JP4906910B2 - Communication node and communication system ring establishment confirmation method - Google Patents

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 ring configuration method and a ring establishment method of the 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, written by Naoki Mizuma, "FDDI Technical Details-Construction of 100 Mbps LAN", 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. In the star topology, when a failure occurs in the repeater (hub), all communication nodes connected to the repeater become unable to communicate, or communication messages concentrate on the repeater and the repeater communicates. There was a problem of becoming a performance bottleneck. Furthermore, in the conventional Ethernet (registered trademark) topology, there is a problem that collision and congestion occur, and it is difficult to ensure punctuality.

  When the network is established, it is necessary to pass station information to communication nodes other than the own communication node existing on the network so that each communication node can recognize the network configuration. At this time, it is necessary for the station information transmission source to receive a response from another communication node to check whether the station information has been distributed to all communication nodes on the network, but the processing is complicated. There was also a problem.

  Further, although the FDDI described above exists as a ring topology, there is a problem that a network using the FDDI is not as widespread as a network using the Ethernet (registered trademark) at present. In addition, even if a network using Ethernet (registered trademark) is configured in a ring topology, there is a problem that the FDDI standard cannot be applied to Ethernet (registered trademark) as it is.

  The present invention has been made in view of the above, and to obtain a communication node used in an Ethernet (registered trademark) -based ring communication system in which communication nodes are connected by Ethernet (registered trademark) without using a repeater. With the goal. Another object of the present invention is to provide a communication node capable of easily configuring a ring that eliminates a failure when a failure is found in a ring topology network constructed with Ethernet (registered trademark), and a ring configuration method for a communication system. To do.

  It is another object of the present invention to provide a route establishment method in a ring communication system that defines a procedure necessary for performing communication between communication nodes in an Ethernet (registered trademark) -based ring communication system. Specifically, in an Ethernet (registered trademark) -based ring communication system, a communication node capable of confirming whether a path constituted by normal communication nodes is configured in a ring shape, and a ring establishment of the communication system The purpose is to obtain a confirmation method.

  Further, in an Ethernet (registered trademark) -based ring communication system, a communication node capable of easily confirming whether station information has been distributed to all communication nodes on the network after the ring is established, and a ring of the communication system It is also aimed to obtain an establishment confirmation method.

  In order 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 inputs a frame. When the first and second ports having an input unit and an output unit for outputting a frame and the first and second ports are normal, reception processing of a frame input from the input unit of the first port is performed. Then, when the frame is transmitted from the output unit of the second port and communication abnormality occurs with the adjacent communication node, the frame is input from the input unit of the port different from the port connected to the adjacent communication node. The received frame is received, loopback processing is performed to transmit the frame from the output unit of the same port as the input unit to which the frame is input, and other communication When the node performs the loopback processing, communication processing means for transmitting the frame from the output unit of the first port without performing reception processing of the frame input from the input unit of the second port; The communication processing means issues a ring establishment confirmation frame in which an issue time is embedded when power is turned on or when a self-communication node performs a loopback process to configure a new ring, and circulates the ring. When the ring establishment confirmation frame is received, a ring establishment confirmation frame issuing unit that stops issuing subsequent ring establishment confirmation frames, and the ring establishment that has been circulated around the ring, issued by the ring establishment confirmation frame issuing unit A frame cycle obtained by subtracting the issue time in the ring establishment confirmation frame from the time when the confirmation frame is received. Frame cyclic time calculating means for calculating time, and ring establishment determining means for determining whether or not to detect a ring establishment confirmation frame flowing in the ring for a period equal to or longer than the frame cyclic time after issuance of the ring establishment confirmation frame is stopped. It is characterized by providing.

  According to the present invention, by connecting communication nodes in a ring shape, it is not necessary to use a repeater necessary for a star topology or a bus topology connection form, so that all communication nodes cannot communicate due to a failure of the repeater. It is possible to eliminate such a situation, and it is possible to avoid a situation where communication messages concentrate on the repeater. Furthermore, since the number of repeaters can be reduced, there is an effect that the cost for system construction can be reduced.

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 diagram schematically showing a state in which a failure has occurred in the ring communication system. FIG. 4 is a diagram schematically showing a state where cables are erroneously connected in the ring configuration of the ring communication system. 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 ring establishment confirmation processing in the ring communication system (part 1). FIG. 6B is a diagram schematically illustrating an example of the procedure of the ring establishment confirmation process in the ring communication system (part 2). FIG. 6-3 is a diagram schematically illustrating an example of a procedure of ring establishment confirmation processing in the ring communication system (part 3). FIG. 6-4 is a diagram schematically illustrating an example of a procedure of ring establishment confirmation processing in the ring communication system (part 4). 6-5 is a figure which shows typically an example of the procedure of the ring establishment confirmation process in a ring-shaped communication system (the 5). FIG. 6-6 is a diagram schematically illustrating an example of a procedure of ring establishment confirmation processing in the ring communication system (part 6). FIG. 7 is a block diagram schematically showing a functional configuration of the communication node according to the third embodiment. FIG. 8A is a diagram schematically illustrating an example of a processing procedure for discarding the ring establishment confirmation frame (part 1). FIG. 8B is a diagram schematically illustrating an example of a processing procedure for discarding the ring establishment confirmation frame (part 2). FIG. 8C is a diagram schematically illustrating an example of a processing procedure for discarding the ring establishment confirmation frame (part 3). FIG. 8D is a diagram schematically illustrating an example of a processing procedure for discarding the ring establishment confirmation frame (part 4). FIG. 9A is a diagram illustrating an example of received frame information held by the four stations in the state of FIG. 8A. FIG. 9B is a diagram illustrating an example of the received frame information held by one station in the state illustrated in FIG. FIG. 10A is a schematic diagram illustrating an example of a procedure for confirming a connection state of a new ring formed after a loopback has occurred (part 1). FIG. 10B is a diagram schematically illustrating an example of a procedure for confirming a connection state of a new ring formed after the loopback has occurred (part 2). FIG. 10C is a diagram schematically illustrating an example of a procedure for confirming a connection state of a new ring formed after the loopback has occurred (part 3). FIG. 10-4 is a diagram schematically illustrating an example of a procedure for confirming the connection state of a new ring formed after the loopback has occurred (part 4). FIG. 10-5 is a diagram schematically illustrating an example of a procedure for checking the connection state of a new ring formed after the loopback has occurred (part 5). FIG. 11A is a diagram illustrating a problem state that may occur during the ring establishment confirmation process (part 1). FIG. 11B is a diagram illustrating a problematic state that may occur during the ring establishment confirmation process (part 2). FIG. 11C is a diagram illustrating a problematic state that may occur during the ring establishment confirmation process (part 3). FIG. 12 is a block diagram schematically showing a functional configuration of the communication node according to the fifth embodiment. FIG. 13A is a diagram schematically illustrating an example of a procedure of ring establishment confirmation processing when a new communication node joins in place of a disconnected communication node (part 1). FIG. 13-2 is a diagram schematically illustrating an example of a procedure of ring establishment confirmation processing when a new communication node enters in place of the disconnected communication node (part 2). FIG. 14A is a schematic diagram illustrating an example of a procedure for discarding a ring establishment confirmation frame that flows through the standby ring (part 1). FIG. 14B is a diagram schematically illustrating an example of a procedure for discarding the ring establishment confirmation frame that flows through the standby ring (part 2). FIG. 14C is a diagram schematically illustrating an example of a procedure for discarding the ring establishment confirmation frame that flows through the standby ring (part 3). FIG. 14-4 is a diagram schematically illustrating an example of a procedure for discarding the ring establishment confirmation frame that flows through the standby ring (part 4). FIG. 14-5 is a diagram schematically illustrating an example of a procedure for discarding the ring establishment confirmation frame that flows through the standby ring (part 5). FIG. 14-6 is a diagram schematically illustrating an example of a procedure for discarding the ring establishment confirmation frame that flows through the standby ring (part 6). FIG. 15 is a block diagram schematically showing a functional configuration of the communication node according to the seventh embodiment. FIG. 16A is a diagram schematically illustrating an example of a procedure of deleting a frame that is not related to the ring establishment confirmation process (part 1). FIG. 16B is a diagram schematically illustrating an example of a procedure of deleting a frame that is not related to the ring establishment confirmation process (part 2). FIG. 16C is a diagram schematically illustrating an example of a procedure of deleting a frame that is not related to the ring establishment confirmation processing (part 3). FIG. 16D is a diagram schematically illustrating an example of a procedure for deleting a frame not related to the ring establishment confirmation processing (part 4). FIG. 16-5 is a diagram schematically illustrating an example of a procedure of deleting a frame not related to the ring establishment confirmation processing (part 5). FIG. 17 is a diagram schematically showing a functional configuration of a communication node according to the eighth embodiment. FIG. 18A is a diagram schematically illustrating an example of a procedure of station information notification processing in the ring communication system (part 1). FIG. 18-2 is a diagram schematically showing an example of a procedure of station information notification processing in the ring communication system (part 2). FIG. 18-3 is a diagram schematically showing an example of a procedure of station information notification processing in the ring communication system (part 3). FIG. 18-4 is a diagram schematically showing an example of a procedure of station information notification processing in the ring communication system (part 4). FIG. 18-5 is a diagram schematically showing an example of a procedure of station information notification processing in the ring communication system (part 5). FIG. 18-6 is a diagram schematically showing an example of a procedure of station information notification processing in the ring communication system (part 6).

  Exemplary embodiments of a communication node and a communication system ring establishment confirmation 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 A port 11 corresponds to the first port in the claims, and the B port 14 also corresponds to the second port.

  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, a predetermined process is performed when necessary only for a frame output from the B port 14 at normal time, and what about a frame flowing from the B port 14 to the A port 11 in the communication node is determined. No processing is performed.

  Communication in a normal state in such an Ethernet (registered trademark) -based ring communication system uses a token frame for each communication node 10-1 to 10-4 to acquire a communication right in the normal ring 1. Done. The communication node 10 that wants to communicate acquires the communication right by receiving the token frame flowing in the normal ring 1 at the normal input unit 12 of the A port 11. The communication node 10 that has acquired the communication right transmits a data frame to be transmitted from the normal system output unit 16 of the B port 14 to the normal system ring 1 instead of the token frame. When the transmission of the data frame is completed, the token frame is returned from the normal system output unit 16 of the B port 14 to the normal system ring 1 and returned to a state where other communication nodes 10 can communicate.

  The above is the outline of the Ethernet (registered trademark) -based ring communication system common to the embodiments described below. 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. As long as 10 is configured to be connected in a ring shape with Ethernet (registered trademark), the following embodiment can be applied.

Embodiment 1 FIG.
In the first embodiment, a loopback process will be described in the case where a failure or an erroneous cable connection occurs in a part of the Ethernet (registered trademark) -based ring communication system shown in FIG.

<If a failure occurs>
FIG. 3 is a diagram schematically showing a state in which a failure has occurred in the ring communication system. As shown in FIG. 1, when normal communication using the normal ring 1 is performed in a network in which communication nodes 10-1 to 10-4 of 1 to 4 stations are connected in a ring shape, As shown in FIG. 3, it is assumed that a cable break occurs between the third station 10-3 and the fourth station 10-4. In this case, the communication processing unit 17 of the 4th station 10-4 does not receive a signal from the 3rd station 10-3 at the A port 11-4 of the 4th station 10-4 for a predetermined time or longer. It is determined that a failure has occurred in the cable between the port 10-3 and a loopback for connecting the standby system input unit and the normal system output unit of the B port 14-4 is performed. Here, since all the communication nodes (stations) 10-1 to 10-4 constituting the ring communication system have the same reference values for determining that a failure has occurred due to a time during which frames are not received, After the cable disconnection between -3 and 4 stations 10-4 occurs, it is the 4 stations 10-4 closest to the failure location of the normal ring 1 that first detects an abnormality. As a result, the four stations 10-4 perform the loopback process. Then, an abnormality notification signal indicating that a cable break has occurred between the third station 10-3 and the fourth station 10-4 is transmitted. When the communication processing unit 17 of the third station 10-3 receives the abnormality notification signal, the communication processing unit 17 knows that the cable disconnection between the third station 10-3 and the fourth station 10-4 has occurred, and In order not to output the frame, a loopback for connecting the normal system input unit of the A port 11-3 and the standby system output unit is performed.

  Through the above processing, the third station 10-3 and the fourth station 10-4 loop back the transmission line, and the standby ring 2 is used to connect the third station 10-3 and the fourth station 10-4 between the failure points. A new ring in which the cable is disconnected is reconfigured, and then the communication of each station is resumed. In the subsequent processing, the communication processing unit 17-3 of the third station 10-3 once reads the frame from the normal ring 1 received by the normal input unit of the A port 11-3, and performs predetermined processing. After performing, it outputs to the standby system ring 2 from the standby system output unit of the same A port 11-3, and the communication processing unit 17-4 of the 4 station 10-4 receives at the standby system input unit of the B port 14-4 A frame from the standby ring 2 is read once, a predetermined process is performed, and a process of transmitting the frame to the normal system output unit of the same B port 14 is performed.

  Note that FIG. 3 illustrates the loopback by taking the cable break between the third station 10-3 and the fourth station 10-4 as an example. Even when the (station) 10-1 to 10-4 fails, the ring is reconfigured in the same procedure.

<If the Ethernet (registered trademark) cable is connected incorrectly>
FIG. 4 is a diagram schematically showing a state where cables are erroneously connected in the ring configuration of the ring communication system. First, it is assumed that the connection between the port and the cable at the third station 10-3 is mistaken as shown in FIG. 4 during the operation of connecting the communication nodes 10-1 to 10-4 with the cable. That is, the B port 14-2 of the second station 10-2 and the B port 14-3 of the third station 10-3 are connected, and the A port 11-4 of the fourth station 10-4 and the A port of the third station 10-3. It is assumed that 11-3 is connected with a cable.

  After the cable connection is completed, the communication processing units 17-1 to 17-4 of the communication nodes 10-1 to 10-4 are normally connected to the connection port of the own communication node and the connection port of the adjacent communication node. Specifically, it is determined whether A port 11 of the own communication node and port B14 of the adjacent communication node are connected, and B port 14 of the own communication node and A port 11 of the adjacent communication node are connected. Confirmation is performed by negotiation performed in accordance with a predetermined rule. At this time, the communication processing unit 17-2 of the second station 10-2 knows through negotiation that the B port 14-2 of the own station is connected to the B port 14-3 of the third station 10-3. Recognize that the connection port with 10-3 is wrong. Similarly, the communication processing unit 17-4 of the 4th station 10-4 also knows through negotiation that the A port 11-4 of its own station is connected to the A port 11-3 of the 3rd station 10-3. Recognize that the connection port with 10-3 is wrong.

  The communication processing unit 17 of the communication node that has recognized the erroneous connection of the connection port performs a loopback process for the port that is not the erroneously connected port. That is, the communication processing unit 17-2 of the second station 10-2 performs a loopback at the A port 11-2, and the communication processing unit 17-4 of the fourth station 10-4 performs a loopback at the B port 14-4. Do.

  As described above, a ring is formed by disconnecting the three stations 10-3 that cause an erroneous connection. Thereafter, normal communication is performed by this ring.

  According to the first embodiment, even when the communication node 10 or the cable constituting the ring communication system breaks down, the failure point can be separated by performing the loopback, so that the fault-resistant and reliable ring It is possible to realize a state communication system. Further, by connecting the communication nodes 10 in a ring shape, it is not necessary to use a repeater necessary for the connection topology of the star topology or the bus topology, so that all the communication nodes 10 cannot communicate due to the occurrence of a repeater failure. It is possible to eliminate the situation where communication messages concentrate on the repeater. Furthermore, since the number of repeaters can be reduced, there is an effect that the cost for system construction can be reduced. In addition, an erroneous connection at the time of network construction can be found and a portion with an erroneous connection can be disconnected, so that the system construction can be facilitated.

Embodiment 2. FIG.
In the second embodiment, a method for confirming a ring connection state performed after a state in which ports of communication nodes are accurately connected with an Ethernet (registered trademark) cable will be described. For example, as shown in FIG. 1, after the first station 10-1 to the fourth station 10-4 are normally connected, the power of each communication node is turned on in order to configure the ring. At this time, all the communication nodes 10-1 to 10-4 need only be turned on at the same time. For example, there is a case where the third station 10-3 does not start up due to a failure of the power supply system even though the power is turned on. In such a case, loopback must be performed at the A port 11-2 of the second station 10-2 and the B port 14-4 of the fourth station 10-4. In this way, the ring establishment for confirming whether or not a ring-shaped route is configured by the communication nodes 10-1 to 10-4 in the ring communication system immediately after the communication nodes 10-1 to 10-4 are powered on. The confirmation processing procedure will be described below.

  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 10 according to the second embodiment includes a ring establishment confirmation frame issuing unit 21, a frame tour time calculation unit 22, a frame tour time storage unit 23, and a ring establishment determination unit 24. 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 ring establishment confirmation frame issuing unit 21 issues a ring establishment confirmation frame for confirming whether a ring-shaped route (hereinafter simply referred to as a ring) has been established in the ring communication system after power-on at predetermined time intervals. The time at which this ring establishment confirmation frame is issued is embedded in the ring establishment confirmation frame. When the ring establishment confirmation frame issuing unit 21 receives the ring establishment confirmation frame transmitted by itself, the ring establishment confirmation frame issuing unit 21 stops issuing subsequent ring establishment confirmation frames and discards the received ring establishment confirmation frame.

  When the ring establishment confirmation frame issued by the communication node returns from the A port 11, the frame circulation time calculation unit 22 receives the ring establishment confirmation frame and the issue time embedded in the ring establishment confirmation frame. And the frame tour time, which is the time that the ring establishment confirmation frame circulates the ring, is obtained and stored in the frame tour time storage unit 23.

  Since the ring establishment determination unit 24 last received the ring establishment confirmation frame issued by the own communication node or another communication node, the ring establishment confirmation frame has not been detected on the network for a time longer than the frame circulation time. If the state continues for more than the frame cycle time, it is determined that all the communication nodes 10 have recognized the ring connection.

  FIGS. 6-1 to 6-6 are diagrams schematically illustrating an example of the procedure of the ring establishment confirmation process in the ring communication system. First, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-1 of the first station 10-1 transmits a ring establishment confirmation frame in which the issue time is embedded from the B port 14-1 to the normal ring 1 (FIG. 6). -1). Here, the # 1 station 10-1 transmits a first ring establishment confirmation frame 201-1 at time T1, and transmits a second ring establishment confirmation frame 201-2 at time T2 when a predetermined time has elapsed from time T1. Assume that the data is sent to the normal ring 1.

  Thereafter, since the first station 10-1 has not received the ring establishment confirmation frame transmitted by itself, the third station and the fourth ring establishment confirmation frames 201-3 and 201-4 are further normalized at times T3 and T4, respectively. Send to system ring 1. Thereafter, it is assumed that the first ring establishment confirmation frame 201-1 first issued by the first station 10-1 is lost between the fourth station 10-4 and the first station 10-1 for some reason (FIG. 6). -2). The communication nodes 10-2 to 10-3 other than the first station 10-1 pass the ring establishment confirmation frames 201-1 to 201-4 from the first station 10-1 as they are.

  Then, the first station 10-1 receives the second ring establishment confirmation frame 201-2 issued by itself at the A port 11-1, and stores the reception time T6. The frame cyclic time calculation unit 22 of the communication processing unit 17-1 of the first station 10-1 subtracts the issue time T2 embedded in the frame from the reception time T6 of the second ring establishment confirmation frame 201-2. The traveling time T (= T6-T2) is calculated (FIG. 6-3). The calculated frame cycle time is stored in the frame cycle time storage unit 23. Further, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-1 of the first station 10-1 discards the returned second ring establishment confirmation frame 201-2 from the network. Further, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-1 of the first station 10-1 first receives the ring establishment confirmation frame issued by itself, and thereafter stops issuing the ring establishment confirmation frame. (FIG. 6-4). By this time, the # 1 station 10-1 has issued up to the fifth ring establishment confirmation frame 201-5.

  Thereafter, the first station 10-1 sequentially receives and discards the ring establishment confirmation frame issued by itself, and receives and discards the last issued fifth ring establishment confirmation frame 201-5. Thus, the ring establishment confirmation frames 201-1 to 201-5 issued by the first station 10-1 from the network (ring) disappear (FIG. 6-5). The processes from FIG. 6-1 to FIG. 6-5 are performed simultaneously in the other two stations 10-2 to 4-4.

  The ring establishment determination unit 24 of the communication processing unit 17-1 of the first station 10-1 receives all the ring establishment confirmation frames 201-1 to 201-5 issued by the first station 10-1 from the network in FIG. When discarded, measurement of whether or not a ring establishment confirmation frame flows on the network for the frame circulation time obtained in FIG. 6-3 is started. That is, the frame circulation time is set in the timer, and it is determined whether or not a ring establishment confirmation frame transmitted by another communication node 10-2 to 10-4 has been detected before the timeout occurs. During this determination, the timer is reset every time a ring establishment confirmation frame transmitted by another communication node 10-2 to 10-4 is received. This is not only for confirming the establishment of the ring of the own station, but also for obtaining the fact that the other stations have confirmed the establishment of the ring as well. Then, when the ring establishment confirmation frame is not observed on the network (ring) from the time when the ring establishment confirmation frame was last observed by the ring establishment determination unit 24 for the frame circulation time T or longer, Similarly, all the other communication nodes 10-1 to 10-4 determine that the configuration of the network connection (establishment of the ring) has been recognized (FIG. 6-6).

  In the above description, each station has shown the case where the frame establishment time is calculated using the ring establishment confirmation frame returned first among the ring establishment confirmation frames issued by the own station. The cyclic time may be calculated for the ring establishment confirmation frame, and the average value or the maximum value may be set as the frame cyclic time in the timer.

  According to the second embodiment, when communication nodes are connected in a ring shape, the frame establishment time is calculated by using the reception time of the ring establishment confirmation frame and the issuing time thereof, and the ring establishment last flowing on the network When no ring establishment confirmation frame has flowed for more than the frame circulation time from the confirmation frame, it is determined that all communication nodes 10 on the network that circulated the frame were able to recognize the ring connection configuration. Therefore, there is an effect that the frame cycle time can be set according to the number of communication nodes 10 connected in a ring shape. For example, a timer is obtained by setting a frame transit time per communication node in advance and multiplying this by the number of communication nodes 10 constituting the ring communication system and a safety factor for eliminating errors. Compared to the case where the set value is used, the time required for each communication node 10 to determine the recognition of the configuration of the network connection can be shortened.

Embodiment 3 FIG.
In the second embodiment, when a communication node that has issued a ring establishment confirmation frame receives its own ring establishment confirmation frame, it is discarded (terminated). If a failure occurs in one of the communication nodes during the ring establishment confirmation process of the second embodiment and the communication node drops (disconnects) from the network, the communication node is excluded. Loopback is performed to form a new ring. At this time, there is a possibility that the ring establishment confirmation frame issued by the communication node disconnected in the new ring remains. In the third embodiment, a processing method in such a case 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 according to the third embodiment has a configuration further including a received frame information management unit 31 and a received frame information storage unit 32 in FIG. 5 of the second embodiment.

  Each time the reception frame information management unit 31 repeats a ring establishment confirmation frame issued from another communication node 10 received from the A port 11, for the ring establishment confirmation frame, the transmission source communication node and the serial identifying the frame are identified. Received frame information including frame identification information such as a number and frame issuance time (or frame reception time) is acquired and collated with the received frame information stored in the received frame information storage unit 32. If the received ring establishment confirmation frame is not the same as that received in the past (that is, if it is newly issued), the received frame information is received frame information of the transmission source communication node. The storage unit 32 is overwritten and stored. On the other hand, if the received ring establishment confirmation frame has been received in the past, the ring establishment confirmation frame is discarded.

  The reception frame information storage unit 32 stores reception frame information for each communication node 10 connected to the network. For example, as described in the second embodiment, when receiving a ring establishment confirmation frame issued by a certain communication node 10 every predetermined time, the serial numbers are different (the numbers are increased one by one). Therefore, the received frame information of the new ring establishment confirmation frame is overwritten.

  The ring establishment confirmation frame issuing unit 21 has a function of embedding frame identification information such as a serial number for identifying a frame in the ring establishment confirmation frame. When the frame identification information is a serial number, for example, processing such as embedding the serial number incremented by 1 in a ring establishment confirmation frame issued every predetermined time is performed. In addition, the same code | symbol is attached | subjected to the component same as the description mentioned above, and the description is abbreviate | omitted.

  8A to 8D schematically illustrate an example of a processing procedure for discarding a ring establishment confirmation frame issued by a communication node disconnected from the network due to the occurrence of a failure during the ring connection state confirmation process. FIG. The ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-3 of the third station 10-3 receives the first and second serial numbers “No. 1” and “No. 2” at times T1 and T2, respectively. Ring establishment confirmation frames 202-1 and 202-2 are issued, and these frames circulate on the ring (FIG. 8-1).

  9-1 is a diagram illustrating an example of received frame information held by four stations in the state of FIG. 8-1, and FIG. 9-2 is received frame information held by one station in the state of FIG. It is a figure which shows an example. An example of storing the communication node name that is the transmission source of the ring establishment confirmation frame as the received frame information, the serial number embedded in the ring establishment confirmation frame as the frame identification information, and the issue time of the ring establishment confirmation frame is stored. It is shown. It is also possible to use a MAC (Media Access Control) address unique in the world as the node name. As shown in FIG. 9A, the 4th station 10-4 receives the first and second ring establishment confirmation frames 202-1 and 202-2 in order, but the second ring establishment confirmation frame 202 is received. -2 is the newest, the received frame information for the second ring establishment confirmation frame 202-1 is stored. On the other hand, as shown in FIG. 9B, since the first station 10-1 receives only the first ring establishment confirmation frame 202-1, the received frame information is stored. Here, only the 4th station 10-4 and the 1st station 10-1 have been described, but the other stations also acquire and store received frame information regarding the ring establishment confirmation frame transmitted from the B port 14 in the same manner.

  Thereafter, it is assumed that a failure has occurred in the third station 10-3. As a result, the B port 14-2 of the second station 10-2 and the A port 11-4 of the fourth station 10-4 do not receive light from the third station 10-3 when the cable is an optical fiber. When the cable is an electric wire, it is detected that an electrical signal does not come from the third station 10-3, and a failure has occurred in the third station 10-3. As described in the first embodiment, the second station 10-2 performs a loopback at the A port 11-2, and the fourth station 10-4 performs a loopback at the B port 14-4 (FIG. 8-2). ). As a result, the ring establishment confirmation frame issued by the third station 10-3 is left in the new ring established by the loopback. Then, as shown in FIG. 8B, the first ring establishment confirmation frame flows through the standby ring 2.

  Next, the first ring establishment confirmation frame 202-1 is received by the B port 14-4 of the four station 10-4, and since it is in a loopback state, the first ring establishment confirmation frame 202-1 is transmitted from the B port 14. It will be in the state to perform. Prior to this transmission, when the received frame information management unit 31 of the communication processing unit 17-4 of the 4 station 10-4 receives the first ring establishment confirmation frame 202-1, the received frame information is transmitted as described above. The received frame information is collated with the received frame information of the corresponding three stations 10-3 stored in the received frame information storage unit 32. At this time, the serial number of the received first ring establishment confirmation frame 202-1 is “No. 1”. However, as shown in FIG. No. 2 ”, the received frame information management unit 31 recognizes the received first ring establishment confirmation frame 202-1 as a ring establishment confirmation frame repeated in the past, and discards the frame (see FIG. 2). 8-3).

  Similarly, the received frame information management unit 31 of the communication processing unit 17 of the 4 station 10-4 also has the serial number “No. 2” for the received second ring establishment confirmation frame 202-2. As illustrated in FIG. 9A, since the serial number of the received reception frame information is “No. 2”, the reception frame information management unit 31 receives the received second ring establishment confirmation frame 202-2. Recognizes a ring establishment confirmation frame repeated in the past and discards the frame (FIG. 8-4). As described above, when the third station 10-3 is disconnected, the ring establishment confirmation frame issued by the third station 10-3 left in the new ring is removed.

  In FIG. 8C, the first station 10-1 that has received the first and second ring establishment confirmation frames 202-1 and 202-2 flowing through the standby ring 2 does not perform the discarding process first. As described above, only the frame transmitted from the B port 14-1 is filtered, and the data frame flowing from the B port 14-1 to the A port 11-1 is sent without being read in the communication node. It is based on the assumption that it is only.

  This is only an example, and discard processing may be performed on both the data frame transmitted from the A port 11 and the data frame transmitted from the B port 14. In this case, received frame information about the ring establishment confirmation frame transmitted from each port is stored. In the case of a communication node having such a structure, the first station 10-1 can execute the discarding processing of the first and second ring establishment confirmation frames 202-1 and 202-2 in FIG. Become. However, if processing for discarding data frames transmitted from both the A port 11 and the B port 14 is performed, this processing takes time if the transmission speed of the cable is high. There is a possibility that the processing speed becomes slower than the transmission speed, and the communication speed as a whole becomes slow.

  Furthermore, when the frame identification information is a serial number that is incremented by one as in the above-described example, it is possible to determine whether the ring establishment confirmation frame is new or old by using the serial number. Does not require time (issue time, etc.). However, when the frame identification information is formed by other symbols or random values, it is necessary to store the received frame information including time (issue time, etc.). This is because the addition of time information makes it possible to determine whether the received ring establishment confirmation frame is new or old.

  According to the third embodiment, during a ring establishment confirmation process, after any communication node 10 fails and the communication node 10 is disconnected from the network and a new ring is configured, Since the ring establishment confirmation frame issued by the disconnected communication node 10 remaining in the ring is discarded, unnecessary frames of the disconnected communication node 10 can be prevented from staying on the ring. Has an effect.

Embodiment 4 FIG.
In the second embodiment, when a ring establishment confirmation frame is not detected within a time equal to or longer than the frame circulation time after the last detection of the ring establishment confirmation frame, the connection state of the ring is confirmed. It was. By the way, when a failure occurs in one of the communication nodes and the communication node is disconnected from the network during the ring establishment confirmation process of the second embodiment, a loopback is performed so as to exclude the communication node. Is called. In the third embodiment, the method of excluding the ring establishment confirmation frame issued by the excluded communication node from the new ring that has been looped back has been described. However, in the second and third embodiments described above, the ring establishment confirmation process after the loopback is not described. Therefore, in the fourth embodiment, a method for performing the ring establishment confirmation process after the loopback is performed will be described.

  The communication node according to the fourth embodiment has the same configuration as that of the third embodiment shown in FIG. However, the ring establishment confirmation frame issuing unit 21, when issuing the ring establishment confirmation frame, in addition to the issuance time and the identification number for identifying the frame in the ring establishment confirmation frame, It further has a function to embed and transmit path state information indicating whether the port 14 is in a state where transmission / reception is possible (hereinafter referred to as a through state) or a loopback state. In the case of the loopback state, information indicating which of the A port 11 and the B port 14 is performing the loopback is also included. In addition, when the ring establishment confirmation frame issuing unit 21 receives the ring establishment confirmation frame issued by the communication node 10, the ring establishment confirmation frame issuing unit 21 determines that the ring establishment confirmation frame of the ring establishment confirmation frame is the same as the current route state. Issuing is stopped, but if the path status information in the frame is different from the current path status, the ring establishment confirmation frame is continuously issued, and in that case, the frame cycle time by the frame cycle time calculation unit It also has a function that does not perform the calculation process.

  FIGS. 10-1 to 10-5 are diagrams schematically illustrating an example of a procedure for confirming a connection state of a new ring formed after a loopback has occurred. FIGS. 10-1 to 10-5 show a focused state when the four stations 10-4 confirm the establishment of the ring. First, all of the first station 10-1 to the fourth station 10-4 are in a normal state where no failure has occurred, and all the communication nodes 10-1 to 10-4 are in a through state. The ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-4 of the 4th station 10-4 has serial numbers “No. 1” and “No. 2” and route status information respectively at times T1 and T2. It is assumed that first and second ring establishment confirmation frames 203-1 and 203-2 in which information “through” and “through” are embedded are issued (FIG. 10-1).

  Thereafter, it is assumed that a failure has occurred in the third station 10-3. As a result, the B port 14-2 of the second station 10-2 and the A port 11-4 of the fourth station 10-4 detect that a failure has occurred in the third station 10-3, and are described in the first embodiment. As described above, the second station 10-2 performs a loopback at the A port 11-2, and the fourth station 10-4 performs a loopback at the B port 14-4. As a result, the route state of the second station 10-2 becomes “Loop-A” which is looped back at the A port 11-2, and the route state of the fourth station 10-4 is looped back at the B port 14-4. “Loop-B”. At time T3 when a predetermined time has elapsed after the second ring establishment confirmation frame 203-2 is issued, the ring establishment confirmation frame issuing unit 21 of the 4th station 10-4 has the serial number “No. The third ring establishment confirmation frame 203-3 in which the information whose information is “Loop-B” is embedded is issued (FIG. 10-2). When the ring establishment confirmation frame issued by the third station 10-3 is left in the newly configured ring by loopback, it is discarded according to the procedure of the third embodiment described above.

  Thereafter, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-4 of the four station 10-4 receives the first ring establishment confirmation frame 203-1 in which the route state information issued by the own station is “through”. However, the current route state of the local station is “Loop-B”, which is the loopback state of the B port 14, and the two do not match. Subsequently, a ring establishment confirmation frame is issued every predetermined time. (FIG. 10-3). Also, the received first ring establishment confirmation frame 203-1 is discarded. Thereafter, the same applies when the second ring establishment confirmation frame 203-2 is received.

  As time further elapses, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17 of the fourth station 10-4 performs the third ring establishment confirmation frame whose path state information issued by the own station is “Loop-B”. When 203-3 is received, since it coincides with “Loop-B” which is the current route state of the local station, issuance of the ring establishment confirmation frame is stopped (FIG. 10-4). Using this third ring establishment confirmation frame 203-3, the frame cycle time calculation unit 22 calculates the frame cycle time according to the procedure described in the second embodiment. Thereafter, the received third ring establishment confirmation frame 203-3 is discarded.

  Thereafter, the fourth station 10-4 has a fourth ring establishment confirmation frame 203-4 in which the serial number issued by the own station is “No. 4” and the path state information is “Loop-B”, and the serial number is After sequentially receiving the fourth ring establishment confirmation frame 203-5, which is “No. 5” and whose path state information is “Loop-B”, each frame is discarded (FIG. 10-5). Thereafter, as described in FIGS. 6-5 to 6-6 of the second embodiment, by confirming that the time equal to or longer than the frame circulation time has elapsed since the last observation of the ring establishment confirmation frame, The process for confirming the connection state of the ring after the loopback is completed.

  According to the fourth embodiment, even when a communication node 10 that has been disconnected due to a failure occurs during the process of checking the connection state of the ring, a new ring connection is established even if the ring configuration is changed. Corresponding to the state, at least one of the communication nodes 10 participating in the network can receive the ring establishment confirmation frame 203 issued by the own communication node 10 via the final network transmission path. Even if a plurality of communication nodes 10 enter or leave during the ring configuration, the ring configuration is possible.

Embodiment 5 FIG.
FIG. 11A to FIG. 11C are diagrams illustrating a problem that may occur during the ring establishment confirmation process. First, it is assumed that the first station 10-1 to the fourth station 10-4 are connected in a normal state. Then, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-3 of the third station 10-3 includes the serial numbers “No. 1” and “No. 2” embedded at the times T1 and T2, respectively. Assume that the first and second ring establishment confirmation frames 204-1 and 204-2 are issued (FIG. 11-1).

  Thereafter, it is assumed that a failure has occurred in the third station 10-3. As a result, the B port 14-2 of the second station 10-2 and the A port 11-4 of the fourth station 10-4 detect that a failure has occurred in the third station 10-3, and are described in the first embodiment. As described above, the # 2 station 10-2 performs a loopback at the A port 11, and the # 4 station 10-4 performs a loopback at the B port 14-4. As a result, the first and second ring establishment confirmation frames 204-1 and 204-2 issued by the third station 10-3 are left in a new ring configured by loopback (FIG. 11). -2).

  Further, before the first and second ring establishment confirmation frames 204-1 and 204-2 issued by the third station 10-3 are discarded, the fifth station 10- Suppose 5 has entered the network. In this case, a new ring configuration is performed again, and the second station 10-2 shifts from the loopback state at the A port 11-2 to the through mode, and the fourth station 10-4 loops back at the B port 14-4. The state is changed to the through mode (FIG. 11-3). As a result, the first and second ring establishment confirmation frames 204-1 and 204-2 issued by the third station 10-3 circulate in the standby ring 2. These first and second ring establishment confirmation frames 204-1 and 204-2 flow in the standby ring 2 that is not normally used, and further flow from the B port 14 to the A port 11 in each communication node 10. Because the filter is not applied, it will continue to flow forever without being discarded.

  Therefore, in the fifth embodiment, a ring establishment confirmation processing method for solving such a problem will be described. FIG. 12 is a block diagram schematically showing a functional configuration of the communication node according to the fifth embodiment. The communication processing unit 17 of the communication node of the fifth embodiment has a configuration further including a loopback state control unit 51 in FIG. 7 of the third embodiment. 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 loopback state control unit 51 stores route state transition information indicating the transition of the route state of the self-communication node, and adjacent communication nodes are disconnected to form a new ring. If another communication node joins in place of the disconnected communication node before the processing is completed, the ring establishment confirmation frame issued by the disconnected communication node is discarded, and finally all ring establishment confirmation frames Has a function of controlling the port so as not to release the loopback state until it is not detected for a time longer than the frame circulation time (that is, until the ring establishment confirmation process is completed).

  Next, the operation will be described with reference to FIG. 11-1 and FIGS. 13-1 to 13-2. FIG. 13A to FIG. 13B are diagrams schematically illustrating an example of a procedure of the ring establishment confirmation process when a new communication node enters in place of the disconnected communication node. First, as shown in FIG. 11A, the first station 10-1 to the fourth station 10-4 are connected in a normal state, and the ring establishment of the communication processing unit 17-3 of the third station 10-3 is established. The confirmation frame issuing unit 21 issues first and second ring establishment confirmation frames in which serial numbers of “No. 1” and “No. 2” are embedded at times T1 and T2, respectively.

  Thereafter, it is assumed that a failure has occurred in the third station 10-3. As a result, the B port 14-2 of the second station 10-2 and the A port 11-4 of the fourth station 10-4 detect that a failure has occurred in the third station 10-3, and are described in the first embodiment. As described above, the second station 10-2 performs a loopback at the A port 11-2, and the fourth station 10-4 performs a loopback at the B port 14-4. At this time, the loopback state control unit 51 of the communication processing units 17-2 and 17-4 of the second station 10-2 and the fourth station 10-4 indicates that the path state has transitioned from the through state to the loopback state. The route state transition information is stored (FIG. 13-1).

  Further, before the first and second ring establishment confirmation frames 205-1 and 205-2 issued by the third station 10-3 are discarded, the fifth station 10-5 is replaced with the third station 10-3 which has been disconnected. Suppose that has entered the network. At this time, the 3rd station 10-3 detects that the 5th station 10-5 has entered the network, but the 5th station 10-5 is in a state where it has transitioned from the through state to the loopback state in the path state transition information. The ring configuration with 10-5 is not performed (FIG. 13-2). That is, in order to prevent the circulation of the ring establishment confirmation frame issued by the third station 10-3 in the standby ring 2 described in FIG. 11-3, the loopback state control of the communication processing unit 17-2 of the second station 10-2 The unit 51 maintains the state of being looped back at the A port 11-2 and keeps the B port 14-2 in an unusable state, so that the communication processing unit 17-4 of the 4 station 10-4 The loopback state control unit 51 controls the port A11-4 to be in an unusable state while maintaining the loopback state in the B port 14-4. This state is maintained until the new ring establishment confirmation process by loopback in FIG.

  Thereafter, as described in the second embodiment, after the ring establishment confirmation frames 205-1 and 205-2 are all discarded on the ring, the communication between the second station 10-2 and the fourth station 10-4 is performed. The loopback state control unit 51 of the processing unit 17 controls the route state from the loopback state to the through state, and rewrites the route state transition information to the through state. Thereby, the ring establishment confirmation frame issuing unit 21 of the second station 10-2 and the fourth station 10-4 executes a new ring establishment confirmation process in the network including the newly entered five stations 10-5. The second station 10-2 and the fourth station 10-4 are communication nodes that can know the end of the ring establishment confirmation process of the ring when the third station 10-3 is disconnected, and the fifth station 10-5. Therefore, a new ring establishment confirmation process is performed from these 2 stations 10-2 and 4 stations 10-4.

  According to the fifth embodiment, before the adjacent communication node is disconnected and the ring establishment confirmation frame issued by the communication node 10 is present in the standby system and discarded, it is replaced with the disconnected communication node. When another communication node enters the network, it prevents the ring establishment confirmation frame issued by the communication node disconnected from the ring configured by the entry of another new communication node from continuing to flow without being discarded. It has the effect of being able to.

Embodiment 6 FIG.
In this sixth embodiment, a configuration of a communication node that prevents a ring establishment confirmation frame from staying in the standby ring as in the fifth embodiment, and a processing method thereof will be described. The configuration of the communication node used in the sixth embodiment is the same as that shown in FIG. 7 of the third embodiment. However, the received frame information management unit 31 of the communication node according to the sixth embodiment circulates the standby ring 2, and among the frames passing from the B port 14 to the A port 11, the ring establishment issued by the own communication node is established. For the confirmation frame only, the received frame information including the frame identification information is obtained and compared with the received frame information stored in the received frame information storage unit 32. The received frame information for the establishment confirmation frame is stored in the reception frame information storage unit 32, and if the received frame information is the same as that received in the past, the ring establishment confirmation frame is discarded. In addition, the received frame information storage unit 32 also stores received frame information of a ring establishment confirmation frame issued by the own communication node among frames that circulate in the standby ring 2 and acquired by the received frame information management unit 31. In addition, the same code | symbol is attached | subjected to the component same as the description mentioned above, and the description is abbreviate | omitted.

  Next, the operation will be described with reference to FIGS. 14-1 to 14-6. FIGS. 14-1 to 14-6 are schematic diagrams illustrating an example of a procedure for discarding a ring establishment confirmation frame that flows through the standby ring. First, the normal system ring 1 between the first station 10-1 and the second station 10-2 is disconnected from the state in which the first station 10-1 to the fourth station 10-4 are normally connected. Assuming that the power supply of 1 is turned off and turned off, the A port 11-2 of the second station 10-2 detects that the normal ring 1 is disconnected, and as described in the first embodiment, the B port 14 -2 performs loopback. Further, the B port 14-4 of the 4 station 10-4 detects that the communication with the 1 station 10-1 cannot be performed, and the loopback is performed at the A port 11-4 as described in the first embodiment. Perform (FIG. 14-1).

  Then, assuming that the power of station 1 10-1 is turned on and turned on, B port 14-4 of station 4-10-4 detects the return of station 1-10-1 and resumes normal through from the loopback state. Transition to the state. Further, the B port 14-1 of the first station 10-1 that is turned on detects that the normal ring 1 between the first station 10-1 and the second station 10-2 is disconnected, and As described in the first embodiment, loopback is performed at the A port 11-1. Then, the ring establishment confirmation frame issuing unit 21 of the reception processing unit 17-1 of the A station 10-1 transmits the ring establishment confirmation frame 220 having the serial number “No. 1” from the A port 11-1 to the standby ring 2 (Figure 14-2).

  After that, when the disconnection of the normal ring 1 between the first station 10-1 and the second station 10-2 is repaired, the B port 14-1 of the first station and the A port 11-2 of the second station The normal ring 1 is restored and the loopback state is changed to the normal through state (FIG. 14-3). Thereby, the 1st station 10-1 to the 4th station 10-4 are connected by the normal system ring 1 and can perform communication without a loopback. For this reason, the ring establishment confirmation frame 220 issued by one station is left behind in the standby ring 2.

  Thereafter, it is assumed that the ring establishment confirmation frame 220 flows in the standby ring 2 and passes between the second station 10-2 and the first station 10-1 (FIG. 14-4). At this time, the received frame information management units 31 of the communication processing units 17-2 to 17-4 of the second station 10-2 to the fourth station 10-4 that receive the frames flowing through the standby ring 2 are respectively connected to the B port 14-2. 1 receives the ring establishment confirmation frame 220 issued by one station, but since it is not issued by the own communication node, it directly flows from the A port 11-2 to 11-4 to the standby ring 2, and the ring establishment confirmation frame 220 220 is transferred.

  When the first station 10-1 receives the ring establishment confirmation frame 220 issued by itself from the B port 14-1, the received frame information management unit 31 of the communication processing unit 17-1 stores the received frame information storage unit 32 in the received frame information storage unit 32. With reference to the received frame information, it is determined whether or not it is a ring establishment confirmation frame 220 received in the past. In this case, since it has not been received in the past, the serial number “No. 1” of the ring establishment confirmation frame 220 is acquired and stored in the reception frame information storage unit 32 as reception frame information. 1 is sent out (FIG. 14-5).

  Thereafter, the ring establishment confirmation frame 220 circulates in the standby ring 2. However, since the second station 10-2 to the fourth station 10-4 are not the ring establishment confirmation frame 220 issued by the own station, they are transferred as they are. When the ring establishment confirmation frame 220 is received at the B port 14-1 of the first station 10-1, the reception frame information management unit 31 of the communication processing unit 17-1 refers to the reception frame information storage unit 32, Since there is received frame information corresponding to the serial number “No. 1”, it is determined that it has been received in the past, and the ring establishment confirmation frame 220 is discarded (FIG. 14-6). In the above description, the description has focused on the process of discarding the ring establishment confirmation frame 220 flowing in the standby ring 2 after becoming normal, but the normal state returned to normal shown in FIG. In the system ring 1, the ring establishment confirmation process described in the above-described embodiment is performed in parallel.

  According to the sixth embodiment, the received frame information is acquired for the ring establishment confirmation frame 220 issued by the own communication node flowing through the standby ring 2, and the ring establishment confirmation frame received for the second time based on the received frame information. Since the reception frame information management unit 31 of the communication processing unit 17 has a function of discarding 220, the ring establishment confirmation frame 220 that has remained in the standby ring 2 for some reason is stored in the standby ring 2 It has the effect of being able to be disposed of without being retained. Further, only the ring establishment confirmation frame 220 issued by the own communication node is received and the transferred record is kept, and only the ring establishment confirmation frame 220 issued by another node is forwarded. There is also an effect that it is possible to suppress the load applied to the frame processing.

Embodiment 7 FIG.
In the seventh embodiment, the ring establishment confirmation process is completed, and a failure occurs in a communication node constituting the network in a state where a normal communication message in which the token frame is flowed to the normal ring 1 can be transmitted. A ring establishment confirmation process when the communication node is disconnected from the network will be described.

  FIG. 15 is a block diagram schematically showing a functional configuration of the communication node according to the seventh embodiment. The communication processing unit 17 of the communication node according to the seventh embodiment has a configuration further including a frame discard processing unit 61 in FIG. 12 of the fifth embodiment. 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 frame discard processing unit 61 performs processing for discarding frames other than the ring establishment confirmation frame when in the ring establishment confirmation processing state. For example, when a failure occurs in one of the communication nodes that make up the network from the normal transmission state in which a token frame is sent during the ring, the state moves to the state of confirmation processing for ring establishment. At that time, a frame unrelated to the ring establishment confirmation process such as a token frame or a data frame flowing in the newly reconfigured ring is discarded.

  FIGS. 16-1 to 16-5 are diagrams schematically illustrating an example of a procedure for deleting a frame that is not related to the ring establishment confirmation process in the case of shifting from the normal communication state to the ring establishment confirmation process. . First, it is assumed that the network is in a normal communication state. Here, it is assumed that the third station 10-3 receives the token frame 208 from the second station 10-2 and acquires the transmission right. Thereafter, the third station 10-3 sends a token reception completion notification frame 206 indicating that the own station (third station 10-3) has acquired the token frame 208 to the second station 10-2 that is the transmission source of the token frame 208. And the data frame 207 is transmitted to the other communication node to which the data is to be sent, and then the token frame 208 is released (FIG. 16-1).

  Thereafter, it is assumed that a failure has occurred in the third station 10-3 (FIG. 16-2). As a result, the B port 14-2 of the second station 10-2 and the A port 11-4 of the fourth station 10-4 detect that a failure has occurred in the third station 10-3, and are described in the first embodiment. As described above, the second station 10-2 performs a loopback at the A port 11-2, and the fourth station 10-4 performs a loopback at the B port 14-4. As a result, the token reception completion notification frame 206 and the data frame 207 issued by the third station 10-3 are left in a new ring configured by loopback. The second station 10-2 and the fourth station 10-4 that have detected that a failure has occurred in the third station 10-3 transition from the normal communication state to the ring establishment confirmation processing state. Therefore, the ring establishment confirmation frame issuing units 21 of the communication processing units 17-2 and 17-4 of the second station 10-2 and the fourth station 10-4 respectively start issuing ring establishment confirmation frames (FIG. 16-3). . At this time, the # 1 station 10-1 is still in a normal communication state. For this reason, when the token reception completion notification frame 206 is received from the A port 11-1, since it is not addressed to the own station, it is sent to the B port 14-1 as it is.

  In addition, since the second station 10-2 is in a state of issuing a ring establishment confirmation frame every predetermined time, the second station 10-2 is in a reception waiting state waiting for the ring establishment confirmation frame transmitted by itself to return. . At this time, the frame discard processing unit 61 of the communication processing unit 17-2 discards the frame received from the A port 11-2 when it detects a frame unrelated to the state of the ring establishment confirmation processing (FIG. 16-). 4). Here, the received token reception completion notification frame 206 is discarded.

  At this time, the first station 10-1 receives the first ring establishment confirmation frame 210-1 from the A port 11-1 from the fourth station 10-4, and performs processing to send it to the B port 14-1. Yes. As a result, the ring establishment confirmation frame issuing unit 21 of the communication processing unit 17-1 of the first station 10-1 knows that it has transitioned to the ring establishment confirmation state, and starts issuing its own ring establishment confirmation frame. Become. The data frame 207 issued by the third station 10-3 is received earlier than the ring establishment confirmation frame 210-1 from the fourth station 10-4, and the ring establishment confirmation state is entered when the data frame 207 is received. At this time, the first station 10-1 does not discard the data frame.

  Thereafter, the frame discard processing unit 61 of the communication processing unit 17-2 of the second station 10-2 performs processing to discard the data frame 207 issued by the third station 10-3 received from the A port 11-2 (FIG. 16). -5). As described above, after the transition from the normal communication state to the ring establishment confirmation processing state, the processing for discarding the frame issued in the normal communication state left in the new ring ends. Thereafter, the ring establishment confirmation process is performed according to the procedure described in the second to fifth embodiments.

  According to the seventh embodiment, when a transition from the normal communication state to the ring establishment confirmation processing state is made, it is possible to avoid a situation where a frame issued in the communication state stays in a new ring. It has the effect of being able to.

Embodiment 8 FIG.
In this Embodiment 8, after the ring establishment in Embodiments 2 to 6 described above, the station information notification process for distributing the station information related to each communication node to all the communication nodes on the network will be described.

  FIG. 17 is a diagram schematically showing a functional configuration of a communication node according to the eighth embodiment. The communication processing unit 17 of this communication node includes a ring establishment confirmation processing unit 20, a station information management unit 71, a frame tour time calculation unit 72, a frame tour time storage unit 73, a station information notification completion determination unit 74, and a network configuration information storage unit. 75. The ring establishment confirmation processing unit 20 is a collection of the respective processing units in the communication processing unit 17 that execute the ring establishment confirmation processing described in the second to sixth embodiments. In addition, the same code | symbol is attached | subjected to the component same as the figure used in embodiment mentioned above, and the description is abbreviate | omitted.

  The station information management unit 71 is necessary for creating the configuration information of the network for all communication nodes in the network in which the ring is established after the ring establishment in the second to sixth embodiments described above. A station information notification frame including station information of a self-communication node is issued every predetermined time. The time at which this station information notification frame is issued is embedded in this station information notification frame. Further, the station information management unit 71 stops issuing the station information notification frame after the time when the station information notification frame transmitted by itself is first received, and discards the received station information notification frame. Here, the station information is the MAC address of the own communication node, the own communication node identification information such as the station number for identifying the own communication node, and which port is in the loop back state when the own communication node is in the loop back state. Loopback state information indicating the MAC address of the communication node located upstream and downstream. Further, when receiving the station information notification frame transmitted from another communication node, the station information management unit 71 stores the station information in the network configuration information storage unit 75.

  When the station information notification frame issued by the communication node returns from the A port 11, the frame cycle time calculation unit 72 receives the station information notification frame and the issue time embedded in the station information notification frame. And the frame cycle time, which is the time that the station information notification frame circulated around the ring, is obtained. The frame tour time storage unit 73 stores the frame tour time calculated by the frame tour time calculation unit 72.

  The station information notification completion determination unit 74 stops the issuance of the station information notification frame and then receives the station information notification frame last issued by the own communication node or another communication node. It is determined whether or not the station information notification frame has not been detected on the network. If this state continues for more than the frame cycle time, it is determined that all communication nodes on the network have acquired station information from each other. To do.

  The network configuration information storage unit 75 stores network configuration information that is station information associated with communication nodes that configure a network in which a ring is established. That is, the network configuration information is information managed by associating station information received from another communication node with the communication node. From this network configuration information, each communication node can know the connection state of the network in which the ring is established.

  FIGS. 18-1 to 18-6 are diagrams schematically illustrating an example of a procedure of station information notification processing in the ring communication system. First, the station information management unit 71 of the communication processing unit 17-1 of the first station 10-1 sends a station information notification frame in which the issue time is embedded from the B port 14-1 to the normal ring 1 (FIG. 18-1). ). Here, the first station 10-1 transmits the first station information notification frame 211-1 at the time T1, and the second station information notification frame 211-2 at the time T2 when a predetermined time has elapsed from the time T1. Assume that the data is sent to the normal ring 1.

  After that, since the first station 10-1 has not received the station information notification frame transmitted by itself, the third and fourth station information notification frames 211-3 and 211-4 are further normalized at times T3 and T4, respectively. Send to system ring 1. Thereafter, it is assumed that the first station information notification frame 211-1 first issued by the first station 10-1 is lost between the fourth station 10-4 and the first station 10-1 for some reason (FIG. 18). -2). When the communication nodes 10-2 to 10-4 other than the first station 10-1 receive the station information notification frame from the first station 10-1, the station information management of the communication processing units 17-2 to 17-4 is performed. The unit 71 copies the station information and stores it in the network configuration information storage units 75-1 to 75-4 in association with the first station 10-1.

  Next, the first station 10-1 receives the second station information notification frame 211-2 issued by itself at the A port 11-1. For the first station 10-1, since the first station information notification frame 211-1 has disappeared on the network, the second station information notification frame 211-2 first received by the station information notification frame 211-2. Therefore, the reception time T6 is stored. The frame cycle time calculation unit 72 of the communication processing unit 17-1 of the first station 10-1 subtracts the issue time T2 embedded in the frame from the reception time T6 of the second station information notification frame 211-2. The traveling time T (= T6-T2) is calculated (FIG. 18-3). The calculated frame cycle time is stored in the frame cycle time storage unit 73. Further, the station information management unit 71 of the communication processing unit 17-1 of the first station 10-1 discards the returned second station information notification frame 211-2 from the network. Further, since the station information management unit 71 of the communication processing unit 17-1 of the first station 10-1 first receives the station information notification frame issued by itself, it stops issuing the station information notification frame thereafter ( FIG. 18-4). By this time, the first station 10-1 has issued up to the fifth station information notification frame 211-5.

  Thereafter, the first station 10-1 sequentially receives and discards the ring establishment confirmation frame issued by itself, and receives and discards the last-issued fifth station information notification frame 211-5. Thus, there is no ring establishment confirmation frame issued by the first station 10-1 from the network (FIG. 18-5). The processes from FIG. 18-1 to FIG. 18-5 are also performed at the same time in the other two stations 10-2 to 4-4 constituting the network.

  The station information notification completion determination unit 74 of the communication processing unit 17-1 of the first station 10-1 performs all the station information notification frames 211-1 to 211- issued by the first station 10-1 from the network in FIG. 18-5. When 5 is discarded, measurement of whether or not the station information notification frame does not flow on the network is started for the frame circulation time obtained in FIG. 18-3. That is, the frame circulation time is set in the timer, and it is determined whether or not the station information notification frame transmitted from the other communication nodes 10-2 to 10-4 is detected before the timeout occurs. During this determination, each time the station information notification frame transmitted from the other communication nodes 10-2 to 10-4 is received from the A port 11-1, the timer is reset. This not only confirms that the station information of the own station has been distributed to all the communication nodes 10-1 to 10-4, but also the station information of other stations similarly to all the communication nodes 10-1 to 10-4. This is to confirm that it has been distributed. Then, the station information notification completion determination unit 74 determines that if the station information notification frame is not observed in the network for a frame circulation time T or longer after the issuance of the station information notification frame is stopped, that is, the timer times out. In this case, it is determined that all the other communication nodes on the network have been able to distribute the station information to all the communication nodes as well (FIG. 18-6).

  According to the eighth embodiment, since the station information notification frame including the station information of the own communication node is circulated after the ring is established, the station information notification frame is returned to the own station again. Thus, it can be confirmed that the other station has received the station information notification frame. As a result, as in the case of building with the conventional Ethernet (registered trademark) or the like, the necessary frame is not required since the reception response message from each communication node is not required after the station information is notified to each communication node. It is possible to reduce the number and to easily confirm that the station information of all the communication nodes is shared.

  In addition, since the communication node continuously issues the station information notification frame and stops issuing the station information notification frame when the station information notification frame issued by itself is first returned, In addition to preventing delays in notification of station information due to loss on the route, it is possible to shorten the response time when the station information notification frame is lost.

  Furthermore, the frame cycle time for which the station information notification frame circulates is measured, and this frame cycle time is used to determine whether all communication nodes on the network have distributed the station information to each other. In accordance with the number of communication nodes), it is possible to set a time (time-out value) for determining whether all communication nodes have distributed station information to each other. As a result, the time-out value differs between a ring configuration with a small number of communication nodes and a ring configuration with a large number of communication nodes. Therefore, when the number of communication nodes is small, the setting of station information exchange is completed more quickly. .

  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.

DESCRIPTION OF SYMBOLS 1 Regular system ring 2 Standby system ring 10, 10-1 to 10-5 Communication node 11, 11-1 to 11-5 A port 14, 14-1 to 14-5 B port 17, 17-1 to 17-5 Communication processing unit 20 Ring establishment confirmation processing unit 21 Ring establishment confirmation frame issuing unit 22, 72 Frame tour time calculation unit 23, 73 Frame tour time storage unit 24 Ring establishment determination unit 31 Received frame information management unit 32 Received frame information storage unit 51 Loopback state control unit 61 Frame discard processing unit 71 Station information management unit 74 Station information notification completion determination unit 75 Network configuration information storage unit

Claims (17)

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,
First and second ports having an input section for inputting a frame and an output section for outputting the frame;
When the first and second ports are normal, the reception process of the frame input from the input unit of the first port is performed, the frame is transmitted from the output unit of the second port, and the adjacent communication node When a communication error occurs between the port and the adjacent communication node, the reception process of the frame input from the input unit of the port on the side different from the port connected to the adjacent communication node is performed, and the input unit to which the frame is input is the same When the loopback process for transmitting the frame is performed from the output unit of the other port and the other communication node performs the loopback process, the reception process of the frame input from the input unit of the second port is not performed. Communication processing means for transmitting the frame from the output unit of the first port;
With
The communication processing means includes
When power is turned on or when a self-communication node performs a loopback process to form a new ring, it issues a ring establishment confirmation frame in which the issue time is embedded, and receives the ring establishment confirmation frame that circulates the ring , Ring establishment confirmation frame issuing means for stopping issuing subsequent ring establishment confirmation frames;
Frame cycle time calculation for calculating a frame cycle time obtained by subtracting the issue time in the ring establishment confirmation frame from the time when the ring establishment confirmation frame issued by the ring establishment confirmation frame issuing unit and circulated around the ring is received. Means,
Ring establishment determination means for determining whether or not to detect a ring establishment confirmation frame flowing in the ring for a time equal to or longer than the frame circulation time after the issuance of the ring establishment confirmation frame is stopped;
A communication node comprising: The ring establishment confirmation frame issuing means of the communication processing means has a function of embedding unique information for uniquely identifying the frame in the ring establishment confirmation frame;
The communication processing means includes
Received frame information storage means for storing received frame information including a source communication node of a ring establishment confirmation frame received from another communication node in the communication system and the specific information;
The received frame establishment confirmation frame received by comparing the received frame information acquired from the ring establishment confirmation frame from the other communication node with the received frame information corresponding to the other communication node in the received frame information storage means. Is a frame received in the past, received frame information management means for discarding the frame,
The communication node according to claim 1, further comprising: The communication processing means includes
After the first adjacent communication node adjacent to the communication node is disconnected from the ring by the ring establishment confirmation frame issuing means and a new ring is formed by performing loopback processing, the ring establishment in this ring is established. When the second adjacent communication node has entered the position of the first adjacent communication node before the confirmation process is completed, the communication node adjacent to the second adjacent communication node is looped back. The communication node according to claim 1, further comprising a loopback state control means for controlling the state until the ring establishment confirmation process in the ring is completed. When the normal communication node or another communication node makes a normal transition from the state in which the loopback process is being performed, the received frame information management means includes the ring establishment confirmation frame input from the input unit of the second port. Obtain the received frame information including the unique information of the ring establishment confirmation frame issued by the own communication node,
When the received frame information storage means does not have the same received frame information, the acquired received frame information is stored in the received frame information storage means,
The communication node according to claim 2, further comprising a function of discarding the ring establishment confirmation frame when there is the same received frame information. The communication processing means includes
A frame that discards frames other than the ring establishment confirmation frame among the received frames when the token frame is passed through the ring and communication is performed using the token passing method to change to the ring establishment confirmation processing state. The communication node according to claim 1, further comprising a discard processing unit.   The ring establishment confirmation frame issuing means of the communication processing means, when detecting reception of a ring establishment confirmation frame, makes a transition to a ring establishment confirmation processing state and starts issuing a ring establishment confirmation frame. The communication node according to claim 1. The communication processing means includes
When the ring establishment confirmation process is completed, a station that issues a station information notification frame including station information related to its own communication node necessary for creating network configuration information and receives the station information notification frame that has circulated around the ring The communication node according to claim 1, further comprising information management means.   8. The communication according to claim 7, wherein the station information management unit of the communication processing unit issues a station information notification frame until the issued station information notification frame circulates around the ring and returns. node. When the station information management unit of the communication processing unit embeds the issuance time of the frame in the station information notification frame and receives the station information notification frame that has circulated in the ring shape, the station information notification frame is issued thereafter. Further has the function of stopping
The communication processing means includes
Frame cycle time calculation means for calculating a frame cycle time obtained by subtracting the issue time in the station information notification frame from the time at which the station information notification frame issued by the station information management unit and circulated around the ring is received. ,
Station information notification completion determination means for determining whether or not to detect a station information notification frame flowing in the ring for a time equal to or longer than the frame cycle time after the issuance of the station information notification frame;
The communication node according to claim 8, further comprising: A ring establishment confirmation method for a communication system in which a plurality of communication nodes connected by Ethernet (registered trademark) are connected in a ring shape,
The communication node issues a ring establishment confirmation frame with the issue time of the frame embedded and receives the ring establishment confirmation frame when the power is turned on or when the own communication node performs a loopback process to form a new ring. Then, a ring establishment confirmation frame issuance process for stopping issuing subsequent ring establishment confirmation frames,
A ring establishment confirmation step in which the communication node receives the ring establishment confirmation frame issued in the ring establishment confirmation frame issue step to confirm that the ring has been established;
Including
The ring establishment confirmation step includes
A frame cycle time calculating step for calculating a frame cycle time by subtracting the issue time in the ring establishment confirmation frame from the time at which the ring establishment confirmation frame is received;
A ring establishment determination step of confirming that the ring has been established when the ring establishment confirmation frame has not flowed on the ring for more than the frame cycle time after stopping issuing the ring establishment confirmation frame;
A ring establishment confirmation method for a communication system, comprising: In the ring establishment confirmation frame issuance step, unique information for uniquely identifying the frame is embedded in the ring establishment confirmation frame,
A received frame information storage step of storing received frame information including a source communication node of a ring establishment confirmation frame received from another communication node in the communication system and the unique information;
The received frame information obtained from the ring establishment confirmation frame received from the other communication node is compared with the received frame information corresponding to the other communication node already stored, and the received frame has been received in the past. If it is a frame, a received frame information management step for discarding the frame;
The ring establishment confirmation method for a communication system according to claim 10, comprising: After the first communication node disconnects from the ring and performs a loopback process to form a new ring, before the ring establishment confirmation process for the new ring is completed, the first communication node When a second communication node enters the node position,
The communication node adjacent to the second communication node further includes a loopback control step of maintaining the state of the loopback processing until the ring establishment confirmation processing in the new ring is completed. Item 11. A method for confirming ring establishment of a communication system according to Item 10. In the received frame information management step, when the own communication node or other communication node has successfully transitioned from the state in which the loopback process is being performed, the received frame information management step includes the ring establishment confirmation frame input from the input unit of the second port , Receive the received frame information including the unique information of the ring establishment confirmation frame issued by the own communication node,
If there is no received frame information stored for the acquired frame, store the received frame information acquired,
12. The ring establishment confirmation method for a communication system according to claim 11, further comprising a process of discarding the ring establishment confirmation frame when there is received frame information for the acquired frame. When the token frame is passed through the ring and communication is performed using the token passing method, the process proceeds to the ring establishment confirmation step for confirming ring establishment.
The ring establishment confirmation method for a communication system according to claim 10, further comprising a frame discard processing step of discarding frames other than the ring establishment confirmation frame among the received frames.   11. The station information management step of transmitting a station information notification frame including station information related to a local communication node necessary for creating network configuration information after the ring establishment confirmation step. Method for confirming ring establishment in the communication system of   The ring establishment confirmation of the communication system according to claim 15, wherein the station information management step issues a station information notification frame until the issued station information notification frame circulates around the ring and returns. Method. In the station information management step, the issuance time of the frame is embedded in the station information notification frame, and when the issued station information notification frame is received, issuance of subsequent station information notification frames is stopped,
A frame cycle time calculating step for calculating a frame cycle time obtained by subtracting the issue time in the station information notification frame from the time at which the station information notification frame issued in the station information management step that has circulated the ring is received; ,
After the issuance of the station information notification frame is stopped, it is determined that the station information has been exchanged between communication nodes on the network when the station information notification frame does not flow on the ring for more than the frame cycle time. A station information notification completion determination step,
The ring establishment confirmation method for a communication system according to claim 16, further comprising:

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