JP2003298594A - Path selecting method and node in network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a path selecting method for dynamically selecting other link when a link once setup is interrupted and surely transmitting a packet to a prescribed destination node even when an initially set link is interrupted. <P>SOLUTION: The path selecting method in the network of this invention whereby a transmission intending node searches a proper node capable of relaying a link with a transmission destination node when the link is interrupted on the way of packet communication by setting up a link b-M-f by the transmission intention node b, the transmission destination node f via a master node M, and selects the node as a relay node when a relay enabled node d is found out and transmits data to the initial transmission destination node f by way of a path of b-d-M-f so as to enhance the communication reliability. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a route selection method in a network capable of dynamically forming a new link and transmitting data to a predetermined destination node even in the case where communication cannot be restored due to interruption of an initial setting link. Regarding the node.

[0002]

2. Description of the Related Art Conventionally, in a network formed by a single route, when a link between certain nodes is broken and communication becomes impossible, a method of repeatedly making a link on the same link is used.

[0003]

However, in the conventional method, in a communication environment in which the processing setting link is cut off and relinking is impossible, data communication cannot be resumed and the reliability of network communication is low. there were.

The present invention has been made in view of such conventional problems. Even when a link once established is cut off, another link is dynamically selected and generated, and the initial setting link is broken. Even so, it is an object of the present invention to provide a network route selection technique capable of reliably transmitting a packet to a predetermined destination node.

[0005]

According to the invention of claim 1, there is provided a route selection method in a network having a node including at least a layer below Bluetooth L2CAP, a Bluetooth profile layer, an upper network layer and an application layer. When it is determined that communication is not possible because the link with a predetermined node is disconnected when the intended node intends to transmit, it searches for a communicable node among neighboring nodes, and (2) communication found by the search. If the address of the possible node is equal to the intended destination node, the node of the address is selected to establish the link, and (3) the address of the communicable node found by the search. If there is no equivalent to the intended destination node, the address of any one of the communicable nodes is Mode is selected to establish a link, and the node having the address selected in (4), (2) or (3) investigates whether or not the packet can be sent to the intended node of the communication partner, and (5) the investigation described above. If the packet can be sent to the intended node of the communication partner by (6), the initial packet is sent. (6) If the packet cannot be sent to the node of the intended communication partner by the investigation, the node of another arbitrary address is sent. It is characterized by repeating an attempt to select and establish a link and investigate whether or not a packet can be sent.

According to a second aspect of the invention, in the route selection method in the network of the first aspect, as a result of the search of the neighbor node by the transmission intention node, all the addresses for each node included in the packet returned from each communicable node. Is held in the transmission intention node as a list, any address in this list is once connected as a connection candidate, and a response request packet is sent to the address of the communication destination node,
If there is no response, select another address in the list, connect once, repeat the procedure of sending a response request packet to the address of the communication destination node, and if there is a response to the response request packet, connect now It is characterized in that the node having the medium address is selected as a relay node to the communication destination node.

According to a third aspect of the present invention, in the route selection method for a network according to the first or second aspect, when there is no link key generated in advance, a PIN code is previously set as a relay PIN code to a node which permits relay. It is characterized in that it is allocated and then used to generate an authentication link key in the route search process for mutual authentication.

According to a fourth aspect of the present invention, in the route selection method for a network according to the first to third aspects, the transmission intention node sets the destination MAC address as the broadcast address after the link is established, and sets the network address of the destination node as the destination. The node that transmits the response request packet having the address as an address, and the node that receives the response request packet transmits the response packet whose destination is the source network address, and if the response packet is returned to the transmission intention node, the transmission partner The transmission data is transmitted by using the network address of the destination node as the destination address.

In the route selection method in the network according to the first to fourth aspects of the present invention, the link is cut off during the packet communication while the transmission intention node establishes the link with the transmission destination node via the master node. When
The transmission intention node searches for an appropriate node that can relay the link with the destination node, and if it can find a relayable node, it selects that node as a relay node and relays the node to the original destination node. Increase the reliability of communication by transmitting data to the node.

Even when the node of the invention of claim 5 is not set as the master node, the node forming means forms a link with a plurality of other nodes in a time division manner, and when it receives a packet not addressed to itself, it transmits the packet. And a packet transfer means for transferring a packet to another link destination node which is not the original.

In the node of the invention of claim 5, the other transmission intention node establishes a link with another transmission destination node via the master node and the link is cut off during packet communication, and the time node Is selected as a relayable node, and when a transmission packet from the transmission intention node to the transmission destination node is received, the packet is transferred to another link destination node that is not the transmission source.
As a result, it can be used as a node of a network that uses the route selection method in the network of the first to fourth aspects of the invention, and can contribute to the construction of a highly reliable network.

According to a sixth aspect of the present invention, in the node of the fifth aspect, the node operates as a master having a function of forming a link with a plurality of other nodes in a time division manner, and when a packet is received from another node. , If the destination address shown in the packet does not match the address in the destination address table held by itself, the received packet is transferred to the node operating as the master of another link destination and held. If the address matches the address in the destination address table, the packet has a function of transferring the packet received to the address.

According to another aspect of the present invention, when the node receives a packet from another node, the destination address indicated in the packet matches the address in the destination address table held by itself. If not, the received packet is transferred to the node operating as the master of another link destination, and if it matches the address in the held destination address table, the packet received to that address is transferred. Because you can
When a node that intends to send is establishing a link with the destination node and the link is cut off during packet communication and another node is selected as a relayable node, that node becomes the destination node. Alternative routes to reach can be formed automatically. Thereby, claim 1
It can be used as a master node of a network that uses the route selection method in the network of the invention of 4, and can contribute to the construction of a highly reliable network.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is one of the short-range wireless standards, Blueto
It is an example of a connection form of the oth network. The link state of FIG. 1 is a state in which each of the plurality of slave nodes a to f is linked to the master node M. In this link state, the node b is in data communication with the node f through the route bMf, and now the link l between bM is
-BM is blocked. In that case, node b-
Communication between f becomes impossible.

In FIG. 2, a master b is a master / slave node (M / S) and a master M is a node from a node a1 to a node f.
The link state of the piconet in the case of transmitting the packet through the route of a1-b-M-f passing through. Even in this case, if the link 1-a1b is cut off, communication between the nodes a1-f cannot be performed.

The functional characteristic of the network according to one embodiment of the present invention is that, in the case as shown in FIG.
(i) If there is a response from the destination node node f, a direct link is established. (ii) If there is no response from the node f, but there is a response from the nodes d and e, , Searching the route of each node, for example, node d
If the d-Mf link is not established and the e-Mf link is established for the node e, the node e is selected as an alternative node, and the node b is the b- e-
The point is that the link with the original destination node f is reestablished in the route of Mf and data communication is restarted.

Further, in the case of FIG. 2, in the network of this embodiment, the node a1 first tries to relink the node b, and if the relinking is not possible, an inquiry is broadcast. Then, (i) there is a response from the nodes d and e. Now, the node d is first selected, the link with the destination node f is inspected for the node d, and d-
If the Mf link is not established, node d is excluded from the candidates and node e is selected. (Ii) With respect to the node e, the link with the destination node f is checked, and if the link of e-Mf is established, the node a1 selects the node e as an alternative node and a1-e-M-f. The data communication with the destination node f is restarted by the route.

As described above, in the network of this embodiment, when the initial link is cut off, an alternative route is automatically searched for, and a link on another route between the original node and the destination node is automatically selected. By using the route selection function, the reliable communication characteristic is secured.

Next, the functional configurations of the node and the master used in the network of this embodiment will be described. Figure 5
As shown in FIG. 1, any node 11 whether it is a master or a slave has a layer below the Bluetooth L2CAP 12, a blue layer.
It is composed of a tooth profile layer 13, a TCP / IP layer 14, and an application layer 15.

The TCP / IP layer 14 is not limited to this, and may be any network as long as it holds at least one network address. In addition, the layer below Bluetooth L2CAP 11 has a MAC address as an address unique to the medium. In the following description, this is set to the Bluetooth address (BD_ADD
R).

Further, AM_ADDR is an address unique to Bluetooth and is a value within 3 bits which is given to an active slave under the control of the master M, and PM_ADDR
_ADDR is a value given to the sleeping slave, and is theoretically a value within 48 bits.

In the state shown in FIG. 1 or 2, each node has already acquired the network address.
In the protocol stack of FIG. 5, TCP / I
The interface between the P layer 14 and the Bluetooth profile layer 13 and below is H which is incorporated in the Bluetooth module.
It is a CI (Hardware Control Interface), and the following various functions depend on software.

As shown in FIG. 6, in each node 11, when the payload data 21 is passed from the application layer 15, the TCP / IP layer 14 receives a predetermined header and a destination IP.
The address 22 is attached and passed to the Bluetooth profile layer 13. The profile layer 13 further includes a header A23 and a data string 24 having a so-called Bluetooth address as a destination address and a self address for the received data.
And is added and passed to the layer 12 below the Bluetooth L2CAP.
Then, in the layer 12 below the Bluetooth L2CAP, a header B25 and a BL called AM-ADDR or PM-ADDR
A destination address defined by the uetooth standard is added as a data string 26, and the data string 26 is transmitted to the other party.

(1) The master node (for example, the master M or the master / slave M / S) that has received the packet data from another node checks the Bluetooth profile layer 13. If (a) the destination Bluetooth address is not addressed to the own device, the Bluetooth address registered in the own device and AM_ADDR or PM_AD
Search for the corresponding AM_ADDR or PM_ADDR from the conversion table with DR, and use this as the destination for Bluetooth
It is passed to the layer 12 below the L2CAP. (B) On the other hand, if the received destination Bluetooth address is a packet addressed to itself, the packet is regarded as addressed to the own device and processed.

(2) The slave node having only a single link passes it to the TCP / IP layer 14 if the destination Bluetooth address of the packet received by the Bluetooth profile layer 13 matches its own address, and discards it if it does not match. In this case, there is no transfer function to the master.

Next, the automatic route selection processing by the above-mentioned network will be described with reference to the sequence diagram of FIG.
An automatic route selection process corresponding to the case shown in will be described.

In S0, if the link b-M-f is established and the link b-M is cut off, the link b-M is cut off when the node b tries to transmit a packet. When this is detected, the link is reestablished. If the relink cannot be established, an inquiry is transmitted by broadcast in S1 to search for a neighboring node.

The neighboring nodes have a function of performing an inquiry scan at a fixed cycle, and S2
Responds to the Inquiry of node b, and Blu
Send back a response packet containing the etooth address. At this time, the Bluetooth address of each node included in the packet returned from each node is held in the node b as a list in the form of the list 31 shown in FIG. The characters in each line of the list 31 shown in FIG. 4 represent the MAC address of each node.

In step S3, the node b preferentially selects the node having the same Bluetooth address as the original destination Bluetooth address in the received list 31 of the Bluetooth addresses of the respective nodes, and the nodes b are selected in S4 and S5. The Page operation is applied to the node f, and after the link is confirmed, the authentication is started (S
6). In this case, the authentication is performed between the node b and the node f, and if the link key is held, this link key value is used, and if not held, the link key for authentication in this route search processing is preliminarily used. A link key is generated using the relay PIN code registered for generation, and mutual authentication is performed. In this case, the relay PIN code is a code that is provisionally assigned in advance to a node that permits this when a certain node is used for relay. For security reasons, it is desirable to delete the link key generated by the relay PIN code when the route search process is completed.

Next, in S7, according to the Bluetooth protocol,
Check SDP and Profile, and if correct, it means that the link generation between node b and node f has been completed, and TC
The conditions for P / IP communication have been established (S
8).

Next, in S9 and S10, the node b transmits a response request packet (PING packet) with the destination IP address destined for the IP address of the destination node originally destined for transmission. Here, the PING packet is the packet structure shown in the Bluetooth profile layer 13 in the packet data structure of FIG. That is.

The node receiving the PING packet
Send the destination as the source IP address to the source (S1
1). In S12, the transmission source node b transmits a regular packet when the PING response is returned.

In the case of the above simple example, the PING packet should be returned without exception, but when the node b selects the node d and becomes the route b−d−M−f, the link between d−M If is blocked, no PING packet is returned. Further, even in the case of a complicated configuration such as the network of FIG. 2, the PING packet may not always be returned. In such a case, in S13, the node b
The process of 3) b), that is, another node is selected from the slave selection candidates, the page operation of S4 and subsequent steps are repeated again, and the PING packet is confirmed. The network shown in FIG. 2 is called a "scatternet", and has one communicable link for each time zone in time division, while other links are linked in the HOLD mode. It is a rule that communication is suspended while holding.

Further, in the network having the configuration of FIG. 2, the node a1 selects the node e instead of the node b, and instead of the route a1-b-Mf, a1-e-M-.
If the route of f is selected and there is no communication between the nodes e and M, the node a1 selects the node d in the process of b) of S3 of the sequence diagram of FIG. 3, and the node a1−d−M−f PING is performed on the route, and if successful, the node a1 transmits a regular packet to the node f on this route.

Furthermore, when a node that is not the master node receives a packet that is not addressed to itself, it has a function of forwarding the packet to the other node that is the link partner that is not the transmission source. As a communication rule, for the purpose of this route search process, a slave node that has links with multiple nodes does not discard the received packet even if the destination of the received packet is not the Bluetooth address of the device itself. It shall be transferred to the linked node.

The master node M or the master / slave node M / S has the address table 32 shown in FIG.
Hold. When the nodes M and M / S act as masters, the address table 32 has a destination AM_ADDR and a destination PM_A corresponding to BD_ADDR (Bluetooth address) of a slave node under this management.
It is a table of DDR. Then, when these nodes receive the packet, the destination Blueto in the packet
oth address is the address table 3 held by the device itself
If it matches the destination Bluetooth address in 2, the data is transmitted to the corresponding AM_ADDR or PM_ADDR.
Also, the destination Bluetooth address holds the table 3
If it does not match the Bluetooth address in 2, the communication rule is to transfer the received packet to the M node or M / S node of another link destination.

When the message transmission is completed in S12 of the sequence of FIG. 3, the link is cut off (S14). In addition,
In this case, the configuration may be such that the link is held in the HOLD mode while waiting.

In this way, if another route is selected and the required data transmission is completed by the selected route, the original link that was initially cut off is retried (S15, S).
16).

[0039]

As described above, according to the route selection method in the network of the first to fourth aspects of the invention, the transmission intention node establishes a link with the transmission destination node via the master node and performs packet communication. If the link is interrupted during the process, the transmission intention node searches for an appropriate node that can relay the link with the destination node, and if a node that can relay is found, selects the node as a relay node, Data can be transmitted to the original destination node by relaying the node, and the reliability of communication can be improved.

According to the node of the invention of claims 5 and 6,
It can be used as a node of a network that uses the route selection method in the network according to the first to fourth aspects of the invention, and can contribute to the construction of a highly reliable network.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of one link mode of a Bluetooth network.

FIG. 2 is an explanatory diagram of another link mode of the Bluetooth network.

FIG. 3 is a sequence diagram of a route selection processing operation by the network according to the embodiment of this invention.

FIG. 4 is an explanatory diagram of an address list of a response node acquired as a result of a route search by the transmission intention node in the above embodiment.

FIG. 5 is a protocol stack diagram of a node in the above embodiment.

FIG. 6 is a frame configuration diagram in each layer of transmission data by the node in the above embodiment.

FIG. 7 is an explanatory diagram of an address list held by the master node in the above embodiment.

[Explanation of symbols]

af nodes a1-e1 nodes M master M / S master / slave

Claims (6)

[Claims] 1. At least a layer below Bluetooth (Bluetooth) L2CAP, a Bluetooth profile layer,
A route selection method in a network having a node composed of an upper network layer and an application layer, wherein (1) it is determined that communication is impossible due to disconnection of a predetermined link with a predetermined node when the transmission intention node intends to transmit. To search for a communicable node among neighboring nodes, and (2) if the address of the communicable node found by the search is equal to the intended destination node, the node of the address is searched. (3) If none of the addresses of the communicable nodes found by the search is equal to the intended destination node, any one of the communicable nodes is selected. The node with the address selected in (4), (2), or (3) is selected as the intended communication partner. It is investigated whether or not the packet can be sent to the node, (5) If the packet can be sent to the intended communication partner node by the above investigation, an initial packet is sent, and (6) to the intended communication partner node by the above investigation. A method for selecting a route in a network, characterized in that if a packet cannot be sent, a node having another arbitrary address is selected to establish a link, and an attempt to check whether or not the packet can be sent is repeated. 2. As a result of searching for a neighboring node by the transmission intention node, all addresses for each node included in the packet returned from each communicable node are held in the transmission intention node as a list, and any of the list is stored. Address as a connection candidate, and then send a response request packet to the address of the communication destination node.If there is no response, select another address in the list and connect once, and 2. The procedure of sending a response request packet to an address is repeated, and if there is a response to the response request packet, the node of the currently connected address is selected as a relay node to the communication destination node. Route selection method in the Internet. 3. When a pre-generated link key does not exist, a PIN code is assigned in advance to a node that permits relay as a relay PIN code, and the PIN code is used for authentication in a route search process. 3. The route selection method in the network according to claim 1, wherein the route selection method is performed and mutual authentication is performed. 4. The node intended to send, after the link is established, transmits a response request packet having the destination MAC address as the broadcast address and the network address of the transmission destination node as the destination address, and receiving the response request packet. Transmits a response packet having a destination as a transmission source network address, and when the response packet is returned to the transmission intention node, transmits transmission data with the network address of the transmission destination node as a destination address. A route selection method in the network according to claim 1. 5. A link forming unit that forms a link with a plurality of other nodes in a time-division manner even when it is not set as a master node, and another link partner that is not the transmission source when a packet not addressed to itself is received. A node comprising a packet transfer means for transferring a packet to the node. 6. When operating as a master having a function of forming a link with a plurality of other nodes in a time division manner, when a packet is received from another node, the destination address indicated by the packet is If it does not match the address in the destination address table held by itself, the received packet is transferred to the node operating as the master of another link destination, and the received packet matches the address in the held destination address table. The node according to claim 5, further comprising a function of transferring a packet received to the address, if it is done.