JP2010161795A - Communication node and token ring communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a method for issuing a token of a ring-shaped communication system which specifies an issuance of a token frame in the ring-shaped communication system. <P>SOLUTION: A communication node includes a communication right acquisition processing unit which transmits a token reception completion notification frame addressed to a transmission source communication node of the token frame when the token frame is obtained and a communication right is obtained, and releases the token frame when a transmission process of a data frame ends, a logical ring state control unit which switches a mode between a transmission mode in which a logical connection in the communication node is disconnected when the communication right is obtained and a repeat mode in which the disconnection of the logical connection in the communication node ends when the token reception completion notification frame addressed to the communication node is received, and data frame communication processing means for transmitting and receiving the data frame. The data frame communication processing means dispose of all the received frames in a case of state of the transmission mode and transfer the received frame in a case of state of the repeat mode. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication node used in an Ethernet (registered trademark) -based ring communication system that performs communication by connecting Ethernet (registered trademark) in a ring shape, and to perform masterless token ring communication in the communication system. The present invention relates to a token ring communication method of the ring communication system.

  2. Description of the Related Art Conventionally, a form in which a network is constructed by connecting communication terminals (hereinafter referred to as communication nodes) using FDDI (Fiber-Distributed Data Interface) is known (see, for example, Non-Patent Document 1). In this FDDI, a network is generally constructed to connect communication nodes in a ring shape. In a network using FDDI, when an abnormality such as a disconnection of a cable constituting the first loop or a failure of a communication node occurs in the first loop in which data is transmitted in a normal state, the abnormal portion is networked. A double loop structure comprising a second loop configured to perform communication in a normal part by performing loop back so as to be separated from the loop is adopted.

  Further, FDDI employs a token passing system for controlling transmission of data transmitted between communication nodes connected to a network by using transmission right data called a token. In this token passing method, the token is flowed on the first loop, and the communication node that wants to transmit data captures and captures this token, and instead flows the data that it wants to transmit. Is released to the network, so that one terminal always uses a cable at a time.

Karl F. Pieper, William J. Cronin Jr., Wendy H. Michael, translated by Naoki Mizuma, "FDDI Technical Details-100Mbps LAN Construction", First Edition, Kyoritsu Publishing Co., Ltd., August 30, 1993, p . 67-73

  By the way, at present, a configuration in which communication nodes are connected by Ethernet (registered trademark) to construct a network is widespread. This Ethernet (registered trademark) secures a communication right while avoiding a collision when a communication node connected to the Ethernet (registered trademark) transmits data, and propagates data to all connected communication nodes. CD (Carrier Sense Multiple Access / Collision Detection) method is adopted. In order to make this system function, the connection form of communication nodes in Ethernet (registered trademark) includes a single cable serving as a trunk line, a branch cable extending from the cable at an appropriate interval, and a plurality of communication nodes. There are two topologies: a bus topology configured by arranging a plurality of communication nodes and a star topology configured by radiating a plurality of communication nodes around a single control device (hub).

  However, in Ethernet (registered trademark), since the terminal device connected to the network performs termination (discard) of the Ethernet (registered trademark) frame, the bus topology and the star topology described above exist, but the ring topology There was a problem that the topology did not exist. For this reason, for example, in a ring topology network constructed by Ethernet (registered trademark), a token issuing method and a token ring communication method for performing token ring communication have not existed conventionally.

  The present invention has been made in view of the above, and an object thereof is to obtain a communication node for performing token ring communication in a ring topology constructed by Ethernet (registered trademark). Further, the ring communication system of the ring communication system that prescribes the issuance of token frames in the Ethernet (registered trademark) -based ring communication system and the method of performing the token passing communication in the Ethernet (registered trademark) based ring communication system. Another object is to obtain a token ring communication method.

  To achieve the above object, a communication node according to the present invention is a communication node constituting a communication system in which a plurality of communication nodes connected by Ethernet (registered trademark) are connected in a ring shape, and obtains a token frame. Acquiring a communication right, a token reception completion notification frame destined to the transmission source communication node of the token frame is transmitted, and when the data frame transmission process is completed, a communication right acquisition processing means for releasing the token frame; When the communication right is acquired, when the transmission mode for disconnecting the logical connection in the own communication node and the token reception completion notification frame addressed to the own communication node are received, the disconnection of the logical connection in the own communication node is terminated. Logical ring state control means for switching the state between repeat mode and data frame transmission / reception. Data frame communication processing means, wherein the data frame communication processing means discards all received frames in the transmission mode state and transfers the received frames in the repeat mode state. Features.

  According to the present invention, for each communication node, a communication node that has acquired a communication right receives a transmission mode in which the ring is logically disconnected within the communication node, and a communication node that has not acquired the communication right. Since the repeat mode for transferring the frame is provided, there is an effect that the communication node that has acquired the communication right can discard the frame originating from the own communication node without causing fragmentation.

FIG. 1 is a diagram schematically showing a schematic configuration of an Ethernet (registered trademark) -based ring communication system according to the present invention. FIG. 2 is a block diagram schematically showing a configuration of a communication node constituting the ring communication system of FIG. FIG. 3 is a block diagram schematically showing a functional configuration of the communication node according to the first embodiment. FIG. 4A is a diagram schematically illustrating an example of a procedure of a token start right acquisition process in the ring communication system (part 1). FIG. 4-2 is a diagram schematically illustrating an example of a procedure of a token-start-right acquisition process in the ring communication system (part 2). FIG. 4-3 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 3). 4-4 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 4). 4-5 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 5). FIG. 4-6 is a diagram schematically illustrating an example of a procedure of a token-start-right acquisition process in the ring communication system (part 6). 4-7 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 7). FIG. 4-8 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 8). FIG. 4-9 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 9). FIG. 4-10 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 10). 4-11 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 11). FIG. 4-12 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 12). FIG. 4-13 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 13). FIG. 4-14 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 14). 4-15 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 15). FIG. 5 is a block diagram schematically showing a functional configuration of the communication node according to the second embodiment. FIG. 6A is a diagram schematically illustrating an example of a procedure of a token start right acquisition process in the ring communication system (part 1). FIG. 6-2 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 2). FIG. 6-3 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 3). FIG. 6-4 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 4). 6-5 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 5). FIG. 6-6 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 6). 6-7 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 7). 6-8 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 8). FIG. 6-9 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 9). FIG. 6-10 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 10). FIG. 6-11 is a diagram schematically illustrating an example of a procedure of a token-start-right acquisition process in the ring communication system (part 11). FIG. 6-12 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 12). FIG. 6-13 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 13). FIG. 6-14 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 14). FIG. 6-15 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 15). FIG. 6-16 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 16). FIG. 6-17 is a diagram schematically showing an example of a procedure of a token-start-right acquisition process in the ring communication system (part 17). FIG. 7 is a block diagram schematically showing a functional configuration of the communication node according to the third embodiment. FIG. 8-1 is a diagram showing an example of a communication processing procedure using the token passing system in the ring communication system (part 1). FIG. 8-2 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 2). FIG. 8-3 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 3). FIG. 8-4 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 4). FIG. 8-5 is a diagram showing an example of a communication processing procedure using the token passing system in the ring communication system (part 5). FIG. 9-1 is a diagram showing an example of a communication processing procedure using the token passing system in the ring communication system (part 1). FIG. 9-2 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 2). FIG. 9-3 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 3). FIG. 10-1 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 1). FIG. 10-2 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 2). FIG. 11-1 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 1). FIG. 11-2 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 2). FIG. 11-3 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 3). FIG. 11-4 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 4). FIG. 11-5 is a diagram illustrating an example of a communication processing procedure using the token passing system in the ring communication system (part 5). FIG. 12 is a block diagram schematically showing a functional configuration of the communication node according to the seventh embodiment. FIG. 13A is a diagram schematically illustrating an example of a procedure of token frame reproduction processing due to loss of a token frame (part 1). FIG. 13-2 is a diagram schematically illustrating an example of a procedure of token frame reproduction processing due to the disappearance of the token frame (part 2). FIG. 13C is a diagram schematically illustrating an example of a procedure of token frame reproduction processing due to loss of a token frame (part 3). FIG. 13-4 is a diagram schematically illustrating an example of a procedure of token frame reproduction processing due to loss of a token frame (part 4).

  Exemplary embodiments of a communication node and a token ring communication method according to the present invention will be explained below in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments. In the following, the outline of the configuration of the present invention common to the respective embodiments will be described, and thereafter, the respective embodiments will be described.

  FIG. 1 is a diagram schematically showing a schematic configuration of an Ethernet (registered trademark) -based ring communication system according to the present invention. This ring communication system has a configuration in which a plurality of communication nodes (communication devices, denoted as nodes in the figure) 10-1 to 10-4 connected one-to-one by Ethernet (registered trademark) are connected in a ring shape. Have Here, the Ethernet (registered trademark) cable connecting the communication nodes 10-1 to 10-4 is connected to the normal ring 1 that carries the frame clockwise in the ring communication system in the figure indicated by the solid line, and the dotted line. It is physically duplicated by two rings with a standby ring 2 that carries a frame in the counterclockwise direction shown in FIG. The normal ring 1 is a ring that is used when the communication nodes 10-1 to 10-4 and the cable constituting the ring communication system are in a normal state. Further, when an abnormality occurs in any one of the communication nodes 10-1 to 10-4 and the cables constituting the ring communication system, the standby ring 2 detects the abnormal part by a loopback process as described later. A ring used to separate from the system.

  FIG. 2 is a block diagram schematically showing a configuration of a communication node constituting the ring communication system of FIG. The communication node 10 includes two ports 11 and 14 for connecting an Ethernet (registered trademark) cable between adjacent communication nodes, processing of frames received from the ports 11 and 14, and between other communication nodes. And a communication processing unit 17 that performs processing for establishing the route.

  The port is composed of two ports, an A port (indicated as Port A in the figure) 11 and a B port (indicated as Port B in the figure) 14. The A port 11 includes a normal input unit 12 that receives a frame from the normal ring 1 and a standby output unit 13 that transmits a frame to the standby ring 2. The B port 14 includes a normal output unit 16 that transmits a frame to the normal ring 1 and a standby input unit 15 that receives a frame from the standby ring 2.

  The communication processing unit 17 once reads a frame from the normal system ring 1 received by the normal system input unit of the A port 11, performs a predetermined process when necessary, and then from the normal system output unit of the B port 14. While transmitting to the normal ring 1, the frame from the standby ring 2 received at the standby input unit of the B port 14 is not read and transmitted as it is to the standby output unit of the A port 11. More specifically, when necessary, a predetermined process is performed only on a frame output from the B port 14 in a normal state, and a frame flowing from the B port 14 to the A port 11 in the communication node is determined. No processing is performed.

  When such an Ethernet (registered trademark) -based ring communication system is constructed, each communication node 10-1 to 10-4 constituting the system is configured such that the network to which it belongs constitutes a ring-shaped route. A ring establishment confirmation process is performed to confirm whether or not After the ring establishment confirmation process is completed, the communication nodes 10-1 to 10-4 constituting the system distribute the station information of the own communication nodes necessary for creating the network configuration information to each other. The network configuration information including the positional relationship between the communication nodes 10-1 to 10-4 and the number of communication nodes 10-1 to 10-4 configuring the network is transmitted. As a result, normal communication can be performed in the Ethernet (registered trademark) -based ring communication system. The following embodiments are premised on processing in a network in which ring establishment confirmation processing and network configuration information creation processing have been completed. In the following embodiments, it is assumed that an Ethernet (registered trademark) -based ring communication system performs data communication by the token passing method.

  The above is the outline of the Ethernet (registered trademark) -based ring communication system common to the embodiments. Hereinafter, each embodiment will be described based on this content. In the following description, the communication nodes 10-1, 10-2, 10-3, and 10-4 are represented as 1 station, 2 stations, 3 stations, and 4 stations, respectively.

  Also, in this specification, for the sake of simplicity of explanation, a case where the ring communication system is configured by four communication nodes 10-1 to 10-4 will be described as an example. The following embodiments of the present invention can be applied as long as the network is configured to be connected in a ring shape by Ethernet (registered trademark).

Embodiment 1 FIG.
In the first embodiment, in the Ethernet (registered trademark) -based ring communication system, after the ring establishment confirmation process and the network configuration information creation process are finished, which communication node performs the token frame for performing the token ring communication. A token issuing method for determining whether to issue will be described.

  FIG. 3 is a block diagram schematically showing a functional configuration of the communication node according to the first embodiment. The communication processing unit 17 of the communication node 10 according to the first embodiment includes a token start right acquisition processing unit 21 and a token start processing unit 22. In addition, the same code | symbol is attached | subjected to the component same as the description mentioned above, and the description is abbreviate | omitted.

  The token start right acquisition processing unit 21 performs processing for acquiring a token start right for issuing a token frame after the above-described ring establishment confirmation processing and network configuration information creation processing are completed. In the first embodiment, unique information having the smallest value among communication nodes constituting a network is assigned using unique information unique in the world (no duplication occurs) such as a MAC (Media Access Control) address. The case where a token start right is given to the designated communication node is shown.

  In this case, after completing the ring establishment confirmation process and the network configuration information creation process, the token start right acquisition processing unit 21 transmits a token start right acquisition frame in which the unique information of the communication node is embedded at a predetermined time interval. To send. Also, the unique information in the token start right acquisition frame received from another communication node is compared with the unique information of the own communication node, and if the own communication node is smaller, the token start right acquisition frame is continuously transmitted. At the same time, the compared token start right acquisition frame is discarded. When the communication node is larger, the transmission of the token start right acquisition frame is stopped and the compared token start right acquisition frame is transmitted. This means that when the communication node stops sending the token start right acquisition frame, the communication node cannot acquire the token start right. Further, when the token start right acquisition processing unit 21 returns the token start right acquisition frame, it means that the token start right acquisition frame has been acquired, and stops sending the token start right acquisition frame.

  When the token start processing unit 22 acquires the token start right, the token start processing unit 22 transmits a token start notification frame indicating that the token frame transmission is started to all communication nodes on the network (ring) at predetermined time intervals. To do. Also, when the token start notification frame sent by itself circulates around the ring and returns, the token start notification frame is discarded, and the token start notification frame is stopped and communication is performed using the token passing method. Send the token frame.

  FIGS. 4-1 to 4-15 are diagrams schematically illustrating an example of a procedure of token start right acquisition processing in the ring communication system. First, when the ring establishment confirmation process and the network configuration information creation process are completed, as shown in FIG. 4A, the communication processing units 17-1 to 17-1 of the stations (1 station to 4 stations) 10-1 to 10-4. The token start right acquisition processing unit 21-4 sends out the first token start right acquisition frames 301-1 to 304-1 in which the unique information of each station is embedded at predetermined time intervals. However, at this time, the first token start right acquisition frame 301-1 transmitted from the first station 10-1 has disappeared for some reason on the transmission path between the first station 10-1 and the second station 10-2. To do.

  Next, as shown in FIG. 4B, when the communication node that has transmitted the token start right acquisition frame receives the token start right acquisition frame from another station, the token start right acquisition processing unit 21 of the communication processing unit 17. Compares the unique information of the own communication node with the unique information of the transmission source communication node in the received token start right acquisition frame. In this example, it is assumed that the unique information of each station has a magnitude relationship of 1 station <2 stations <3 stations <4 stations.

  Token start of the communication processing units 17-3 and 17-4 of the third station 10-3 and the fourth station 10-4 that have received the token start right acquisition frame from the communication node having unique information smaller than the unique information of the own station The right acquisition processing unit 21 transfers the received first token start right acquisition frames 302-1 and 303-1 respectively, and stops transmission of the token start right acquisition frame from the own station. In other words, both the third station 10-3 and the fourth station 10-4 are unable to acquire the right to start a token and have lost.

  The token start right acquisition processing unit 21 of the communication processing unit 17-1 of the first station 10-1 that has received the token start right acquisition frame from the communication node having the unique information larger than the unique information of the own station receives The first token start right acquisition frame 304-1 issued by the four stations 10-4 is discarded, and the transmission processing of the token start right acquisition frame from the own station is continued.

  Note that the two stations 10-2 that did not receive the first token start right acquisition frame 301-1 issued by the first station 10-1 that disappeared on the transmission path cannot compare the size of the specific information. No processing is performed.

  Next, as shown in FIG. 4-3, when a predetermined time has elapsed, the communication node that has not lost on the network sends out a token start right acquisition frame again, and the losing communication node receives other received communication nodes. Transfer the token start right acquisition frame of the communication node. Here, since the first station 10-1 and the second station 10-2 belong to the communication node that has not lost, the second token start right acquisition frames 301-2 and 302-2 are transmitted. Further, since the third station 10-3 and the fourth station 10-4 are losing communication nodes, the first token start right acquisition frames 302-1 issued by the second station 10-2 and the third station 10-3, respectively. , 303-1.

  Next, as shown in FIG. 4-4, when each communication node receives the next token-start-right acquisition frame, the unique information is compared in size as described with reference to FIG. Here, the second station 10-2 is newly lost. As a result, as shown in FIG. 4-5, the # 1 station 10-1 discards the first token start right acquisition frame 303-1 issued by the # 3 station 10-3, and the third token start right The acquisition frame 301-3 is transmitted, and the second station 10-2, the third station 10-3, and the fourth station 10-4 are the second issued by the first station 10-1, the second station 10-2, and the second station 10-2, respectively. The token start right acquisition frame 301-2, the second token start right acquisition frame 302-2, and the first token start right acquisition frame 302-1 are transferred.

  Here, since the token start right acquisition frame is continuously transmitted at a predetermined time interval, even if the token start right acquisition frame is accidentally lost for some reason, the subsequent token start right acquisition frame is Cycle around the ring. As a result, the second station 10-2 that has not received the first token start right acquisition frame 301-1 previously issued by the first station 10-1 also acquires the token start right issued by the first station 10-1 thereafter. The frame 301-2 is received, and the size comparison between the unique information of the own communication node and the unique information of the transmission source communication node of the token start right acquisition frame can be performed.

  Further, each time the communication node (3 station 10-3, 4 station 10-4) that has stopped transmitting the token start right acquisition frame receives the token start right acquisition frame from another communication node, the communication node own information And the unique information of the transmission source station of the token start right acquisition frame are compared, and it is determined whether the received token start right acquisition frame is discarded or transferred.

  Similarly, as shown in FIG. 4-6 to FIG. 4-9, each time the token start right acquisition frame circulates and is received at each station, the unique information of the own communication node and the received token start right acquisition frame The size is compared with the unique information of the source station. Then, the second station 10-2, the third station 10-3, and the fourth station 10-4 that have received the token start right acquisition frame having unique information smaller than the unique information of the own station transfer the token start right acquisition frame, The first station 10-1 that has received the token start right acquisition frame having unique information larger than the unique information of its own station discards the token start right acquisition frame and issues a new token start right acquisition frame. That is, as the token start right acquisition frame circulates on the ring, the communication nodes that transmit the token start right acquisition frame are limited to only the communication node (one station 10-1) with the smallest unique information.

  Thereafter, as shown in FIG. 4-10, the token start right acquisition processing unit 21 of the communication processing unit 17-1 of the first station 10-1 having the smallest unique information receives the second token start right issued by the own station. When the acquisition frame 301-2 is received, transmission of the token start right acquisition frame after that time is stopped. In addition, by acquiring the token start right acquisition frame 301-2 issued by the own station, the first station 10-1 becomes a communication node that has acquired (wins) the token start right. Become.

  Next, as shown in FIG. 4-11, the token start processing unit 22 of the communication processing unit 17-1 of the first station 10-1 that has acquired the token start right sends the token start notification frame 311-1 to a predetermined time interval. Start sending out. Thereafter, as shown in FIGS. 4-12 to 4-14, the communication nodes (2 station 10-2, 3 station 10-3) that have received the token start notification frames 311-1 to 311-2 receive the tokens. The start notification frames 311-1 to 311-2 are transferred and prepared for token passing. Also, the # 1 station 10-1 discards the token start right acquisition frame 301-4 issued by itself.

  Thereafter, as shown in FIG. 4-15, the token start processing unit 22 of the communication processing unit 17-1 of the first station 10-1 sending out the token start notification frame circulates the ring and sends a token to the local station. When the start notification frame 311-1 returns, it is confirmed that all token start right acquisition frames have been lost (discarded) on the ring, and token passing is started. This completes the token issuing method in the Ethernet (registered trademark) -based ring communication system.

  The above description is an example, and for example, a token start right may be given to a communication node to which unique information having the largest value among communication nodes 10-1 to 10-4 constituting the network is assigned. .

  Now, the reason why the first station 10-1 that has become the token issuing station in the above description outputs the token start notification frame 311 without immediately issuing a token will be described. Each of the communication nodes 10-1 to 10-4 is equipped with a frame monitoring function (not shown) for monitoring a network frame, as shown in an embodiment described later. Then, by this frame monitoring function, when a timeout occurs, it is determined that the token frame has disappeared, and transmission of the token start right acquisition frame is started. At this time, communication nodes other than the communication node 10 that has issued the token start right acquisition frame switch from the normal communication state (token passing state) to the token start right acquisition processing state by receiving the token start right acquisition frame. In the same manner as described above, the token issuing authority is determined again. Here, in the step of determining the token issuing authority without issuing the token start notification frame, if the communication node 10 loses without acquiring the token start right, it immediately enters a state ready for token passing. If the process of determining the token issuing authority is not completed and the token issuing authority is not yet determined, a token start right acquisition frame issued by another communication node 10 is received, and the token start right is acquired. Transition to the processing state. Then, the losing communication node 10 starts sending out the token start right acquisition frame again, and the process of determining the token issuing station will not converge. Therefore, in order to prevent such a situation, the token start notification frame 311 is received without setting so that the losing communication node 10 is switched to the token passing state during the process of determining the token issuing station. After that, we are preparing for the token passing state.

  According to the first embodiment, even in a multi-vendor environment in which a ring is configured by communication nodes 10 manufactured by different vendors, based on the size of unique information uniquely assigned to the communication node 10, This has the effect that the token issuing authority that issues the token frame is uniquely determined. In addition, by using the MAC address as the unique information, unlike the unique information set by the user, there is no duplication, so that there is an effect that one token issuing station is always uniquely determined.

  Further, each communication node 10 issues a token start right acquisition frame at a predetermined time interval until it is determined that the token start right cannot be acquired. Even if disappears, it is possible to make a determination for acquiring a token start right using a token start right acquisition frame issued later. Further, unnecessary frames are eliminated on the network, and it is possible to prevent erroneous recognition of received frames.

Embodiment 2. FIG.
In the second embodiment, a token issuing process when a token frame is lost due to some uncertain factor will be described.

  FIG. 5 is a block diagram schematically showing a functional configuration of the communication node according to the second embodiment. The communication processing unit 17 of the communication node according to the second embodiment further includes a frame monitoring unit 31. The frame monitoring unit 31 monitors a frame that flows on the ring when the ring is in a normal communication state, and a state in which a token frame and other frames do not flow on the ring for a predetermined time continues. It is determined that the token frame has been lost.

  When the frame monitoring unit 31 determines that the token frame has disappeared, the token start right acquisition processing unit 21 starts sending out the token start right acquisition frame. However, when a communication node in the token passing state receives a token start right acquisition frame from another communication node, the unique information of the transmission source communication node of the token start right acquisition frame is Only when it is larger, the received token start right acquisition frame is discarded, and processing for sending out the token start right acquisition frame from the own communication node is started. Other configurations are the same as those described above, and the same components as those described above are denoted by the same reference numerals and description thereof is omitted.

  FIGS. 6-1 to 6-17 are diagrams schematically illustrating an example of a procedure of a token start right acquisition process in the ring communication system. First, it is assumed that the token frame is lost due to some uncertain factor from the normal token ring communication state. After that, as shown in FIG. 6A, when the frame monitoring unit 31 of the communication processing unit 17-3 of the third station 10-3 first detects the disappearance of the token frame, the token start right acquisition processing unit 21 The token start right acquisition frame 303-1 is started to be transmitted at a predetermined time interval.

  Thereafter, as shown in FIG. 6B, when the 4th station 10-4 during token passing receives the token start right acquisition frame 303-1 issued by the 3rd station 10-3, the communication processing unit 17-4 The token start right acquisition processing unit 21 compares the unique information of the own station with the unique information of the transmission source communication node (3 station 10-3) in the token start right acquisition frame 303-1. Here, as in the first embodiment, it is assumed that the unique information of each station has a magnitude relationship of 1 station <2 stations <3 stations <4 stations. As a result, the 4th station 10-4 has received the token start right acquisition frame from the communication node having the unique information smaller than the own information of the own station, and therefore lost the token start right and lost. It becomes a state. Then, as shown in FIG. 6-3, the fourth station 10-4 stops the token passing and transfers the received token start right acquisition frame 303-1 as it is.

  On the other hand, as shown in FIGS. 6-4 to 6-5, the token start right acquisition frame 303-1 next reaches the first station 10-1. Similarly, the first station 10-1 compares the unique information of the transmission source communication node (third station 10-3) of the token start right acquisition frame with the unique information of the own station. The token start right acquisition processing unit 21 of the communication processing unit 17-1 of the first station 10-1 that has received the token start right acquisition frame from the communication node having unique information larger than the unique information of the own station performs token passing. At the same time, the received token start right acquisition frame 303-1 of the third station 10-3 is discarded, and the token start right acquisition frame 301-1 is transmitted from the own station at a predetermined time interval. As shown in FIGS. 6-6 to 6-7, the token start right acquisition frame circulates, and the first station 10-1, 2 10-2, and 4 station 10 that receive the next token start right acquisition frame are received. -4 performs the same processing. In this process, the second station 10-2 that has received the token start right acquisition frame 301-1 having unique information smaller than the unique information of the own station is also in a losing state where the token start right cannot be obtained.

  After that, as shown in FIGS. 6-8 to 6-9, the third station 10-3 that first sent out the token start right acquisition frame 303-1 transmits the token start right acquisition frame 301 from the first station 10-1. -1 is received, the token start right acquisition processing unit 21 of the communication processing unit 17-3 receives the unique information of the local station and the transmission source communication node (1 station 10-1) in the token start right acquisition frame 301-1. Compare with the specific information of. Here, since the # 3 station 10-3 has received the token start right acquisition frame 301-1 from the # 1 station 10-1 having unique information smaller than the unique information of the own station, the third station 10-3 can obtain the token start right. It will be in a losing state. Then, the received token start right acquisition frame 301-1 of the first station 10-1 is transferred, and the transmission process of the token start right acquisition frame from the own station is stopped.

  At this time, the communication node (1 station 10-1) that has received the token start right acquisition frame from the communication node having the unique information larger than the unique information of the own station also receives the received token start right acquisition frame. Discard and continue to transmit the token start right acquisition frame from its own communication node.

  Next, as shown in FIGS. 6-10 to 6-11, as the token start right acquisition frames 301-1 and 301-2 circulate on the ring, the communication node that transmits the token start right acquisition frame It is limited only to the communication node (one station 10-1) with the smallest specific information.

  After that, as shown in FIG. 6-12, the token start right acquisition processing unit 21 of the communication processing unit 17-1 of the first station 10-1 having the smallest unique information receives the token start right acquisition frame 303 issued by the own station. When -1 is received first, the transmission of the token start right acquisition frame after that point is stopped. Further, by acquiring the token start right acquisition frame 303-1 issued by the own station, the first station 10-1 becomes a communication node that has acquired (wins) the token start right, and in the subsequent processing, Become.

  Next, as shown in FIG. 6-13, the token start processing unit 22 of the communication processing unit 17-1 of the first station 10-1 that has acquired the token start right transmits the token start notification frame 311-1 at a predetermined time interval. Start sending out. Thereafter, as shown in FIGS. 6-14 to 6-17, the second station 10-2 to the fourth station 10-4 that have received the token start notification frames 311-1 to 311-4 receive the token start notification frame 311. -1 to 311-4 are transferred and prepared for token passing. The first station 10-1 discards the token start right acquisition frame 301-2 issued by itself.

  Thereafter, as shown in FIG. 6-17, the token start processing unit 22 of the communication processing unit 17-1 of the first station 10-1 sending out the token start notification frames 311-1 to 311-4 When the token start notification frame 311-1 is returned to, it is confirmed that all the token start right acquisition frames have been lost (discarded) on the ring, and token passing is started. This completes the token issuing method.

  The above description is an example, and for example, a token start right may be given to a communication node to which unique information having the largest value among communication nodes 10-1 to 10-4 constituting the network is assigned. .

  According to the second embodiment, all the communication nodes immediately detect the disappearance of the token frame, and the detected communication node shifts from the token passing state to the token start right acquisition state. It is possible to resume. Further, unnecessary frames are eliminated on the network, and it is possible to prevent erroneous recognition of received frames.

Embodiment 3 FIG.
In the third embodiment, a case where communication is performed using a token passing system in an Ethernet (registered trademark) -based ring communication system will be described.

  FIG. 7 is a block diagram schematically showing a functional configuration of the communication node according to the third embodiment. The communication processing unit 17 of the communication node 10 includes a communication right acquisition processing unit 41, a logical ring state control unit 42, and a data frame communication processing unit 43. In addition, the same code | symbol is attached | subjected to the component same as the description mentioned above, and the description is abbreviate | omitted.

  The communication right acquisition processing unit 41 obtains a token right by acquiring a token frame flowing on the ring and receives a token indicating that the token frame has been acquired when the communication node wants to transmit data. A completion notification frame (hereinafter referred to as a token Ack frame) is transmitted to the communication node that has released the token frame. Further, the communication right acquisition processing unit 41 releases the token frame when the data frame communication processing unit 43 finishes transmitting the data frame.

  When the communication right is acquired by the communication right acquisition processing unit 41, the logical ring state control unit 42 logically disconnects the ring in the own communication node and transfers all frames received by the own communication node. State in which the communication mode is discarded without being transmitted, and when a token Ack frame is received from another communication node, the logical ring is terminated and the repeat mode in which all frames received by the own communication node are transferred. The control which isolates is performed.

  When the communication right is acquired, the data frame communication processing unit 43 transmits data to be transmitted as a data frame, and the communication node transmits it. The structure of the data frame communicated at this time is the same as that of a normal Ethernet (registered trademark) frame, and includes a destination MAC address and a source MAC address. Further, the data frame communication processing unit 43 performs a process of receiving a data frame addressed to the own communication node from another communication node. Note that the data frame communication processing unit 43 discards all received frames without forwarding when the own communication node is in the transmission mode, and receives all received frames when the own communication node is in the repeat mode. Forward frames.

  FIGS. 8-1 to 8-5 are diagrams illustrating an example of a communication processing procedure in the token passing system in the Ethernet (registered trademark) -based ring communication system. Here, a case where a data frame transmitted as a communication message is broadcast and destined for all communication nodes on the ring will be described as an example.

  First, the # 1 station 10-1 that has already acquired the token frame 320 enters the transmission mode state in which the ring within the own station is logically disconnected by the logical ring state control unit 42 of the communication processing unit 17-1. Yes, transmission of a communication message (hereinafter referred to as a data frame) 321 by the data frame communication processing unit 43 and termination processing (discard processing) for the data frame 321 issued by the own station are performed. When the transmission of all data frames 321 by the data frame communication processing unit 43 is completed, the communication right acquisition processing unit 41 transmits a token frame 320. Even after transmitting the token frame 320, the first station 10-1 remains in the transmission mode state (FIG. 8-1). As shown in the second station 10-2 to the fourth station 10-4 in FIG. 8-1, a solid line extends from the A port 11-2 to 11-4 to the B port 14-2 to 14-4. The state indicates the repeat mode, and the state where the solid line does not extend from the A port 11-1 to the B port 14-1 like the first station 10-1 indicates the transmission mode in which the ring is logically disconnected. Yes.

  Next, the second station 10-2 that has received the token frame 320 terminates (acquires) the token frame 320 by the communication right acquisition processing unit 41 of the communication processing unit 17-2. Since the communication right acquisition processing unit 41 receives the token frame 320 from the first station 10-1, the communication right acquisition processing unit 41 transmits the talk Ack frame 331 to the first station 10-1 that is a token release station. Further, the logical ring state control unit 42 logically disconnects the ring in the own station and transitions to the transmission mode. Then, the data frame communication processing unit 43 sends out the data frame 322 and terminates the data frame 322 issued by the own station. When the transmission of all data frames 322 by the data frame communication processing unit 43 is completed, the communication right acquisition processing unit 41 transmits a token frame 320. Even after transmitting the token frame 320, the second station 10-2 remains in the transmission mode state (FIG. 8-2).

  Thereafter, the frame circulates and the # 1 station 10-1 receives the data frame 321 issued by itself. At this time, since the first station 10-1 is in the transmission mode, the data frame communication processing unit 43 discards the received data frame 321 (FIG. 8-3).

  Subsequently, the # 1 station 10-1 receives the token Ack frame 331 addressed to itself. At this time, since the first station 10-1 is in the transmission mode, the data frame communication processing unit 43 discards the received token Ack frame 331, and the logical ring state control unit 42 receives the token Ack frame 331. As a result, the state of the local station is changed from the transmission mode to the repeat mode in which the logical ring disconnection is completed (FIG. 8-4). Thereafter, all frames received from the A port 11-1 of the first station 10-1 are transferred (FIG. 8-5). As each station performs the processes shown in FIGS. 8-1 to 8-5, the token passing communication is performed.

  According to the third embodiment, for each communication node 10, the communication node 10 that has acquired the communication right has acquired the transmission mode for logically disconnecting the ring within the communication node 10 and the communication right. Since there is a repeat mode for transferring the received frame to the non-communication node 10, the communication node 10 that has acquired the communication right discards the frame originating from the own communication node 10 without causing fragmentation. It has the effect of being able to.

  In addition, since the communication node 10 that has acquired the communication right by acquiring the token frame transmits the token Ack frame to the communication node that has transmitted the token frame, the transmission mode is changed from the transmission mode to the repeat mode. It has the effect that it can switch to. As a result, the frame issued by the communication node 10 and the token Ack frame can be removed from the ring, and unnecessary frames can be prevented from staying on the ring.

Embodiment 4 FIG.
In the third embodiment, a communication node that releases a token frame and is in a transmission mode state (hereinafter referred to as a token release communication node) receives a communication from the communication node that acquired the token frame (hereinafter referred to as a token acquisition communication node). By receiving the token Ack frame addressed to the own station, the state is changed from the transmission mode to the repeat mode. However, in this case, the token Ack frame transmitted from the token acquisition communication node may be lost for some reason. In the fourth embodiment, a communication method using the token passing method when the token Ack frame disappears before reaching the token release communication node will be described.

  The functional configuration of the communication node in the fourth embodiment is the same as that in FIG. 7 of the third embodiment. However, in the fourth embodiment, when the logical ring state control unit 42 of the communication processing unit 17 in FIG. 7 is in the transmission mode state, before receiving the token Ack frame addressed to its own communication node, When the data frame transmitted by the communication node (token acquisition communication node) is received, the communication node (token acquisition communication node) further has a function of transitioning to the repeat mode.

  FIG. 9A to FIG. 9C are diagrams illustrating an example of a communication processing procedure in the token passing system in the Ethernet (registered trademark) -based ring communication system. First, as described with reference to FIGS. 8A to 8B of the third embodiment, the second station 10-2 transmits the data frame 321 and releases the token frame 320, and the first station 10-1 releases the token frame 320. 320 is acquired, and a token Ack frame 331 addressed to the first station 10-1, which is a token release communication node, and a data frame 322 are transmitted on the ring.

  Thereafter, the frame circulates and the # 1 station 10-1 receives the data frame 321 issued by itself. At this time, since the first station 10-1 is in the transmission mode, the data frame communication processing unit 43 discards the received data frame 321. At this time, it is assumed that the token Ack frame 331 has disappeared due to an uncertain factor on the ring between the 4th station 10-4 and the 1st station 10-1 (FIG. 9-1).

  Thereafter, the first station 10-1 receives the data frame 322 issued by the other station (second station 10-2) without receiving the token Ack frame 331 addressed to itself (FIG. 9-2). The logical ring state control unit 42 of the communication processing unit 17-1 of the first station 10-1 detects that the data frame 322 of the other station has been received without receiving the token Ack frame 331, and transmits the state of the own station. The mode is switched from the repeat mode to the logical ring in the first station 10-1. As a result, the data frame communication processing unit 43 of the communication processing unit 17-1 of the first station 10-1 transfers the received data frame 322 from the second station 10-2 as it is, and also transfers all the frames received thereafter. (FIG. 9-3).

  According to the fourth embodiment, using the fact that the data frame arrives after the token Ack frame, even if the token Ack frame disappears, the token release communication node is changed from the transmission mode to the repeat mode. Can be transitioned. As a result, even when the token Ack frame is lost, there is an effect that a subsequent frame is not inadvertently discarded.

Embodiment 5 FIG.
In the fourth embodiment, the token release communication node shifts the state from the transmission mode to the repeat mode by receiving the data frame received thereafter even when the token Ack frame addressed to itself is lost. I was doing. However, in this case, in addition to the token Ack frame transmitted from the token acquisition communication node, the data frame may be lost for some reason. In the fifth embodiment, a token passing communication method when a token Ack frame and a data frame issued by a token acquisition communication node are lost before reaching the token release communication node will be described.

  The functional configuration of the communication node in the fifth embodiment is the same as that in FIG. 7 of the third embodiment. However, in the fifth embodiment, the logical ring state control unit 42 of the communication processing unit 17 shown in FIG. 7 is in the transmission mode state before receiving the token Ack frame addressed to the own communication node. When the data frame transmitted by the acquisition communication node) is received, or before receiving the token Ack frame addressed to the own communication node and the data frame issued by another communication node (token acquisition communication node), another communication node When the issued token Ack frame addressed to the other communication node is received, a function of shifting to the repeat mode is further provided.

  FIG. 10A to FIG. 10B are diagrams illustrating an example of a communication processing procedure in the token passing system in the Ethernet (registered trademark) -based ring communication system. First, as described with reference to FIGS. 8A to 8B of the third embodiment, the second station 10-2 transmits the data frame 321 and releases the token frame 320, and the first station 10-1 releases the token frame 320. 320, the token Ack frame 331 addressed to the first station 10-1, which is the token release communication node, and the data frame 322 are transmitted on the ring, and then the token frame 320 is released. Thereafter, as described with reference to FIG. 9-1 of the fourth embodiment, when the frame circulates and the first station 10-1 receives the data frame 321 issued by itself, the first station 10-1 discards the data frame 321. At this time, it is assumed that the third station 10-3 acquires the token frame 320, and the token Ack frame 331 is lost due to an uncertain factor on the ring between the fourth station 10-4 and the first station 10-1.

  Further, although the frame circulates, it is assumed that the data frame 322 issued by the second station 10-2 is also lost on the transmission path between the fourth station 10-4 and the first station 10-1. On the other hand, the communication right acquisition processing unit 41 of the third station 10-3 that acquired the token frame 320 transmits a token Ack frame 332 that is destined for the second station 10-2 that is the transmission source of the token frame 320. Thereafter, the data frame communication processing unit 43 of the third station 10-3 transmits the data frame 323 (FIG. 10-1).

  Thereafter, the first station 10-1 receives the token Ack frame 331 addressed to itself and the data frame 322 that should have been issued by the other station (second station 10-2). The token Ack frame 332 addressed to the station 10-2 is received. The logical ring state control unit 42 of the communication processing unit 17-1 of the first station 10-1 does not receive the token Ack frame 331 addressed to itself and the data frame 322 issued by the second station 10-2. -3 issues the token Ack frame 332 addressed to the second station 10-2 and switches the state of the own station from the transmission mode to the repeat mode. Terminate cutting. Thereby, the data frame communication processing unit 43 of the communication processing unit 17-1 of the first station 10-1 transfers the received token Ack frame 332 addressed to the second station 10-2 issued by the third station 10-3 as it is. Thereafter, all frames received thereafter are also transferred (FIG. 10-2).

  According to the fifth embodiment, a data frame (data frame) arrives after the token Ack frame, and a token Ack frame addressed to another station issued by another communication node arrives after the data frame. Even when the token Ack frame or the data frame is lost, the token release communication node can change the state from the transmission mode to the repeat mode. As a result, even when the token Ack frame or the data frame is lost, there is an effect that a subsequent frame is not inadvertently discarded.

Embodiment 6 FIG.
In the fifth embodiment, even when the token Ack frame addressed to the own communication node and the subsequent data frame are lost, the token release communication node receives the token Ack addressed to the other communication node issued by the other station received thereafter. The state is changed from the transmission mode to the repeat mode by receiving the frame. In the sixth embodiment, the token Ack frame and data frame addressed to other communication nodes issued by other communication nodes are also lost, and the communication node that should have received the token Ack frame addressed to the own communication node. However, a description will be given of a token passing communication method when a token frame is received without receiving a token Ack frame or a data frame.

  The functional configuration of the communication node in the sixth embodiment is the same as that in FIG. 7 of the third embodiment. However, in the sixth embodiment, the communication right acquisition processing unit 41 of the communication processing unit 17 in FIG. 7 is not limited to the token Ack frame addressed to the own communication node in the transmission mode, but also the data frame issued by another communication node. When receiving a token frame again without receiving a token Ack frame addressed to another communication node, the token frame is acquired again, and a function of transmitting the token Ack frame to the token frame issuer communication node is further provided. The data frame communication processing unit 43 further has a function of transmitting again the data frame issued by the self communication node received before receiving the token Ack frame addressed to the self communication node.

  11-1 to 11-5 are diagrams illustrating an example of a communication processing procedure using a token passing system in an Ethernet (registered trademark) -based ring communication system. First, as described with reference to FIGS. 8A to 8B of the third embodiment, the second station 10-2 transmits the data frame 321 and releases the token frame 320, and the first station 10-1 releases the token frame 320. 320 is acquired, and after a token Ack frame 331 addressed to the first station 10-1, which is a token release communication node, and a data frame 322 are transmitted on the ring, the token frame is released.

  Thereafter, the frame circulates and the # 1 station 10-1 receives the data frame 321 issued by itself. At this time, since the first station 10-1 is in the transmission mode, the data frame communication processing unit 43 discards the received data frame 321. At this time, the third station 10-3 acquires the token frame 320 and acquires the communication right, and the first station 10-1 due to an uncertain factor on the ring between the fourth station 10-4 and the first station 10-1. It is assumed that the addressed token Ack frame 331 has disappeared (FIG. 11-1).

  Furthermore, although the frame circulates, the data frame 322 issued by the second station 10-2 and the token Ack frame 332 issued to the second station 10-2 when the third station 10-3 acquires the token frame 320 are also obtained. It is assumed that it has disappeared due to an uncertain factor on the ring between the 4th station 10-4 and the 1st station 10-1. At this time, the third station 10-3 transmits the data frame 323 and then releases the token frame 320 (FIG. 11-2).

  Further, the frame circulates, and the fourth station 10-4 acquires the token frame 320 and acquires the communication right. The data frame 323 issued by the third station 10-3 and the token Ack frame 333 issued to the third station 10-3 when the fourth station 10-4 issued the token frame 320 are also the four station 10-4. It is assumed that it has disappeared due to an uncertain factor on the ring between the stations 10-1 (FIG. 11-3).

  Next, the fourth station 10-4 transmits the data frame 324 to release the token frame 320. At this time, it is assumed that the data frame 324 issued by the fourth station 10-4 is also lost due to an uncertain factor on the ring between the fourth station 10-4 and the first station 10-1 (FIG. 11-4). Thereafter, the # 1 station 10-1 receives the token frame 320 released by the # 4 station 10-4. The communication right acquisition processing unit 41 of the first station 10-1 receives the data frame 321 previously issued by the own station, and then receives the token Ack frame 331 addressed to the own communication node, the data frames 322 to 324 of other stations, and the other stations. Since the token frame 320 is received again without receiving the addressed token Ack frames 332 and 333 at all, the received token frame 320 is acquired and a communication right is acquired. Next, the communication right acquisition processing unit 41 transmits a token Ack frame 334 to the fourth station 10-4, which is a token release communication node (FIG. 11-5). The data frame communication processing unit 43 releases the token frame 320 after transmitting the data frame 321 transmitted in FIG. 8A again. The logical ring state control unit 42 is not in the transmission mode when the first station 10-1 receives the token frame 320, and therefore does not switch the state.

  After this, the communication nodes (3 station 10-3 and 4 station 10-4) after the 2 station 10-2 will receive the 4 station 10-4 transmitted by the 1 station 10-1 unless the frame disappears. Using the addressed token Ack frame 334, the state is switched from the transmission mode to the repeat mode as described in the fifth embodiment.

  According to the sixth embodiment, when a communication node that should have received a token Ack frame addressed to itself receives a token frame without receiving a token Ack frame or a data frame, the token frame is acquired. In addition, since the same data frame as the received data frame is transmitted before receiving the token Ack frame addressed to the own station, there is an effect that the data can be surely delivered to the destination communication node.

Embodiment 7 FIG.
In the seventh embodiment, a token frame regeneration process when a token frame is lost due to an indeterminate factor during communication using the token passing system will be described.

  FIG. 12 is a block diagram schematically showing a functional configuration of the communication node according to the seventh embodiment. This communication node 10 has a configuration combining FIG. 5 of the second embodiment and FIG. 7 of the third embodiment. That is, the communication processing unit 17 of the communication node 10 includes a token start right acquisition processing unit 21 that performs a token start right acquisition process, and the communication node that has acquired the token start right receives tokens from all communication nodes on the ring. The token start processing unit 22 for performing notification for starting communication in the passing method, the frame monitoring unit 31 for monitoring the token frame, the token Ack frame, and the data frame flowing in the ring, and communication in the token passing method are started. A communication right acquisition processing unit 41 that performs processing for acquiring a communication right in a state, and a logical that performs control for switching a ring in the communication node between a logically disconnected state and a logically connected state. A ring state control unit 42 and a data frame communication processing unit 43 that performs data frame communication processing are provided.

  Here, the frame monitoring unit 31 monitors all the frames including the token frame, the token Ack frame, and the data frame flowing on the ring, and detects that the token has been lost when the frame does not flow on the ring for a predetermined time. To detect.

  FIGS. 13A to 13D are schematic diagrams illustrating an example of a procedure of token frame reproduction processing due to loss of a token frame. In these figures, black circles attached to the A ports 11-1 to 11-4 of the stations 10-1 to 10-4 are frame monitoring units provided in the communication processing units 17-1 to 17-4. 31-1 to 31-4 are shown. First, the # 1 station 10-1 acquires the token frame 320, transmits the data frame 321, and then releases the token frame 320. Thereafter, it is assumed that the token frame 320 is lost on the ring between the first station 10-1 and the second station 10-2 due to an uncertain factor (FIG. 13-1). At this time, only the first station 10-1 that transmitted the data frame 321 is in the transmission mode, and the second station 10-2 to the fourth station 10-4 are in the repeat mode.

  When the data frame 321 issued by the first station 10-1 circulates and is received again after returning to the first station 10-1, the first station 10-1 is in the transmission mode, so the received data frame 321 is discarded. (FIG. 13-2). In addition, the frame monitoring unit 31-2 of the second station 10-2 detects that a frame is not received for a predetermined time or longer after the data frame 321 is received and transferred (the frame does not flow on the ring). (FIG. 13-3). That is, the frame monitoring unit 31-2 detects that the token frame 320 has disappeared. Accordingly, the token start right acquisition processing unit 21 of the communication processing unit 17-2 of the second station 10-2 performs the token start right acquisition processing described in the second embodiment and regenerates the token frame 320. Is started (FIG. 13-4). Here, a state is shown in which the second station 10-2 sends out the token start right acquisition frame 302-1 at a predetermined time interval.

  In FIG. 13C, the second station 10-2 first detects that the token frame 320 has disappeared, among the communication nodes located downstream of the position where the token frame 320 has disappeared. This is because the communication node is closest to the position where is lost. In this case, it is assumed that the time (timer value) for determining that the token frame 320 is lost is constant in all the communication nodes 10-1 to 10-4 on the ring.

  According to the seventh embodiment, even when the token frame is lost during the token passing communication, the loss can be detected, so that the token frame can be quickly regenerated. it can. As a result, the token frame can be automatically recovered from being lost.

  As described above, the Ethernet (registered trademark) -based ring communication system according to the present invention is useful for a network including a plurality of communication nodes.

10, 10-1 to 10-4 Communication node 11, 11-1 to 11-4 A port 12, 12-1 to 12-4 B port 17, 17-1 to 17-4 Communication processing unit 21 Token start right acquisition Processing unit 22 Token start processing unit 31 Frame monitoring unit 41 Communication right acquisition processing unit 42 Logical ring state control unit 43 Data frame communication processing unit

Claims (6)

A communication node constituting a communication system in which a plurality of communication nodes connected by Ethernet (registered trademark) are connected in a ring shape,
When a token frame is acquired and a communication right is acquired, a token reception completion notification frame destined for the token frame transmission source communication node is transmitted, and when the data frame transmission process is completed, the token frame is released. Processing means;
When the communication right is acquired, when the transmission mode for disconnecting the logical connection in the own communication node and the token reception completion notification frame addressed to the own communication node are received, the disconnection of the logical connection in the own communication node is terminated. A logical ring state control means for switching the state between repeat mode;
Data frame communication processing means for transmitting and receiving data frames;
With
The data frame communication processing means discards all received frames when in the transmission mode, and forwards the received frames when in the repeat mode.   When the logical ring state control means receives a token reception completion notification frame addressed to another communication node without receiving a token reception completion notification frame addressed to the own communication node, the logical ring state control means switches the state of the own communication node to a repeat mode. The communication node according to claim 1, wherein:   The communication node according to claim 2, wherein the data frame communication processing unit transfers a received frame after a token reception completion notification frame addressed to another communication node. A token ring communication method for performing communication by a token passing method in a communication system in which a plurality of communication nodes connected by Ethernet (registered trademark) are connected in a ring shape,
Acquiring a token frame and acquiring a communication right, a communication right acquisition step of transmitting a token reception completion notification frame addressed to the transmission source communication node of the token frame;
When acquiring the communication right, a transmission mode switching step of disconnecting the logical connection in the communication node and switching the communication node to the transmission mode;
A data frame transmission step of transmitting a data frame to a communication node of a desired destination;
A token frame releasing step of releasing the token frame when transmission processing of the data frame to be transmitted is completed;
Discards all frames received before receiving the token reception completion notification frame addressed to the local communication node and terminates the logical connection disconnection within the local communication node when receiving the token reception completion notification frame addressed to the local communication node Then, the own communication node is switched to the repeat mode, and a repeat mode switching step for transferring a frame received thereafter,
Including a token ring communication method.   In the repeat mode switching step, when the token reception completion notification frame addressed to the other communication node is received without receiving the token reception completion notification frame addressed to the own communication node, the state of the own communication node is switched to the repeat mode. The token ring communication method according to claim 4, wherein   6. The token ring communication method according to claim 5, wherein, in the repeat mode switching step, received frames after the received token reception completion notification frame addressed to the other communication node are transferred.

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