110 is triggered.

In step S1101, the data frame processing unit 110 acquires the GD value and payload of the data frame from the upper layer processing unit 111 as a result of the upper layer protocol processing in the upper layer processing unit 111.

For example, the “upper layer protocol” may be an Ethernet protocol. In that case, the upper layer processing unit 111 outputs an Ethernet frame to the data frame processing unit 110 as a payload of the data frame defined in the first embodiment. Further, the upper layer processing unit 111 notifies the data frame processing unit 110 of the value set in the GD of the data frame in the first embodiment.

Then, the data frame processing unit 110 creates a new data frame including the payload acquired from the upper layer processing unit 111, and sets the value acquired from the upper layer processing unit 111 in the GD of the generated data frame. For example, in the example of FIG. 6, the data frame processing unit _{110-N 1} node device _{N 1} from the upper layer processing section _{111-N 1} to _{N 7} was obtained as the value of GD, and _{N 7} to the GD of the data frame Set.

Subsequently, in step S1102, the data frame processing unit 110 obtains the length of the payload acquired in step S1101, and sets it in the length field of the created data frame. For example, in the example of FIG. 6, as shown in data frames 302 and 303 in FIG. 7, since the length of the payload is _{P a,} the data frame processing unit _{110-N 1} node device _{N 1} was prepared It is set to P _a length field of the data frame.

In step S1103, the data frame processing unit 110 sets its own node ID in the GS and LS of the created data frame. For example, in the example of FIG. 6, the data frame processing unit 110-N ₁ of the node device N ₁ sets N ₁ to GS and LS of the created data frame.

In step S1104, the data frame processing unit 110 requests the FID generation unit 113 to generate a new FID. Then, since the FID generation unit 113 generates a new FID and outputs it to the data frame processing unit 110, the data frame processing unit 110 sets the generated FID in the FID field of the created data frame.

Furthermore, in step S1105, the data frame processing unit 110 sets a predetermined value D (see FIG. 7) indicating “data frame” in the type field of the created data frame. Note that the execution order of the above steps S1102 to S1105 is in no particular order.

When the creation of the data frame to be transmitted is completed as described above, the data frame processing unit 110 stores the created data frame in the buffer unit 109 in step S1106. In other words, the data frame processing unit 110 secures a new entry area in the buffer unit 109 and stores the created data frame in the secured area. As shown in FIG. 8, the buffer unit 109 has a timeout time field, but at this time, the timeout time is not set.

Subsequently, in step S1107, the data frame processing unit 110 searches the weighting table 104 using the value of GD designated by the upper layer processing unit 111 in step S1101.
In step S1108, the data frame processing unit 110 determines whether the weighting table corresponding to the designated GD value has been hit as a result of the search in step S1107. If the weighting table corresponding to the designated GD value hits, the process proceeds to step S1108a. If the weighting table corresponding to the designated GD value does not exist, the process proceeds to step S1009.

In step S1108a, the data frame processing unit 110 performs the weighting table adjustment process of FIG. 36 to neutralize the side effects of the aging process. Then, the process proceeds to step S1110.

In step S1109, the data frame processing unit 110 adds a new weighting table corresponding to the GD value designated in step S1101 to the weighting table 104. Specifically, in step S1109, the data frame processing unit 110 performs processing similar to steps S813 to S816 in FIG.

That is, in step S1109, the data frame processing unit 110 adds a new weighting table corresponding to the GD value designated by the upper layer processing unit 111, and the GD of the GD designated by the upper layer processing unit 111 in the new weighting table. Set the value as GD. Further, the data frame processing unit 110 creates the same number of new entries as the adjacent node management table 103 in the new weighting table. Then, the data frame processing unit 110 sets the node ID, the initial weight value, and the current time of each entry in the adjacent node management table 103 for each created entry.

In the following, for convenience of explanation, the weighting table corresponding to the value of GD designated in step S1101 is referred to by the reference numeral “104-i”. That is, the weighting table 104-i is a table that has been hit by the search in step S1107 or a table that has been added in step S1109.

As described above, after it is determined in step S1108 that the weighting table 104-i is hit or after the weighting table 104-i is created in step S1109, the process proceeds to step S1110.

In step S 1110, the data frame processing unit 110 acquires the LD value associated with the minimum weight in the weighting table 104-i corresponding to the GD value designated by the upper layer processing unit 111. As illustrated in FIG. 11, a plurality of entries in the weighting table 104-i may have the same minimum weight. In that case, the data frame processing unit 110 selects and acquires any one of a plurality of LD values associated with the minimum weight in step S1110. The data frame processing unit 110 stores the acquired LD value and the corresponding weight value in a storage area such as the DRAM 204 of FIG.

Subsequently, the process proceeds to step S1111 in FIG. 40. In step S1111, the data frame processing unit 110 determines whether one of the following two conditions (K1) and (K2) is satisfied.

(K1) The weight corresponding to the LD value acquired in step S1110 is the maximum weight value (specifically, 1.0 in the first embodiment).
(K2) Transmission to all LDs registered in the weighting table 104-i has failed.

If the condition (K1) or (K2) is satisfied, there is no longer any adjacent node device that can be selected as an LD, and the process moves to step S1112.
On the other hand, if neither of the conditions (K1) and (K2) is satisfied, there are still adjacent node devices that can be selected as the LD. In other words, there is at least one adjacent node device that does not correspond to any of (G1) to (G3) described for step S818 of the data frame reception process. Then, the node ID of the adjacent node device that can be selected as the LD is acquired in step S1110 (or step S1125 described later). Therefore, if it is determined in step S1111 that neither condition (K1) nor (K2) is satisfied, the process proceeds to step S1114.

If the condition (K1) or (K2) is satisfied, the data frame processing unit 110 discards the data frame in step S1112. That is, the data frame processing unit 110 deletes the entry newly created in step S1106 and storing the data frame from the buffer unit 109.

In step S1113, the data frame processing unit 110 notifies the upper layer processing unit 111 of “transmission failure”. That is, the data frame processing unit 110 notifies the upper layer processing unit 111 that the data frame has not been successfully transmitted to any adjacent node device. Then, the processes in FIGS. 39 to 40 are completed.

On the other hand, if it is determined in step S1111 that neither of the conditions (K1) and (K2) is satisfied, the process of attempting to transfer the data frame to the adjacent node device identified by the acquired LD value is performed in step S1111. This is performed in S1114 to S1125.

In step S1114, the data frame processing unit 110 sets the LD value acquired in step S1110 or step S1125 described later to the LD of the data frame stored in the buffer unit 109 in step S1106. Then, the data frame processing unit 110 requests the transmission unit 102 to transmit a data frame in which the LD value is set. Then, the transmission part 102 transmits a data frame.

Subsequently, in step S1115, the data frame processing unit 110 sets the time T _timeout of Expression (5) as the timeout time of the entry in the buffer unit 109 that stores the data frame in step S1106.

In step S1116, the data frame processing unit 110 searches the FID management table 105 using the own node ID and the FID generated by the FID generation unit 113 in step S1104.

Next, in step S1117, the data frame processing unit 110 determines whether an entry has been hit in the search of the FID management table 105 in step S1116. When step S1117 is executed for the first time, it is determined that “the entry has not been hit”, and when step S1117 is executed for the second time or later, it is determined that “the entry has been hit”.

If the entry is hit in the search in step S1116, the process proceeds to step S1118. On the other hand, if the entry is not hit in the search of step S1116, the process proceeds to step S1119.

In step S1118, the data frame processing unit 110 updates the entry hit in the search in step S1116. Specifically, the data frame processing unit 110 sets the LD value of the data frame transmitted in step S1114 in the LD field in the entry hit in the search in step S1116, and sets the current value in the last update time field. Set the time. Then, the process proceeds to step S1121.

In step S 1119, the data frame processing unit 110 adds a new entry to the FID management table 105. In step S1120, the data frame processing unit 110 sets a value for the new entry. Specifically, in the new entry, the data frame processing unit 110 copies the value of the data frame transmitted in step S1114 to each field of FID, GS, and LD. In addition, in the new entry, the data frame processing unit 110 sets the current time in the last update time field, and copies its own node ID in the OLS field.

For example, as shown in FIG. 12, the node FID management table _{105-N 1} entry E1 devices _{N 1} is for the data frame processing unit _{110-N 1} node device _{N 1} created by the above processing.

In step S1121, the data frame processing unit 110 waits for notification of the success or failure of transmission in step S1114. Details of step S1121 are the same as step S825 of FIG. When the data frame processing unit 110 receives a notification of “transmission success” or “transmission failure” from the ACK processing unit 107 after waiting in step S1121, the process proceeds to step S1122.

In step S1122, the data frame processing unit 110 determines whether or not the transmission in step S1114 is successful based on the notification received from the ACK processing unit 107. If the transmission is successful, the process proceeds to step S1123. If the transmission fails, the process proceeds to step S1124.

If the transmission is successful, in step S1123, the data frame processing unit 110 decreases the weight corresponding to the combination of GD and LD of the data frame transmitted in step S1114 in the weighting table 104.

That is, the data frame processing unit 110 uses the weight corresponding to the LD of the transmitted data frame in the weighting table 104-i corresponding to the value of GD designated from the higher layer processing unit 111, for example, using Equation (6). Update. Further, the data frame processing unit 110 sets the current time as the last update time in the entry whose weight is updated in the weighting table 104-i. Then, the processes in FIGS. 39 to 40 are finished.

Conversely, if the transmission fails, in step S1124, the data frame processing unit 110 increases the weight corresponding to the combination of GD and LD of the data frame transmitted in step S1114 in the weighting table 104.

In other words, the data frame processing unit 110 uses the weight corresponding to the LD of the transmitted data frame in the weighting table 104-i corresponding to the GD value designated by the upper layer processing unit 111, for example, using Equation (7). Update.

In step S 1124, the data frame processing unit 110 further stores the LD value of the transmitted data frame as “LD failed in transmission” in a work area such as the DRAM 204 in FIG. Similarly to step S828 in FIG. 32, a data structure such as a linear list or an array may be used for storing “LD failed to transmit”.

Further, in step S1124, the data frame processing unit 110 further sets the current time as the last update time in the entry whose weight is updated in the weighting table 104-i. Then, the process proceeds to step S1125.

In step S1125, the data frame processing unit 110 searches for other selectable adjacent node devices that have not been tried as LDs so far. Specifically, the data frame processing unit 110 uses the minimum weight among the LDs other than the LD that failed to transmit in the weighting table 104-i corresponding to the GD value designated by the higher layer processing unit 111. The associated LD value is acquired. Here, the LDs that failed to be transmitted are stored in a work area such as the DRAM 204 of FIG. 4 in step S1124, for example, in the form of a linear list or an array.

That is, the data frame processing unit 110 acquires, in the weighting table 104-i, an LD value that has not been acquired in step S1110 or S1125 in the past and that is associated with the minimum weight. The data frame processing unit 110 stores the acquired LD value and the corresponding weight value in a storage area such as the DRAM 204 of FIG. Then, the process returns to step S1111.

FIG. 41 is a flowchart of a process performed by the node device 100 that can be a GS instead of the processes of FIGS. 34 to 35 as part of the data frame reception process.
When the node device 100 is a node device that can also be a GS, steps S801 to S829 in the data frame reception process are the same as those in the case where the node device 100 does not become a GS, as shown in FIGS. 30 to 32. is there. However, if the node device 100 is a node device that can also be a GS, if the data frame processing unit 110 determines that “one of the conditions (F1) and (F2) is satisfied” in step S818 in FIG. Shifts to step S871 of FIG.

In step S871, the data frame processing unit 110 determines whether or not the GS value of the received data frame is its own node ID. If the GS value of the received data frame matches the own node ID, the process proceeds to step S872. On the other hand, if the GS value of the received data frame is different from the own node ID, the process proceeds to step S874. Note that step S874 is a backtrack operation by the frame transmission method of the embodiment, and is basically the same as steps S830 to S850 shown in FIGS. Therefore, the process of step S874 is omitted.

In step S872, the data frame processing unit 110 notifies the upper layer processing unit 111 of “transmission failure”. For the notification, the data frame processing unit 110 may extract a payload from the received data frame, for example, and output the payload or a part of the payload to the upper layer processing unit 111. Then, the upper layer processing unit 111 can recognize which data has failed to be transmitted based on the content of the payload received from the data frame processing unit 110.

In step S873, the data frame processing unit 110 discards the received data frame. That is, the data frame processing unit 110 deletes the entry found in step S801 from the buffer unit 109. Note that step S873 is executed in the following (L1) or (L2).

(L1) The data frame transmitted by the node device 100 itself as GS is returned to the node device 100 by the backtrack and received, and all the adjacent node devices of the node device 100 are (L1-1) or (L1-2).

(L1-1) Corresponds to the weight of the maximum value.
(L1-2) If a data frame is transmitted by designating as LD, transmission fails.
(L2) The GS of the received data frame is a node device other than the node device 100, and all adjacent node devices other than the OLS are (L2-1) or (L2-2), and Transmission of the data frame to the OLS failed.
(L2-1) Corresponds to the maximum value weight.
(L2-2) When a data frame is transmitted by designating as LD, transmission fails.

FIG. 42 is a timing chart showing the recognition of adjacent nodes by the transmission / reception of a hello frame and the route selection of FIG.

In the network 1 of FIG. 1, each of the node devices N ₁ to N ₇ independently performs the hello frame transmission process of FIG. Which node is device is arbitrary to send a hello frame to the above, in the example of FIG. 42, first, the node device N ₂ executes the step S403 of FIG. 26 in step S1201, transmits a hello frame. Then, the hello frame is received by the node devices N ₁ , N ₃ , and N ₆ adjacent to the node device N ₂ , respectively. Then, each of the node devices N ₁ , N ₃ , and N ₆ calls and executes the hello frame reception process of FIG. 25 in step S203 of FIG. 24, and recognizes the node device N ₂ as an adjacent node device.

In the example of FIG. 42, followed by step S1202, the node device _{N 4} executes the step S403 in FIG. 26, and transmits the hello frame. Then, the hello frame is received by the node devices N ₃ , N ₅ , and N ₇ adjacent to the node device N ₄ , respectively. Then, each of the node devices N ₃ , N ₅ , and N ₇ calls and executes the hello frame reception process of FIG. 25 in step S203 of FIG. 24, and recognizes the node device N ₄ as an adjacent node device.

Further, in step S1203, the node device _{N 3} executes step S403 in FIG. 26, and transmits a hello frame 312 of FIG. Then, the hello frame 312 are respectively received by the node device _N 2, _{N 4,} and _{N 5} adjacent to the node device _{N 3.} Then, each of the node devices N ₂ , N ₄ , and N ₅ calls and executes the hello frame reception process of FIG. 25 in step S203 of FIG. 24, and recognizes the node device N ₃ as an adjacent node device.

In step S1204, the node device _{N 7} executes the step S403 in FIG. 26, and transmits the hello frame. In the time of step S1204, the link between the node device N ₄ and N ₇ is that a fault has not occurred yet. Therefore, the hello frame is received by the node devices N ₄ and N ₆ adjacent to the node device N ₇ , respectively. Then, each of the node devices N ₄ and N ₆ calls and executes the hello frame reception process of FIG. 25 in step S203 of FIG. 24, and recognizes the node device N ₇ as an adjacent node device.

In step S1205, the node device _{N 1} executes the step S403 in FIG. 26, and transmits the hello frame. Then, the hello frame is received by the node device N ₂ adjacent to the node device N ₁ . Then, the node device N ₂ executes call the hello frame reception process in FIG. 25 in step S203 of FIG. 24, it recognizes the node device N ₁ as an adjacent node device.

Further, in step S1206, the node device _{N 6} executes the step S403 in FIG. 26, and transmits the hello frame. Then, the hello frame is received by the node devices N ₂ and N ₇ adjacent to the node device N ₆ , respectively. Then, the node devices N ₂ and N ₇ call and execute the hello frame reception process of FIG. 25 in step S203 of FIG. 24, respectively, and recognize the node device N ₆ as an adjacent node device.

In step S1207, the node device _{N 5} executes the step S403 in FIG. 26, and transmits the hello frame. Then, the hello frame is received by the node devices N ₃ and N ₄ adjacent to the node device N ₅ , respectively. Then, the node devices N ₃ and N ₄ call and execute the hello frame reception process of FIG. 25 in step S203 of FIG. 24, respectively, and recognize the node device N ₅ as an adjacent node device.

Through the above steps S1201 to S1207, the node devices N ₁ to N ₇ in the network 1 shown in FIGS. 1 and 6 recognize the adjacent node devices, respectively, and store the adjacent node management tables 103-N ₁ to 103-N _{7 respectively} . Update. Further, as shown in FIG. 25, the node devices N ₁ to N ₇ may update the weighting tables 104-N ₁ to 104-N ₇ ) in response to the reception of the hello frame.

Then, it is assumed that a failure occurs in the link between the node device _{N 4} and _{N 7} in step S1208. Further, regardless of the occurrence of the fault, the node device N ₁ in step S101, the data frame specifying a node device N ₇ as GD, and transmits the specified node device N ₂ as LD. In other words, the node device _{N 1} in step S101, performs the frame transmission processing shown in FIGS. 39 to 40.

Then, the node device N ₂ that has received the data frame calls and executes the processes of FIGS. 30 to 35 from step S 205 of FIG. The node device _{N 2} at step S803 of FIG. 30 transmits the ACK frame, is represented as step S101a in FIG. 42.

On the other hand, the node device _{N 1} is waiting to receive an ACK frame at step S1121 in FIG. 40. When the node device N ₁ receives the ACK frame transmitted in step S101a, the node device N ₁ calls and executes the processing of FIG. 37 from step S206 of FIG. 24. As a result, the standby of step S1121 ends, and steps S1122 and S1123 To finish the process of FIG.

Also, the node device _{N 2} that transmitted the ACK frame in step S803 of FIG. 30, as shown in step S101a, the step S804 to continue the subsequent processing, at step S819 of FIG. 32, specifies the node device _{N 3} as LD Send a data frame. The transmission in step S819 corresponds to step S102 in FIG. FIG. 7 illustrates the data frame 303 transmitted in step S102.

Then, the node device N ₃ that has received the data frame calls and executes the processes of FIGS. 30 to 35 from step S 205 of FIG. The node device _{N 3} in step S803 in FIG. 30 transmits the ACK frame, is represented as step S102a in FIG. 42. FIG. 7 illustrates the ACK frame 322 transmitted in step S102a.

On the other hand, the node device _{N 2} is waiting to receive an ACK frame at step S825 in FIG. 32. When the node device N ₂ receives the ACK frame transmitted in step S102a, the node device N ₂ calls and executes the processing in FIG. 37 from step S206 in FIG. 24. As a result, the node device N ₂ finishes waiting in step S825, and steps S826 and S827. To finish the process of FIG.

Also, the node device _{N 3} that transmitted the ACK frame in step S803 of FIG. 30, as shown in step S102a, the step S804 to continue the subsequent processing, at step S819 of FIG. 32, specifies the node device _{N 4} as LD Send a data frame. The transmission in step S819 corresponds to step S103 in FIG. FIG. 7 illustrates the data frame 304 transmitted in step S103.

Then, the node device N ₄ that has received the data frame calls and executes the processes of FIGS. 30 to 35 from step S 205 of FIG. The node device _{N 4} in step S803 of FIG. 30 transmits the ACK frame, is represented as step S103a in FIG. 42.

On the other hand, the node device _{N 3} is waiting to receive an ACK frame at step S825 in FIG. 32. When the node device N ₃ receives the ACK frame transmitted in step S103a, the node device N ₃ calls and executes the processing in FIG. 37 from step S206 in FIG. 24. As a result, the node device N ₃ finishes waiting in step S825, and steps S826 and S827. To finish the process of FIG.

Further, as shown in step S103a, the node device N _{4 that} has transmitted the ACK frame in step S803 in FIG. 30 continues the processing from step S804, and specifies the node device N ₇ as the LD in step S819 in FIG. Send a data frame. The transmission in step S819 corresponds to step S104 in FIG.

However, the link between the node device N ₄ and N ₇ in step S1208 is failure, the data frame does not reach the node device N _7. Therefore, in FIG. 42, the arrow in step S104 is a broken line from the middle.

Node device _{N 4} is waiting to receive an ACK frame at step S825 in FIG. 32. However, since the ACK frame is not received from the node device N ₇ , the node device N ₄ determines that transmission of the data frame to the node device N ₇ has failed in step S1003 of the processing of FIG. 38 that is periodically executed. recognize.

As a result, the node device _{N 4} is finished standby step S825, step S826, S828, S829, executes the processing of S818 in this order. Then, the node device _{N 4} is in the following step S819, transmits the data frame by specifying a node device _{N 5} as LD. The transmission in step S819 corresponds to step S105 in FIG.

Then, the node device N ₅ that has received the data frame calls and executes the processing of FIGS. 30 to 35 from step S205 of FIG. The node device _{N 5} in step S803 of FIG. 30 transmits the ACK frame, is represented as step S105a in FIG. 42.

On the other hand, the node device _{N 4} is waiting to receive an ACK frame at step S825 in FIG. 32. When the node device N ₄ receives the ACK frame transmitted in step S105a, the node device N ₄ calls and executes the processing in FIG. 37 from step S206 in FIG. 24. As a result, the node device N ₄ finishes waiting in step S825, and steps S826 and S827. To finish the process of FIG.

Also, ACK frame node has transmitted the device _{N 5} in step S803 of FIG. 30, as shown in step S105a, step S804 to continue the subsequent processing, at step S819 of FIG. 32, specifies the node device _{N 3} as LD Send a data frame. The transmission in step S819 corresponds to step S106 in FIG.

Then, the node device N ₃ that has received the data frame calls and executes the processes of FIGS. 30 to 35 from step S 205 of FIG. The node device _{N 3} in step S803 in FIG. 30 transmits the ACK frame, is represented as step S106a in FIG. 42.

On the other hand, the node device _{N 5} is waiting to receive an ACK frame at step S825 in FIG. 32. Then, the node device _{N 5} receives the ACK frame transmitted in step S 106 a, invokes and executes the processing of FIG. 37 from step S206 in FIG. 24, as a result, after a wait in step S825, and step S826 S827 To finish the process of FIG.

Also, the node device _{N 3} that transmitted the ACK frame in step S803 of FIG. 30, as shown in step S106a, the step S804 to continue the subsequent processing, at step S819 of FIG. 32, specifies the node device _{N 5} as LD Send a data frame. The transmission in step S819 corresponds to step S107 in FIG.

Then, the node device N ₅ that has received the data frame calls and executes the processing of FIGS. 30 to 35 from step S205 of FIG. The node device _{N 5} in step S803 of FIG. 30 transmits the ACK frame, is represented as step S107a in FIG. 42.

On the other hand, the node device _{N 3} is waiting to receive an ACK frame at step S825 in FIG. 32. When the node device N ₃ receives the ACK frame transmitted in step S107a, the node device N ₃ calls and executes the processing in FIG. 37 from step S206 in FIG. 24. As a result, the node device N ₃ finishes waiting in step S825, and steps S826 and S827. To finish the process of FIG.

Also, the node device _{N 5} that has transmitted an ACK frame in step S803 of FIG. 30, as shown in step S107a continues the step S804 and subsequent steps. Specifically, the process proceeds to step S830 of FIG. 34 from step S818 in FIG. 32, the node device _{N 5} transmits a data frame by specifying a node device _{N 4} is OLS as LD. This frame transmission corresponds to step S108 in FIG. At this time, when the data frame to the node device N ₄ is expected to be conserved, the node device N ₅ transmits an empty data frame instead of the normal data frames. Thus, the node device N ₅ is the backtracking operation, transmits the normal data frames or null data frame to the node apparatus N _4.

Then, the node device N ₄ that has received the data frame calls and executes the processes of FIGS. 30 to 35 from step S 205 of FIG. At this time, when receiving an empty data frame, the node device N ₄ extracts the corresponding data frame from the buffer unit 109. The node device _{N 4} in step S803 of FIG. 30 transmits the ACK frame, is represented as step S108a in FIG. 42.

On the other hand, the node device _{N 5} is waiting to receive an ACK frame at step S842 in FIG. 35. Then, the node device _{N 5} receives the ACK frame transmitted in step S108a, invokes and executes the processing of FIG. 37 from step S206 in FIG. 24, as a result, after a wait in step S842, executes Step S844 Then, the processing in FIGS. 34 to 35 is completed.

Also, the node device _{N 4} which has transmitted the ACK frame in step S803 of FIG. 30, as shown in step S108a continues the step S804 and subsequent steps. Specifically, the process proceeds to step S830 of FIG. 34 from step S818 in FIG. 32, the node apparatus _{N 4} transmits the data frame by specifying a node device _{N 3} is OLS as LD. This frame transmission corresponds to step S109 in FIG. At this time, when it is expected that the data frame is stored in the node device N ₃ , the node device N ₄ transmits an empty data frame instead of the normal data frame. Thus, the node device N ₄ transmits a normal data frame or an empty data frame to the node device N ₃ by the backtrack operation.

Then, the node device N ₃ that has received the data frame calls and executes the processes of FIGS. 30 to 35 from step S 205 of FIG. At this time, when receiving an empty data frame, the node device N ₃ extracts the corresponding data frame from the buffer unit 109. The node device _{N 3} in step S803 in FIG. 30 transmits the ACK frame, is represented as step S109a in FIG. 42.

On the other hand, the node device _{N 4} is waiting to receive an ACK frame at step S842 in FIG. 35. When the node device N ₄ receives the ACK frame transmitted in step S109a, the node device N ₄ invokes and executes the processing in FIG. 37 from step S206 in FIG. 24. As a result, the node device N ₄ finishes waiting in step S842 and executes step S844. Then, the processing in FIGS. 34 to 35 is completed.

Also, the node device _{N 3} that transmitted the ACK frame in step S803 of FIG. 30, as shown in step S109a continues the step S804 and subsequent steps. Specifically, the process proceeds to step S830 of FIG. 34 from step S818 in FIG. 32, the node device _{N 3} transmits a data frame by specifying a node device _{N 2} is OLS as LD. This frame transmission corresponds to step S110 in FIG. At this time, when the data frame to the node device N ₂ is expected to be conserved, the node device N ₃ transmits an empty data frame instead of the normal data frames. Thus, the node device N ₃ is the backtracking operation, transmits the normal data frames or null data frame to the node apparatus N _2.

Then, the node device N ₂ that has received the data frame calls and executes the processes of FIGS. 30 to 35 from step S 205 of FIG. At this time, when receiving the empty data frame, the node device N ₂ extracts the corresponding data frame from the buffer unit 109. The node device _{N 2} at step S803 of FIG. 30 transmits the ACK frame, is represented as step S110a in FIG. 42.

On the other hand, the node device _{N 3} is waiting to receive an ACK frame at step S842 in FIG. 35. Then, the node device _{N 3} receives the ACK frame transmitted in step S110a, invokes and executes the processing of FIG. 37 from step S206 in FIG. 24, as a result, after a wait in step S842, executes Step S844 Then, the processing in FIGS. 34 to 35 is completed.

Also, the node device _{N 2} that transmitted the ACK frame in step S803 of FIG. 30, as shown in step S110a, the step S804 to continue the subsequent processing, at step S819 of FIG. 32, specifies the node device _{N 6} as LD Send a data frame. The transmission in step S819 corresponds to step S111 in FIG.

Then, the node device N ₆ that has received the data frame calls and executes the processing of FIGS. 30 to 35 from step S205 of FIG. Node device _{N 6} at step S803 of FIG. 30 that transmits the ACK frame, and is represented as step S111a in FIG. 42.

On the other hand, the node device _{N 2} is waiting to receive an ACK frame at step S825 in FIG. 32. When the node device N ₂ receives the ACK frame transmitted in step S111a, the node device N ₂ calls and executes the processing in FIG. 37 from step S206 in FIG. 24. As a result, the node device N ₂ finishes waiting in step S825, and steps S826 and S827. To finish the process of FIG.

Further, as shown in step S111a, the node device N _{6 that} has transmitted the ACK frame in step S803 in FIG. 30 continues the processing from step S804, and specifies the node device N ₇ as the LD in step S819 in FIG. Send a data frame. The transmission in step S819 corresponds to step S112 in FIG.

Then, the node device N ₇ that has received the data frame calls and executes the processing of FIGS. 30 to 35 from step S205 of FIG. Node device _{N 7} in the step S803 of FIG. 30 that transmits the ACK frame, and is represented as step S112a in FIG. 42.

Through the series of processes described above, in the entire network 1, even if a failure occurs in step S1208, as a result of the autonomous distributed cooperation of the node devices N ₁ to N ₇ , the route <N ₁ , N ₂ , N ₆ , N ₇ > is selected and learned. That is, the weighting tables 104-N ₁ to 104-N ₆ are updated in the node devices N ₁ to N ₆ by the series of processes described above.

Thus, after step S112a, as a result of learning, the node device N ₇ data frame specified as GD, instead of being trial and error transfer while backtracking in the network 1 as shown in FIG. 6, initially Is transferred efficiently.

Next, the second embodiment will be described. In the second embodiment, the node devices are wired.
In the first embodiment, the reception unit 101 and the transmission unit 102 in FIG. 3 are realized by the wireless module 206 in FIG. 4, and the node devices are connected by a wireless link. That is, the first embodiment assumes a wireless ad hoc network. On the other hand, in the second embodiment, for example, the node devices of the network shown in FIG. 1 or FIG. 2 are connected by a wired link. That is, the second embodiment assumes a wired ad hoc network. A specific example of the second embodiment will be described below with reference to FIGS. 43 to 44. FIG.

FIG. 43 is a diagram illustrating an example of a wired network to which the second embodiment is applied. The network 4 in FIG. 43 includes a plurality of node devices 100a to 100i and is an example of a wired ad hoc network. First, an outline of the configuration of the node device 100a will be described.

The configuration of the node devices 100a to 100i is the same. Components that are similar to each other may be assigned the same reference numerals except for subscripts, such as “211a-1”, “211a-2”, “211b-1”, and the detailed description thereof may be omitted.

The node devices 100a to 100i are realized by physical ports (hereinafter simply referred to as “ports”) for wired communication and PHY chips instead of the reception unit 101 and the transmission unit 102 of FIG. A reception unit and a transmission unit (not shown) are included. In the example of FIG. 43, the node device 100a includes four ports 211a-1 to 211a-4, but the number of ports is arbitrary according to the embodiment.

Note that the ports 211a-1 to 211a-4 are ports for performing frame communication according to the second embodiment. That is, the same data frame as in the first embodiment shown in FIG. 7 is transmitted / received via the ports 211a-1 to 211a-4. In other words, the ports 211a-1 to 211a-4 are ports for the node device 100a to make a wired connection with the adjacent node device.

Hereinafter, for convenience of explanation, it is assumed that there is one PHY chip corresponding to one port. However, physically, one PHY chip can perform input / output processing of a plurality of ports.

In the second embodiment, neither an ACK frame nor a hello frame is used. Therefore, the node device 100a does not include the ACK processing unit 107 and the hello frame generation unit 112 in FIG. In the second embodiment, some of the operations of the frame branch processing unit 106, the link management unit 108, and the data frame processing unit 110 are different from those in the first embodiment. Further, in the second embodiment, an adjacent node management table 103a shown in FIG. 44 is used instead of the adjacent node management table 103 of the first embodiment shown in FIG. In the second embodiment, the adjacent node management table 103a also manages port IDs that identify ports used for connection with adjacent node devices.

By the way, in the first embodiment, a case where the node device 100 includes the PHY chip 202 of FIG. 4 for connection to an external network is illustrated. Similarly, the node device 100a according to the second embodiment includes a general-purpose LAN port 212a for connection to an external network.

The general-purpose LAN port 212a is a physical port for wired connection according to the Ethernet standard, for example, and is connected to a PHY chip (not shown). In FIG. 43, the general-purpose LAN ports 212a to 212i are indicated by hatching to distinguish them from the ports 211a-1 to 211i-4. The general-purpose LAN ports 212a to 212i in this embodiment are wired LAN ports, but a wireless LAN interface can be used instead depending on the embodiment.

Each of the node devices 100a to 100i having the configuration as described above is physically meshed (in other words, a lattice in a network 4) by a cable (for example, a metal wire cable such as a copper cable or an optical fiber cable). Connected). Of course, the physical connection topology in the network is arbitrary depending on the embodiment, and does not necessarily have to be a mesh.

In this embodiment, the mesh-like physical topology shown in FIG. 43 is realized by the following cable wirings (M1) to (M12).
(M1) The node devices 100a and 100d are connected by a link 515 between the ports 211a-1 and 211d-1.

(M2) The node devices 100a and 100b are connected by a link 516 between the ports 211a-4 and 211b-1.
(M3) The node devices 100b and 100e are connected by a link 517 between the ports 211b-2 and 211e-2.

(M4) The node devices 100b and 100c are connected by a link 518 between the ports 211b-4 and 211c-1.
(M5) The node devices 100c and 100f are connected by a link 519 between the ports 211c-3 and 211f-3.

(M6) The node devices 100d and 100g are connected by a link 521 between the ports 211d-2 and 211g-2.
(M7) The node devices 100d and 100e are connected by a link 522 between the ports 211d-4 and 211e-1.

(M8) The node devices 100e and 100h are connected by a link 523 between the ports 211e-3 and 211h-3.
(M9) The node devices 100e and 100f are connected by a link 524 between the ports 211e-4 and 211f-1.

(M10) The node devices 100f and 100i are connected by a link 525 between the ports 211f-4 and 211i-4.
(M11) The node devices 100g and 100h are connected by a link 526 between the ports 211g-4 and 211h-1.

(M12) The node devices 100h and 100i are connected by a link 527 between the ports 211h-4 and 211i-1.
Of course, according to the embodiment, it is also possible to realize a mesh topology equivalent to that of FIG. 43 by connecting ports of combinations other than those illustrated in FIG. 43 with cables.

Incidentally, in the example of FIG. 43, the network 4 is not an isolated network, but is also connected to an external network such as a LAN or a WAN (Wide Area Network). For example, in the example of FIG. 43, the network 4 is connected to the external network as follows. That is, an L2SW (Layer 2 Switch) 502 connected to a PC (Personal Computer) 501 via a link 511 is connected to general-purpose LAN ports 212a and 212b of the node devices 100a and 100b via links 512 and 513, respectively. Has been. The PCs 503, 505, and 506 are connected to the general- purpose LAN ports 212c, 212g, and 212h of the node devices 100c, 100g, and 100h via links 514, 528, and 529, respectively.

Note that the L2SW 502 may be further connected to a router (not shown) or another PC (not shown). The PCs 503, 505, and 506 may also be connected to another external network (not shown).

For convenience of explanation, FIG. 43 illustrates the network 4 including nine node devices 100a to 100i. However, depending on the embodiment, a large number of node devices such as thousands to hundreds of thousands may be connected to the wired ad hoc network. May be included. For example, the wired ad hoc network of this embodiment may be applied to a sensor network that is a network for collecting various information from a large number of sensors arranged everywhere. In that case, in correspondence with a large number of sensors, the wired ad hoc network may include a large number of node devices on the order of thousands to hundreds of thousands. In the sensor network, for example, any type of sensor such as an image sensor, a temperature sensor, a humidity sensor, a pressure sensor, and an acceleration sensor is used.

FIG. 43 also shows one example of application of the wired ad hoc network according to the present embodiment to the sensor network. That is, in FIG. 43, sensors 504 and 507 having a LAN interface are connected to general- purpose LAN ports 212e and 212i of the node devices 100e and 100i via links 520 and 530, respectively. The sensors 504 and 507 output data indicating the sensed result as an Ethernet frame via the LAN interface. The types of these sensors 504 and 507 are arbitrary.

Thus, the second embodiment is premised on a network in which node devices are connected by a wired link. For this reason, the operation of the node device of the second embodiment is basically the same, although there are some differences from the first embodiment described above. Also in the second embodiment, similarly to the first embodiment, frame transfer efficiency is improved by using empty data frames or aggregated empty data frames in the backtrack operation. Further, although not particularly illustrated, even in a network in which wireless links and wired links are mixed, the frame transfer efficiency is improved as in the first or second embodiment.

<Others>
The node device according to the embodiment is, for example, the reception unit 101 in FIG. 3, the wireless module 206 in FIG. 4, and the ports 211a-1 to 211a in FIG. 211a-4 and a PHY chip connected thereto.

3 is realized by, for example, the DRAM 20 or the flash memory 205 of FIG. 4, and stores the information shown in FIGS. 12, 13, and 16. The FID management table 105 is an example of a storage unit that stores the following pieces of information (N1) to (N3) in association with each other.

(N1) Frame identification information for identifying a transmission target frame (N2) Transmission destination adjacent node identification information for identifying a transmission destination adjacent node device that is a transmission destination of the transmission target frame among a plurality of adjacent node devices (N3) transmission Origin Node Identification Information for Identifying Adjacent Node Device that Transmits Target Frame First The transmission target frame in (N1) is, for example, a data frame, an empty data frame, and an aggregated empty data frame shown in FIG. An example of the frame identification information is a combination of the value of the GS field and the value of the FID field.

A specific example of the destination adjacent node identification information (N2) is the node ID of the adjacent node device stored in the LD field of the FID management table 105.
A specific example of the origin node identification information (N3) is a node ID stored in the OLS field of the FID management table 105.

As described above, when the node device 100 relays the data frame, the value of the LS field of the data frame when the node device 100 first receives the data frame is stored in the OLS field of the FID management table 105. Is done. That is, the node ID of the adjacent node device that has transmitted the transmission target frame first is stored in the OLS field.

Further, the weighting table 104 in FIG. 3 is realized by the DRAM 204 and the flash memory 205 in FIG. 4 and stores the information shown in FIGS. The weighting table 104 is an example of a storage unit that stores transmission possibility information indicating transmission possibility to each of a plurality of adjacent node apparatuses in association with the GD that is the final destination of the data frame.

In the above embodiment, the transmission possibility information is specifically represented by one or a plurality of entries each including a set of a node ID and a weight value of the LD field. The transmission possibility is expressed as, for example, “If the weight value is 1, transmission is impossible, and if the weight value is less than 1, transmission is possible”.

Further, the data frame processing unit 110 in FIG. 3 is realized by the MPU 201 and the DRAM 204 in FIG. 4, for example, and is an example of an updating unit that updates transmission possibility information. When received frame identification information for identifying a received frame received by a receiving unit such as the receiving unit 101 is stored as (N1) frame identification information in a storage unit such as the FID management table 105, a data frame as an updating unit The processing unit 110 updates the transmission possibility information.

The data frame processing unit 110 and the transmission unit 102 cooperate to select a second adjacent node device that can transmit a frame from a plurality of adjacent node devices, and receive the second adjacent node device. It functions as a transmission means for transmitting a frame. The data frame processing unit 110 as a part of the transmission unit selects the second adjacent node apparatus based on the transmission possibility information associated with the reception frame destination and stored in the storage unit such as the weighting table 104. To do.

Also, the data frame processing unit 110 and the transmission unit 102 cooperate to function as backtracking means. The data frame processing unit 110 and the transmission unit 102 serving as backtracking units have no transmission capability information among the plurality of adjacent node devices in the transmission possibility information of the storage unit such as the weighting table 104, and the received frame identification information Is stored as frame identification information (N1) in the storage means such as the FID management table 105, at least a part of the received frame is transmitted to the third adjacent node device identified by the origin node identification information.

When the received frame is expected to be held in the third adjacent node device, the node device that performs backtracking transmits frame identification information that is a part of the received frame to the third adjacent node. “When the received frame is expected to be held by the third adjacent node device” means, for example, “the elapsed time from when the received frame is received is longer than the period during which the processing frame is held in each node device. Or “when the elapsed time from when the received frame is transmitted to the second adjacent node device is shorter than the period during which the processing frame is held in each node device”. Here, “when a received frame is received” or “when a received frame is transmitted to the second adjacent node device” corresponds to an entry time recorded in the FID management table 105 in the above-described embodiment. The frame identification information corresponds to the FID and GD included in the data header in the above-described embodiment. The frame identification information is transmitted by an empty data frame in the above-described embodiment.

When there are a plurality of pieces of frame identification information to be transmitted to the third adjacent node device, the plurality of pieces of frame identification information are stored and transmitted in one frame. A frame that stores a plurality of frame identification information corresponds to an aggregated empty data frame in the above-described embodiment.

Also, the node device includes a transmission queue that holds a received frame transmitted to the second adjacent node device as a frame holding unit. For example, the transmission queue holds the received frame from when the received frame is transmitted to the second adjacent node apparatus until at least a predetermined holding period elapses. In the embodiment described above, this holding time corresponds to, for example, an aging time for holding each entry in the FID management table 105.

Furthermore, when the frame identification information is notified from the second adjacent node device described above, the node device extracts a frame corresponding to the notified frame identification information from the transmission queue as the frame holding means. Then, the node device transmits the extracted frame to the adjacent node device determined based on the weight value as the transmission possibility information base.

Claims (8)

1. Receiving means for receiving data from one of a plurality of adjacent node devices;
   Data identification information for identifying transmission target data, transmission destination adjacent node identification information for identifying a transmission destination adjacent node device that is a transmission destination of the transmission target data among the plurality of adjacent node devices, and the transmission target data. First storage means for storing the source node identification information for identifying the source adjacent node device, which is the adjacent node device that has transmitted first, in association with each other;
   Second storage means for storing transmission possibility information indicating the transmission possibility of data to the final destination for each of the plurality of adjacent node identification information in association with the final destination of data;
   Based on the fact that the data identification information for identifying the data received by the receiving means is stored as the data identification information in the first storage means, the destination adjacent node identification associated with the data identification information Information is specified, and in the second storage means, the transmission possibility of the specified adjacent node identification information among the transmission possibility information of the adjacent node associated with the final destination set in the reception data is determined. An updating means for updating the transmission to impossible,
   Based on the transmission possibility information of the transmission destination adjacent node identification information associated with the final destination of the received data in the second storage means, the adjacent node device capable of transmission is selected, and the selected adjacent node device Transmitting means for transmitting the received data to:
   Based on the fact that all the transmission possibility information of the destination adjacent node identification information associated with the final destination of the reception data in the second storage means cannot be transmitted, the reception data in the first storage means Backtrack means for transmitting a part of the received data including at least the data identification information of the received data to the origin adjacent node device associated with the identification information;
   A node device comprising:
2. The node device according to claim 1,
   The backtrack means is configured such that an elapsed time from when the receiving means receives the received data or an elapsed time from when the transmitting means transmits the received data to the destination adjacent node device When the data is shorter than a period in which data is held in the node device, a part of the received data is transmitted to an adjacent node device indicated by the origin node identification information.
3. The node device according to claim 1,
   When there are a plurality of pieces of data identification information to be transmitted to the origin adjacent node device, the backtrack means stores the plurality of data identification information in one transmission unit data and transmits the data identification information.
4. The node device according to claim 1,
   The backtrack means is configured such that an elapsed time from when the receiving means receives the received data or an elapsed time from when the transmitting means transmits the received data to the destination adjacent node device The node device, wherein the received data is transmitted to the origin adjacent node device if it is longer than a period in which the processing data is held in the node device.
5. Receiving means for receiving data from one of a plurality of adjacent node devices;
   Data identification information for identifying transmission target data, transmission destination adjacent node identification information for identifying a transmission destination adjacent node device that is a transmission destination of the transmission target data among the plurality of adjacent node devices, and the transmission target data. First storage means for storing the source node identification information for identifying the source adjacent node device, which is the adjacent node device that has transmitted first, in association with each other;
   Second storage means for storing transmission possibility information representing the transmission possibility to each of the plurality of adjacent node devices in association with the final destination of the data;
   When reception data identification information for identifying reception data received by the reception means is stored as the data identification information in the first storage means, a transmission destination adjacent node identification associated with the data identification information Information is specified, and in the second storage means, the transmission possibility of the specified adjacent node identification information among the transmission possibility information of the adjacent node associated with the final destination set in the reception data is determined. An updating means for updating the transmission to impossible,
   Based on the transmission possibility information of the transmission destination adjacent node identification information associated with the final destination of the received data in the second storage means, the adjacent node device capable of transmission is selected, and the selected adjacent node device A transmission means for transmitting data to
   Data holding means for holding data including data identification information transmitted by the transmission means to the adjacent node device;
   With
   The transmission means extracts data from the data holding means based on the reception means receiving at least a part of data including the data identification information of the data transmitted by the own node apparatus from the transmission destination adjacent node apparatus. And transmitting the data.
6. The node device according to claim 5, wherein
   Based on the reception unit receiving data storing a plurality of data identification information from the destination adjacent node device, the transmission unit receives a plurality of data corresponding to the plurality of data identification information from the data holding unit. A node device characterized by extracting and transmitting a plurality of the extracted data.
7. A data transmission method used by a node device having a plurality of adjacent node devices,
   The node device is
   An extraction step of extracting data identification information for identifying the data from data received from one of the plurality of adjacent node devices;
   Data identification information for identifying transmission target data, transmission destination adjacent node identification information for identifying a transmission destination adjacent node device that is a transmission destination of the transmission target data among the plurality of adjacent node devices, and the transmission target data The data identification information extracted in the extraction step is referred to by referring to a first storage means that stores the source node identification information that identifies the source adjacent node that is the neighboring node device that has been transmitted first. A determination step of determining whether or not the data is stored in the first storage means;
   When the data identification information is stored in the first storage means, the transmission neighboring node identification information associated with the data identification information is specified, and then the plurality of neighbors are associated with the final destination of the data. Reference is made to second storage means for storing transmission possibility information indicating the transmission possibility of data to the final destination for each node identification information, and the final destination set in the received data in the second storage means An update step of updating the transmission possibility of the identified adjacent node identification information among the transmission possibility information of the adjacent nodes associated with
   Based on the transmission possibility information of the transmission destination adjacent node identification information associated with the final destination of the received data in the second storage means, the adjacent node device capable of transmission is selected, and the selected adjacent node device Transmitting the received data to:
   Based on the fact that all the transmission possibility information of the destination adjacent node identification information associated with the final destination of the reception data in the second storage means cannot be transmitted, the reception data in the first storage means A backtrack step of transmitting at least a part of the received data including at least the data identification information of the received data to the origin adjacent node device associated with the identification information. Method.
8. A data transmission method for a node device having a plurality of adjacent node devices,
   The node device is
   An extraction step of extracting data identification information for identifying the data from data received from one of the plurality of adjacent node devices;
   Data identification information for identifying transmission target data, transmission destination adjacent node identification information for identifying a transmission destination adjacent node device that is a transmission destination of the transmission target data among the plurality of adjacent node devices, and the transmission target data Judgment whether or not the extracted data identification information is stored in the first storage means that stores the origin node identification information that identifies the origin adjacent node device that is the neighboring node device that has been transmitted first in association with each other A decision step to
   When the data identification information is stored in the first storage means, the destination adjacent node identification information associated with the data identification information is specified, and then the plurality of data are associated with the final destination of the data. Reference is made to second storage means for storing transmission possibility information representing the possibility of transmission of data to the final destination for each adjacent node identification information, and the final set in the received data in the second storage means An update step of updating the transmission possibility of the specified adjacent node identification information among the transmission possibility information of the adjacent nodes associated with the destination to be non-transmissible;
   Based on the transmission possibility information of the transmission destination adjacent node identification information associated with the final destination of the received data in the second storage means, the adjacent node device capable of transmission is selected, and the selected adjacent node device Transmitting the received data to:
   A holding step of holding data including data identification information transmitted to the destination adjacent node device in a data holding unit;
   With
   In the transmission step, based on receiving a part of data including at least the data identification information transmitted by the own node device from the transmission destination adjacent node device in the reception step, the data is extracted from the data holding step, A data transmission method comprising: transmitting the data.

Images