WO2008068813A1 - Ring type network - Google Patents

Abstract

Intended is to provide a ring type network using a plurality of rings, which can control, even if the rings to be connected are constituted without fixing the positions of a switch for closing a port, the individual rings at a normal time by the same control method without forming a loop path, and which can prevent the loop path from occurring even at a trouble time thereby to switch the path. A switching priority to two rings is set at two switches belonging to the two rings. When a master switch to be set at an arbitrary position in each ring operates normally, one port is closed, and a control frame for conduction confirmation is periodically sent from the two ports thereby to monitor the soundness of its own ring. In this procedure, in case a trouble occurs in a link belonging to two adjoining rings, the two belonging switches send a switching requesting instruction and a switching unrequesting instruction according to the switching priority, to a corresponding master switch, and the switching is executed at only such one of the two adjoining rings having the link trouble as has been requested for the switching.

Description

 Specification

 Ring network technology

 The present invention relates to a ring network using Ethernet (registered trademark) technology, and more particularly to a ring network in which a plurality of ring transmission lines (rings) are connected.

 Background art

 [0002] Currently, Ethernet (registered trademark) technology is widely used in the field of local area networks (LANs) because devices are inexpensive and easy to manage. In recent years, a wide area network (WAN) using Ethernet technology has been built with the large capacity of Ethernet (registered trademark) switches (switching knobs and bridges: hereinafter referred to simply as “switches”). It has come to be. Along with this, high reliability is also required for networks constructed with Ethernet (registered trademark) technology. In other words, even if a failure occurs, it is necessary to quickly avoid the failure and continue communication. For this reason, there is a demand for technology that can avoid obstacles at high speed by minimizing the range of influence on the network.

[0003] By the way, in a ring network using Ethernet (registered trademark) technology, if a loop route occurs, a broadcast frame continues to flow, and the network is congested, so that the network cannot be operated normally. The phenomenon occurs. As a method of avoiding this, using a protocol called STP (Spanning Tree Protocol) defined in Non-Patent Document 1, a specific port of the switch is blocked so that a loop path does not occur. A method is known in which continuity is confirmed by periodically exchanging control frames. Here, “blocking” means that a data frame is not allowed to pass but a control frame is allowed to pass. However, the method using STP has a problem in that it takes several tens of seconds to reconfigure a new route when a route failure occurs, so high-speed switching cannot be performed. Note that STP is not a protocol limited to ring networks. [0004] Therefore, conventionally, a method has been proposed in which the occurrence of a loop route is prevented without using STP, and a high-speed switch is made to a new route even when a failure occurs (for example, Patent Document 1). A method has been proposed in which, after a failure is recovered, a transition to the original normal path at high speed is made (for example, Patent Document 2). Here, the disclosed contents of Patent Document 1 will be schematically described with reference to FIGS. FIG. 20 is a diagram for explaining a normal control method in a conventional ring network composed of one ring. FIG. 21 is a diagram for explaining a failure switching method in the ring type network shown in FIG. FIG. 22 is a diagram for explaining a control method in a conventional ring network composed of a plurality of rings.

 In FIG. 20, one switch 141 among the switches 141 to 146 constituting the ring network is defined as a control switch that is located at the connection end of the ring and closes one port when it is normal. That is, of the two ports of the control switch 141, the one-side port 148 on the counterclockwise transmission line side (switch 142 side in FIG. 20) is set as a port without performing the closing operation, and the clockwise transmission line side (see FIG. In 20, switch 146 side) reverse side port 149 is set as the port that performs blocking operation. The control switch 141 periodically transmits the control frame 147 for the one-side port 148 force, and receives the control frame 147 via the switch 142 to the switch 1 46 at the reverse-side port 149, thereby monitoring the normality of the ring. On the reverse side port 149, while the control frame 147 can be received, a blocking operation is performed to prevent the occurrence of a loop path.

 [0006] As shown in FIG. 21, when a failure occurs in the link between the switch 143 and the switch 144, the reverse port 149 of the control switch 141 cannot receive the control frame 147. The switch 141 recognizes that the ring has failed, and releases the closed port 149 from being closed. As a result, a new route can be secured. In the example shown in FIG. 21, communication between the switch 143 and the switch 144 is made possible by a new route via the switch 142 to the switch 141 to the switch 146 to the switch 145. In this case, the loop path does not occur because there is a fault location on the ring. In addition, by shortening the transmission period of the control frame 147, it is possible to switch the path faster than STP.

[0007] While the above is a control method in the case of one ring, Patent Document 1 also discloses a control method in a case where a plurality of rings are connected. In Figure 22, with two rings A configuration example of a conventional ring network configured is shown. In FIG. 22, switches 204 and 208 of switch 201 to switch 210 arranged on the ring each have three ports, and one of them is directly connected to each other. Yes. Accordingly, the switch 201 to the switch 202 to the switch 203 to the switch 204 to the switch 2 08 to the switch 209 to the switch 210 to the switch 201 to the upper ring along the route of the switch 201 to the switch 204 to the switch 205 to the switch 206 to the switch 207 to The lower ring is formed by the route of switch 208 to switch 204.

 In this configuration, in the upper ring, the switch 201 is a control switch. The control switch 201 closes the port 214 on one side and transmits the control frame 211 also on the other port 213. That is, the same control as in the case of a single ring configuration is performed. For the lower ring, the port 2 16 of one switch 208 out of the two switches 204, 208 connecting the rings is blocked, and the control frame 212 is transmitted from the port 215 of the switch 204 that is not blocked. The control frame 212 is monitored by the switch 208.

 That is, when two rings are connected and controlled, in the upper ring, one control switch performs port blocking and control frame transmission / reception, but the lower ring connects the rings. Two switches share port blocking and control frame transmission / reception. In the above example, the switch 204 is in charge of the control frame transmission function, and the switch 208 is in charge of the port blocking and control frame reception function.

 [0010] By configuring the ring of the lower arm J in this way, the route passing through the switches 204, 205, 206, 207, 208 can be monitored. When the control frame 212 is not received by the switch 208, the switch is switched on. By recognizing that a failure has occurred in the route from 204 to the switch 207 and releasing the blocking of the port 216 of the switch 208, the route can be switched without causing a loop route.

 Patent Document 1: Japanese Patent Application Laid-Open No. 2004-201009

 Patent Document 2: JP 2005-210279 A

 Non-Patent Document 1: IEEE 802. ID, 1998 Edition, pp. 58-109.

 Disclosure of the invention

Problems to be solved by the invention [0012] However, in the ring-type network control method composed of two rings disclosed in Patent Document 1, a failure has occurred and the normal ring can be used on the lower ring. Since the closed port to be provided exists in one of the two switches that connect the ring, the lower ring cannot communicate directly even between adjacent switches, and must pass through multiple switches. There is no case. In the example shown in FIG. 22, when the port 216 of the switch 208 is normally closed, communication between the adjacent switch 207 and the switch 208 is performed between the switch 207 to the switch 206 to the switch 205 to It must go through switch 204 to switch 208 and multiple switches. Therefore, when the amount of communication between the switch 207 and the switch 208 is large, an extra load is applied to the network as compared with the case where the switch 207 and the switch 208 communicate directly.

 [0013] In addition, in the lower ring when the above-described failure does not occur, the switch having the port closing function is limited to one of the two switches that connect the ring. This is the same when the number of rings to be connected further increases. In other words, in the construction of a ring network with multiple rings, the position of the switch that closes the port under normal conditions is subject to topological restrictions, and flexibility in constructing the network is lacking.

 In the configuration shown in FIG. 22, the closed port provided in the lower ring in the normal state is not the port 216 of the switch 208, and, for example, no loop path is generated as either port of the switch 206. In other words, in the lower ring, if the switch that closes the port under normal conditions is a switch other than the ring connection part, the topological restriction can be eliminated, and an extra load is applied to the above network. Can also be eliminated.

In this case, in the example shown in FIG. 22, in the lower ring, each control switch can perform port blocking and control frame transmission / reception in the same manner as the upper ring. Network in which the control is the same control mode. However, if the control method for the upper ring disclosed in Patent Document 1 is similarly applied to the lower ring, there is a problem in that a loop path may be formed depending on the location of the failure. This will be described below with reference to FIGS. 23 and 24. FIG. 23 is a diagram for explaining a normal control method in a ring network in which two rings configured by applying the prior art are connected. Figure FIG. 24 is a diagram for explaining a switching method when a failure occurs in the ring network shown in FIG.

 In FIG. 23, in the configuration shown in FIG. 22, the upper ring remains unchanged, and the control switch 201 closes the port 214 on one side and transmits the control frame 211 from the other port 213. In the lower ring, the switch 206 is used as a control switch, and the case where the control switch 206 performs port blockage and transmission / reception of the control frame 212 in place of the switches 204 and 208 constituting the ring connecting portion is shown. That is, the control switch 206 closes the port 217 on one side and transmits the control frame 212 from the other port 218. The switches 204 and 208 that constitute the ring coupling unit perform only the relay transfer of the control frame 212 in the same manner as the other switches in the lower ring.

 However, in such a configuration, as shown in FIG. 24, when a failure occurs in the common transmission line (link) connecting the switches 204 and 208, the control switch 201 sets the control frame 211 to the port 214. Since it is not possible to receive it, the blocked state of port 214 is released. In addition, the control switch 206 also cannot receive the control frame 212 at the port 217, so the blocked state of the port 217 is released. As a result, as shown by a dotted line in FIG. 24, a loop path 220 connecting all the switches is generated. This indicates that a broadcast 'storm will occur.

 [0018] The present invention has been made in view of the above, and even if each ring to be connected is configured without fixing the position of the switch that closes the port in a normal state, each loop is not generated without generating a loop path. The purpose is to obtain a ring network with multiple rings that can monitor the soundness of the ring with the same control method and can prevent the occurrence of a loop path and switch the path even when a fault occurs.

 Means for solving the problem

[0019] In order to achieve the above-described object, the present invention is directed to a ring network in which a plurality of rings are connected in a form in which two switches belonging to two adjacent rings are connected to each other. In each ring composed of a plurality of switches, including one of the switches, one of the plurality of switches is located at the connection end of the ring and is set as a master switch that closes one port during normal operation. And belong to the two affiliation switches Switching priority for two rings is set, and in each ring, the master switch cycles the control frame for confirming continuity from both ports so that it circulates around its own ring and faces the opposite port. Means for detecting whether one or both of a switching request instruction and a switching unnecessary instruction are received instead of receiving the control frame for confirming the continuity, and the continuity confirmation Control frame force received instead of the control frame for the control frame When only the control frame instructing that switching is not required, the block state of one port is maintained while the control frame instructing the switching request is included Releases the blocked state of one of the ports, flushes the MAC address learning table of its own switch, and MAC address learning tables from both ports. Means for transmitting a control frame instructing the flushing of the table, and in each ring, the two belonging switches cannot receive the control frame for confirming the continuity, and sometimes block the faulty port. When the failure side port is a switch side belonging only to the ring, the non-failure side port transmits the switching request instruction control frame instead of the continuity check control frame, while the failure side When the port is the partner switch side belonging to two rings, the control frame for the switching request instruction according to the switching priority for the ring instead of the control frame for confirming the continuity from the non-failure side port Or a means for transmitting the control frame indicating the switching unnecessary instruction, and a flag of the MAC address learning table at the non-failure side port. Means for flushing the MAC address learning table of its own switch when a control frame instructing the host is received, and in each ring, each switch excluding the two belonging switches is the continuity confirmation transmitted by the master switch. Means for closing the faulty port when the control frame cannot be received, means for transmitting the control frame for the switching request instruction from the non-failure port instead of the control frame for confirming the continuity, And a means for flushing the MAC address learning table of the own switch when a control frame instructing flushing of the MAC address learning table is received at the non-failure side port.

According to the present invention, the master switch set at an arbitrary position in each ring is guided without blocking one port during normal operation, that is, without generating a loop route. It is possible to monitor the soundness of both the clockwise and counterclockwise transmission paths of the own ring with the same control method of periodically transmitting control frames for communication confirmation from both ports. When a failure occurs in a link belonging to two adjacent rings in each ring, two switch forces belonging to the two rings can receive a control frame for confirming continuity with each other. Therefore, the failure side port is blocked, and switching is performed on one ring according to the switching priority, and an instruction not to switch on the other ring is sent from the non-failing side port to the corresponding master switch. Even at times, it is possible to prevent the occurrence of a loop route and switch the route. As a result, a ring network with multiple rings can be flexibly constructed without being restricted by topology.

 The invention's effect

 [0021] According to the present invention, even if each ring to be connected is configured without fixing the position of the switch that closes the port during normal operation, the soundness of each ring can be controlled in the same manner without generating a loop path. It is possible to monitor and to prevent the occurrence of a loop route even when a failure occurs and to switch the route!

 Brief Description of Drawings

 FIG. 1 is a conceptual diagram showing a configuration (part 1) of a ring network in which two rings are connected according to Embodiment 1 of the present invention.

 FIG. 2 is a flowchart for explaining a control operation of the master switch shown in FIG.

 FIG. 3 is a flowchart for explaining a control operation of the slave switch shown in FIG.

 [FIG. 4] FIG. 4 is a diagram for explaining an operation of detecting a failure that has occurred in a link belonging to only one of the two rings shown in FIG.

 FIG. 5 is a diagram for explaining a switching operation for the detected link failure shown in FIG.

 [FIG. 6] FIG. 6 is a diagram illustrating a switching operation for a failure of a slave switch belonging to only one of the two rings shown in FIG.

[FIG. 7] FIG. 7 is a diagram for explaining the detection operation when a failure occurs in the links belonging to the two rings shown in FIG. [FIG. 8] FIG. 8 is a diagram for explaining the switching operation for the detected failure of the links belonging to both rings shown in FIG.

 [FIG. 9] FIG. 9 is a diagram for explaining the switching operation for the failure of the slave switch belonging to the two rings shown in FIG.

 [FIG. 10] FIG. 10 is a diagram for explaining a switching operation for a failure of a master switch belonging to one of the two rings shown in FIG.

 FIG. 11 is a conceptual diagram showing a configuration (part 2) of a ring network in which two rings are connected according to Embodiment 2 of the present invention.

 FIG. 12 is a conceptual diagram showing a configuration (part 3) of a ring network in which two rings are connected according to Embodiment 3 of the present invention.

 FIG. 13 is a diagram showing a case where a fault is recovered but a fault is switched in the ring network shown in the first embodiment as the fourth embodiment of the present invention.

FIG. 14 is a diagram for explaining a recovery switching operation for returning the state at the time of failure recovery shown in FIG. 13 to the original normal path state.

 FIG. 15 shows, as Embodiment 5 of the present invention, in the ring network shown in Embodiment 1, an Ethernet (registered trademark) OAM frame is used instead of the control frame for the master switch to confirm continuity. It is a figure explaining the control operation in the case of transmitting / receiving.

 [FIG. 16] FIG. 16 is a diagram for explaining the MEP and MIP settings for each switch in the control operation using the Ethernet (registered trademark) OAM frame shown in FIG.

 FIG. 17 is a conceptual diagram showing a configuration (part 1) of a ring network in which three rings are connected according to Embodiment 6 of the present invention.

 FIG. 18 is a conceptual diagram showing a configuration (part 2) of a ring network in which three rings are connected according to Embodiment 7 of the present invention.

 FIG. 19 is a conceptual diagram showing a configuration (part 3) of a ring network in which three rings are connected according to an eighth embodiment of the present invention.

 [FIG. 20] FIG. 20 is a diagram for explaining a normal control method in a conventional ring network composed of one ring.

FIG. 21 is a diagram for explaining a failure switching method in the ring network shown in FIG. is there.

 FIG. 22 is a diagram for explaining a control method in a conventional ring network composed of a plurality of rings.

 FIG. 23 is a diagram for explaining a control method in a normal state in a ring network in which two rings configured by applying the conventional technology are connected.

 FIG. 24 is a diagram for explaining a switching method when a failure occurs in the ring network shown in FIG.

Explanation of symbols

 # 1, # 2, # 3 rings

 1 Master switch on ring # 1

 6 Master switch on ring # 2

 2, 3, 5, 7, 8, 9, 11, 12 Slave switch belonging to only one ring

 4, 10 Slave switches belonging to two rings, ring # 1 and ring # 2

 58, 61 Slave switch belonging to only one ring

 59, 60 A switch that belongs to two rings # 1 and # 2 and functions as a master switch for one ring and as a slave switch for the other ring

 64 Switch that belongs to two rings, ring # 1 and ring # 2, and functions as a master switch for one ring and the other ring

 72 Master switch on ring # 1

 81 Master switch on ring # 3

 77 Switch that belongs to two rings, ring # 2 and ring # 3, and functions as a master switch for ring # 2 and as a slave switch for ring # 3

 75, 85 Slave switch belonging to two rings, ring # 1 and ring # 2

 83 Slave switch belonging to two rings # 2 and # 3

 73, 74, 76, 78, 79, 80, 82, 84, 86. 87 Slave switch belonging to only one ring

94 Master switch on ring # 1 Master switch with 100 rings # 3

 107 Master Switch on Ring # 2

 98 Slave switch belonging to two rings, ring # 1 and ring # 2, and simultaneously belonging to two rings, ring # 2 and ring # 3, and belonging to three rings

 104, 108 Slave switches belonging to two rings

 95, 96, 97, 99, 101, 103, 105, 106, 109 Slave switch belonging to only one ring

 113 Master switch on ring # 1

 118 Master Switch on Ring # 2

 126 Master Switch on Ring # 3

 116, 122 Slave switches belonging to two rings, ring # 1 and ring # 2, and simultaneously belonging to two rings, ring # 2 and ring # 3, belonging to three rings

 114, 115, 117, 119, 120, 121, 123, 124, 125, 127, 128, 129 Slave switch belonging to only one ring

 BEST MODE FOR CARRYING OUT THE INVENTION

 [0024] Hereinafter, a preferred embodiment of a ring network according to the present invention will be described in detail with reference to the drawings.

 [0025] Embodiment 1.

 FIG. 1 is a conceptual diagram showing the configuration of a ring network according to Embodiment 1 of the present invention. In this first embodiment, in order to show the basic configuration of a ring network that is useful for the present invention, a ring network in which two rings (annular transmission lines) used as independent transmission lines are connected will be described. .

In FIG. 1, switches 1 to 12 are Ethernet (registered trademark) switches arranged on a ring. Of these, switch 4 and switch 10 each have three ports, one of which is directly connected to each other. Therefore, switch 1 to switch 2 to switch 3 to switch 4 to switch 10 to switch 11 to switch 12 to switch 1 ring # 1 and switch 6 to switch 7 to switch 8 to switch 9 to switch Ring # 2 is formed by the route from 10 to switch 4 to switch 5 to switch 6. Each of the switches 1 to 12 has a MAC address learning table, and each time an Ethernet (registered trademark) frame is received in the ring to which it belongs, a combination of a MAC address and a port based on the transmission source address. Learn and update. An aging time is set in the MAC address learning table, and when the aging time elapses, the learned entry disappears. In general, until the aging time elapses, communication with each other cannot be made! /.

 [0028] In each of such rings # 1 and # 2, one switch placed at an arbitrary position in the ring is in the connection end position of the ring and monitors the soundness of the ring to which it belongs. Switch (hereinafter referred to as “master switch”). This master switch transmits / receives control frames but does not transmit / receive user frames during normal operation on one of the ports on the clockwise transmission path side or counterclockwise transmission path side of the ring to which the master switch belongs. A port having a blocking function (this is referred to as an “edge port”) is formed, and the other port is configured as a port not having a blocking function (this is referred to as a “master port”). Then, the remaining switches notify the master switch when it detects a failure so that the master switch can perform the necessary control operations in the event of a failure, and switches that support the master switch ring health monitoring (hereinafter referred to as “slave”). It is set as “Switch”.

 In the example shown in FIG. 1, in ring # 1, for example, switch 1 is configured as a master switch, and the remaining switches 2, 3, 4, 10, 11, and 12 are each configured as a slave switch. ing. In ring # 2, for example, switch 6 is configured as a master switch, and the remaining switches 4, 5, 7, 8, 9, 10 are each configured as a slave switch. Since switch 4 and switch 10 are slave switches belonging to both rings, they are listed in two stages as “slave and slave”.

[0030] In FIG. 1, master switch 1 in ring # 1 is a slave switch 2 side port (port in the counterclockwise transmission path side in the arrangement shown in FIG. 1) 13 is a master port, and slave switch 1 It is assumed that the switch 12 side port (clockwise transmission line side port in the arrangement shown in FIG. 1) 14 is an edge port. Master switch 6 in ring # 2 is a slave Switch 7 side port (counterclockwise transmission line side port in the arrangement shown in Fig. 1) 15 is the master port, and slave switch 5 side port (clockwise transmission line side port in the arrangement shown in Figure 1) 16 Is an edge port. Note that the black circles indicated by the edge ports 14 and 16 indicate the closed state. Therefore, in the following explanation, a white circle ◯ indicates that the blockage is released.

Here, the “master switch” is different from the control switch in the prior art (Patent Document 1) in that the control switch in the prior art changes the control frame from a port having no blocking function to a port having a blocking function. On the other hand, the “master switch” transmits a control frame from a master port having no blocking function to an edge port having a blocking function and has a blocking function. The edge port does not have a blocking function, and is sent to the master port to monitor the soundness of the transmission path on both the clockwise and counterclockwise sides. The control frame used for monitoring the soundness is referred to herein as a “control frame for confirming continuity (abbreviated control frame for confirming continuity)”.

 That is, as shown in FIG. 1, during normal operation in which the ring is healthy, master switch 1 in ring # 1 cycles control frame 17 for continuity confirmation from master port 13 to edge port 14. The control frame 18 for confirming the continuity is periodically transmitted from the edge port 14 to the master port 13. Slave switches 2, 3, 4, 10, 11, and 12 in ring # 1 relay and transfer control frames 17 and 18 for confirming continuity, respectively.

 In addition, master switch 6 in ring # 2 periodically transmits continuity confirmation control frame 19 from master port 15 to edge port 16, and also transmits continuity confirmation control frame 20 to edge port 16. Is sent periodically to master port 15. The slave switches 4, 5, 7, 8, 9, and 10 in ring # 2 relay and transfer control frames 19 and 20 that confirm continuity, respectively.

When each slave switch detects the occurrence of a failure in which the control frame for confirming continuity to be relayed cannot be received in the above-described relay transfer process, each slave switch notifies the master switch. The master switch can detect the occurrence of a failure when it cannot receive the continuity check control frame transmitted so as to go around the ring. Upon receiving the above-mentioned failure occurrence notification, the necessary control operations are started! /

 [0035] The failure that occurs may or may not affect the other rings, and may affect both rings # 1 and # 2. The former failure includes the failure of the slave switch itself belonging to only one ring and the failure of the transmission line (link) connecting between the slave switches belonging to only one ring. In addition, as the latter failure, there are a failure in the switch itself belonging to both rings and a failure in a link common to both rings connecting the switches belonging to both rings.

 [0036] Each slave switch cannot receive the continuity confirmation control frame. The cause is the link failure force when the signal is not physically reachable, such as fiber breakage or cable breakage. Although it is possible to detect the failure of the adjacent switch itself that cannot receive the power continuity confirmation control frame, the master switch is notified if the continuity confirmation control frame cannot be received regardless of the force of the failure point. Come on! /

 [0037] When a failure occurs that does not affect other rings, the slave switch that detects the occurrence of the failure in the failed ring is referred to as a control frame for instructing a switching request, or a control frame for a switching request for short. The master switch is notified of the occurrence of a fault using the control frame that is displayed.

 [0038] On the other hand, the fault affecting both rings # 1 and # 2 is the power detected by either or both of the two slave switches belonging to both rings. In this case as well, a fault occurrence notification is sent to the master switch. If only the control frame for the switching request is used, a loop path 220 as shown in FIG.

 [0039] Therefore, as a measure against a failure that affects both rings # 1 and # 2, path switching is performed on one of the rings, and path switching is performed on V or the other ring. In addition, the “switching priority” is set for each of the two slave switches belonging to both rings. In the example shown in Fig. 1, the switching priority is set for the slave switches 4 and 10 belonging to both rings. For example, assume that ring # 1 is set with a switching priority “high” and ring # 2 is set with a switching priority “low”.

[0040] Here, the control frame used to request the master switch to perform path switching is the control frame having the same name as the control frame of the switching request described above. Master switch A control frame used for a request for not performing path switching is called a control frame for instructing that switching is not required, or a control frame for which switching is not required.

 [0041] In order to enable implementation of such "switching priority", the slave switches 4 and 10 recognize to which ring the control frame for continuity confirmation received and relayed forward belongs. I can do it. For example, in Rings # 1 and # 2, a virtual LAN (VLAN) is set up so that the control frame for confirming the continuity of each ring goes around, and the VLAN ID (identifier) is the ring # 1 and the ring. # 2 is different from the value.

 [0042] Next, referring to FIG. 2 and FIG. 3, the operation contents of the master switch and slave switch of both rings are outlined, and then specific fault switching operation is described with reference to FIG. 4 to FIG. explain. FIG. 2 is a flowchart for explaining the control operation of the master switch. FIG. 3 is a flowchart for explaining the control operation of the slave switch. In FIG. 2 and FIG. 3, the step indicating the processing procedure is abbreviated as ST.

 [0043] In FIG. 2, the master switches of both rings automatically transmit (ST1) a continuity confirmation control frame from the master port and the blocked edge port during normal operation. Repeated within the period when the continuity confirmation control frame transmitted so as to go round is received (ST2: Yes). Figure 1 shows a healthy state in which the control frame for confirming this continuity can be transmitted and received.

 [0044] In this ring healthy state, when one master switch or both master switches cannot receive the continuity confirmation control frame related to the transmission of its own switch (ST2: No), the reason for the failure is (Ml) There are cases where it occurs in one ring and does not affect other rings, and (M2) it may affect two rings, but depending on which reason the master switch that detected the failure Whether it is a failure is unknown. The master switch that detected the occurrence of a fault uses a control frame (control frame for switching request, control frame that does not require switching, control frame for both switching request and switching not required) instead of the control frame for confirming continuity from the slave switch. Until the continuity confirmation is received, the transmission of the control frame for confirming continuity is continued, and when the slave switch power receives the control frame described above instead of the control frame for confirming continuity, the corresponding control operation is performed.

[0045] (Ml) Assuming that the failure occurred in one ring and does not affect other rings For example, there are cases as shown in FIGS. The slave switch that detects the occurrence of a failure transmits the switching request control frame instead of the continuity confirmation control frame, so that when the master switch receives the switching request control frame, the master switch releases the blocking state of the edge port. Flush (clear) the MAC address learning table of its own switch (ST3). Then, the master switch transmits a control frame instructing flushing of the MAC address learning table from the master port and the edge port whose block has been released to the slave switch in its own ring (ST4).

 [0046] Thereby, the master switch and the healthy slave switch in the ring in which the failure has occurred can flush the MAC address learning table without waiting for the aging time to elapse, and can communicate on a new route. Note that a user frame with a destination address that does not have an entry in the MAC address learning table is broadcast to all ports other than the receiving port, so power communication with increased traffic becomes possible.

 [0047] (M2) Examples of the case where the failure that has occurred affects the two rings include the cases shown in FIGS. In these cases, switching priority is applied to the two rings, so the master switch performs three types of control operations depending on whether the failure that occurred is a common link failure or a failure in one switch. .

 [0048] When a failure occurs in the common link belonging to both rings (see Figs. 7 and 8), the master switch belonging to the ring to which the high switching priority is applied confirms the continuity of the control frame of the switching request. Therefore, the edge port blocking state is released and the MAC address learning table of its own switch is flushed (ST5). Then, the master port, the edge port that released the block, and the force also transmit a control frame instructing to flush the MAC address learning table (ST6). On the other hand, the master switch belonging to the ring to which the low switching priority is applied receives the control frame that does not require switching instead of the control frame for confirming the continuity, and therefore maintains the closed state of the edge port (ST7). In other words, route switching is not performed in the ring to which the low switching priority is applied.

[0049] When a failure occurs in one of the two slave switches belonging to both rings (see Fig. 9), the master switch belonging to the ring to which the high switching priority is applied is Since the control frame is received instead of the control frame for continuity confirmation, ST5 and Performs ST6 operation. On the other hand, the master switch belonging to the ring to which the low switching priority is applied receives both the switching request and the switching unnecessary control frame instead of the control frame for confirming the continuity. I do. That is, the blocked state of the edge port is released, and the MAC address learning table of the own switch is flushed (ST8). Then, a control frame for instructing flushing of the master port, the released edge port, and the force MAC address learning table is transmitted (ST9). That is, in this case, path switching is performed also in the ring to which the low switching priority is applied.

 [0050] Next, in FIG. 3, each slave switch of each ring can receive a control frame for confirming transmission path force continuity on both the clockwise and counterclockwise sides (ST11: Yes). Repeat the relay transfer (ST12). Figure 1 shows this situation. In the process of relay transfer, if a failure that cannot receive a control frame for confirming continuity occurs (ST11: No), the slave switch that detected the failure blocks the port on the failure side (ST13). . The slave switch that detects the failure performs the operation of ST14 to ST16 if it is a switch in the (S1) ring, and (S2) if it is a switch that belongs to both rings, ST17 to ST20. Perform the action.

 [0051] That is, (S1) If the slave switch that detects the failure does not belong to any other ring in the ring, a switch request control frame is transmitted instead of the continuity confirmation control frame (ST14). When the control frame for instructing the master switch force flush is received (ST15: Yes), the MAC learning table of its own switch is flushed accordingly (ST16). This is, for example, the case shown in FIGS. On the other hand, if no control frame for instructing flash is received from the master switch (ST15: No), the process ends without doing anything. This is the case shown in FIG. 10, for example.

[0052] Also, (S2) if the slave switch that detected the failure is a switch that belongs to both rings, first, the switching priority of the failed ring is determined (ST17). As a result, if the switching priority of the failed ring is “high” (ST17: Yes), the switch request control frame is confirmed to be connected to the master switch belonging to the ring with the high switching priority. Is sent instead of the control frame (ST18), and the MAC learning table of the switch is flushed according to the control frame instructing the flush to receive the master switch power ( ST19). On the other hand, if the failed ring has a low switching priority (ST17: No), the continuity confirmation of the control frame that does not require switching is performed for the master switch belonging to the ring with the low switching priority. Transmit in place of the control frame (ST20), and the MAC learning table of the own switch is flushed according to the control frame instructing the flush to receive the master switch force (ST19). This is, for example, the case shown in FIGS.

Next, a specific failure switching operation will be described with reference to FIGS. As a result, it will be clarified that a loop route does not occur even if a failure occurs and the route is switched.

 [0054] A) Switching operation for failure of link belonging to only one ring (Fig. 4, Fig. 5)

 FIG. 4 is a diagram for explaining the operation of detecting a failure that has occurred in a link belonging to only one of the two rings. FIG. 5 is a diagram for explaining the switching operation for the detected link failure shown in FIG.

 [0055] As shown in FIG. 4, in the healthy state of both rings shown in FIG. 1, for example, if a failure 21 occurs in the link between slave switches 4 and 5 in ring # 2, the master of ring # 2 In switch 6, control frames 19 and 20 for confirming continuity transmitted from master port 15 and edge port 16 cannot reach each other's ports. Master switch 6 is able to recognize that a failure has occurred because it cannot receive control frames 19 and 20 to confirm continuity Slave switch power that does not release blockage of edge port 16 The blockage remains maintained until the control frame arrives.

 [0056] When one of the continuity confirmation control frames 19 and 20 cannot be received by the slave switches 4 and 5, and the occurrence of the failure 21 is detected, as shown in FIG. 5, the slave switch 5 The side port 23 is blocked, and the slave switch 4 also blocks the failure side port 24 in the same manner. As a result, path switching that avoids the failure 21 is performed, and generation of a loop path is prevented.

[0057] Then, the slave switch 5 transmits the control frame 25 for switching request from the non-failure side port to the master switch 6 instead of the control frame 19 for confirming the continuity received and relayed before the failure occurred. To do. Similarly, the slave switch 4 receives and relays it before the failure occurs, and instead of the control frame 20 for confirming the continuity, the control frame for the switching request 26 is sent to the master switch 6 from the non-failed port. As a result, each switch after the slave switches 4 and 5 in the ring # 2 receives the control frames 25 and 26 for the switching request even if it does not receive the control frames 19 and 20 for confirming the continuity. It is not judged that a failure has occurred.

 The master switch 6 receives the switching request control frames 25 and 26. The master switch 6 releases the block of the edge port 16 in accordance with one of the switching request control frames received first. When master switch 6 releases blockage of edge port 16, it flushes the MAC address learning table of its own switch, and at the same time controls frame 27 that instructs master port 15, edge port 16, and flush of the MAC address learning table. , 28 is sent. Each slave switch that receives the control frames 27 and 28 instructing the flush flushes its own MAC address learning table. As a result, the path switching is completed before the aging time elapses, and in the example shown in FIGS. 4 and 5, the slave switch 5 is not isolated and can communicate with other switches.

 [0059] For example, if the MAC address learning table of slave switch 5 is set to output to the port on the side of slave switch 4 when communicating with slave switch 9 before a failure occurs (Fig. 4), When the failure 21 occurs and the port blocking state changes as shown in FIG. 5, the slave switch 5 needs to output a user frame to the slave switch 9 to the master switch 6 side. Even when slave switch 9 sends a user frame to slave switch 5, it is necessary to output it to the slave switch 8 side instead of the slave switch 10 side. Since the above-described path switching is performed, such a necessary path is formed between the slave switch 5 and the slave switch 9, and communication between them is continued without any trouble.

 [0060] Note that, as described above, a user frame having a destination address for which there is no entry in the MAC address learning table is broadcast to all ports other than the reception port, so that power communication with increased traffic is possible. Note that failure # 21 on ring # 2 side does not affect ring # 1 side, so ring # 1 side will continue to operate as normal.

[0061] B) Switching operation for failure of slave switch belonging to only one of the two rings (Fig. 6) As shown in Fig. 6, in the state in which both rings are healthy as shown in Fig. 1, for example, when a failure occurs in slave switch 3 belonging to ring # 1, adjacent slave switches 2 and 4 Because it becomes impossible to receive, the failure is detected. Therefore, the slave switches 2 and 4 block the failure side ports 29 and 30 that are the ports on the slave switch 3 side as described with reference to FIG. Send control frames 31 and 32 to master switch 1 from the non-failed port.

 [0062] Master switch 1 releases the blocking of edge port 14 in accordance with the control frame of the switching request received first, as described with reference to FIG. Then, the MAC address learning table of its own switch is flushed, and control frames 33 and 34 instructing flushing are transmitted from both the master port 13 and the edge port 14.

 Thereby, each slave switch in ring # 1 completes the path switching by flushing its own MAC address learning table. As described above, even when a slave switch that belongs to only one ring fails, the path is switched by the same operation as when a link that belongs to only one ring fails (Fig. 5). In ring # 2, the failure of slave switch 3 is not affected, so the same operation as in the normal state is performed.

 [0064] C) Switching operation for failure of link belonging to two rings (Fig. 7, Fig. 8)

 Fig. 7 illustrates the detection operation when a failure occurs in a link belonging to two rings, and Fig. 8 illustrates the switching operation for the failure of a link belonging to both rings shown in Fig. 8. FIG. When a failure occurs in a link belonging to two rings, a loop path is formed in the conventional technology as described in FIG. 24. In this embodiment, however, a switching operation based on the switching priority is performed. As a result, a loop path is not formed.

[0065] As shown in FIG. 7, in the state where both rings are healthy as shown in FIG. 1, if a failure 35 occurs in the link between the slave switches 4 and 10 belonging to the two rings, the slave switch 4 10 detects that the failure 35 has occurred in the common link because it cannot receive the control frame for confirming the continuity. Therefore, the slave switches 4 and 10 block the opposing failure side ports 36 and 37 and determine the switching priority. As described above, the switching priority is “high” for ring # 1 and “low” for ring # 2. [0066] Therefore, slave switch 4 transmits control frame 38 for switching request from the non-failure side port to ring # 1 side instead of control frame 18 for confirming continuity to master switch 1, and ring # 2 side. Instead of the control frame 19 for confirming the continuity to the master switch 6, a control frame 40 that does not require switching is transmitted from the non-failure side port. The slave switch 10 transmits a control frame 39 for switching request from the non-failure side port to the master switch 1 on the ring # 1 side instead of the control frame 17 for confirming the continuity, and the master switch 6 on the ring # 2 side. In response to this, a control frame 41 that does not require switching is transmitted from the non-failure side port instead of the control frame 20 for confirming continuity.

 [0067] Master switch 1 on the ring # 1 side receives only control frames 38 and 39 of the switching request. Master switch 1 releases the blocking of edge port 14 according to the control frame of the switching request received first, flushes the MAC address learning table of its own switch, and controls flushing from master port 13 and edge port 14 Send a frame. As a result, the path is switched in each switch of ring # 1.

 [0068] On the other hand, the master switch 6 on the ring # 2 side receives only the control frames 41 and 42 that do not require switching, and does not receive any switching request control frames, so that the edge port 16 remains blocked. Keep it. Since master switch 6 no longer receives control frames 19 and 20 for confirming continuity, it recognizes that some kind of fault has occurred.By receiving control frames 41 and 42 that do not require switching, the master switch 6 receives other frames. Judge that ring # 1 is switching the route in case of failure.

 [0069] As described above, when a switching priority is set for slave switches 4 and 10 belonging to two rings, and a failure occurs in a link belonging to two rings, a ring with a high switching priority is used. Since the path switching is performed and the path switching is not performed on the ring with the low switching priority, the path switching can be performed without generating a loop path even when a failure occurs in the link belonging to the two rings. Is possible.

 [0070] D) Switching operation for failure of slave switch belonging to two rings (Figure 9)

As shown in Fig. 9, in the state where both rings are healthy as shown in Fig. 1, if a failure occurs in slave switch 4, for example, of slave switches 4 and 10 belonging to two rings, the adjacent slave switch 3, 5, and 10 receive the control frame for continuity confirmation. Detects the occurrence of a failure. Therefore, the slave switch 3 closes the failure side port 44, the slave switch 5 closes the failure side port 45, and the slave switch 10 closes the failure side port 37.

 [0071] Since the switching priority of the slave switch 3 is not set in both ring affiliation switches, the control switch 18 for confirming the continuity with respect to the master switch 1 is used in the same way as when a normal failure occurs. The control frame 46 of the switching request is transmitted to Similarly, slave switch 5 does not have a switching priority over both ring affiliation switches, so instead of control frame 19 for confirming continuity with respect to master switch 6, as in the case of normal failure. A control frame 49 of the switching request is transmitted from the non-failed port.

 [0072] On the other hand, slave switch 10 is a switch belonging to both rings, and ring # 1 is set as a high switching priority and ring # 2 is set as a low switching priority. A switch request control frame 47 is sent from the non-failure side port to switch 1 instead of the continuity check control frame 17, and the continuity check control frame 20 is sent to the master switch 6 on the ring # 2 side. Send control frame 48 that does not require switching from the non-failed port

[0073] In this case, the master switch 1 on the ring # 1 side receives the switching request control frame 46 from the slave switch 3, and receives the switching request control frame 47 from the slave switch 10. As described above, the block of the edge port 14 is released, the MAC address learning table of the own switch is flushed, and the control frames 50 and 51 instructing flushing are transmitted from the master port 13 and the edge port 14.

On the other hand, the master switch 6 receives the control frame 49 of the switching request from the slave switch 5 and receives the control frame 48 of which switching is not required from the slave switch 10 The control frame of the switching request and the control frame of which switching is not required Then, the control frame of the switch request is more important. Therefore, when master switch 6 receives control frame 49 for the switching request, it releases the blocking of edge port 16, flushes its own MAC address learning table, and instructs flush from edge port 16 and master port 15. Yes Send control frames 52 and 53. This can prevent the slave switch 5 from being isolated and unable to communicate. [0075] As described above, even if a failure occurs in one of the two slave switches belonging to the two rings, a loop path is not generated and an isolated slave switch is not generated. It is possible to perform route switching.

 [0076] E) Switching operation for the failure of the master switch belonging to one of the two rings (Fig. 10)

 FIG. 10 is a diagram for explaining the switching operation for the failure of the master switch belonging to one of the two rings. Figure 10 shows the case where a failure occurred in master switch 1 on the ring # 1 side. In this case, the failure of master switch 1 is not affected in ring # 2, so the same operation as in the normal state is performed.

[0077] As shown in FIG. 10, in the state where both rings are healthy as shown in FIG. 1, when a failure occurs in the master switch 1 on the ring # 1 side, the adjacent slave switches 2 and 12 are controlled to check the continuity. Since no frame is received, a failure is detected. Therefore, in the same operation as described above, the slave switch 2 closes the failure side port 55 and the slave switch 12 closes the failure side port failure side port 54. Then, slave switch 2 sends a control frame 57 for switching request to master switch 1 from the non-failure side port, and slave switch 12 similarly sends a control frame 56 for switching request to master switch 1 on the non-failure side port. Send from.

 However, even if the control frames 57 and 56 of the switching request reach the master switch 1 after making a round of the ring # 1, since the master switch 1 is in a failure state, the path switching does not occur. At this time, since the route is not blocked between any two switches other than the master switch 1, communication is possible, and no loop route is generated. Therefore, even if master switch 1 or master switch 6 fails, the communication of other switches will not be affected!

 [0079] Embodiment 2.

 FIG. 11 is a conceptual diagram showing the configuration of a ring network according to the second embodiment of the present invention. In FIG. 11, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are assigned the same reference numerals. Here, the description will be focused on the part related to the second embodiment.

As shown in FIG. 11, the ring network according to the second embodiment is the same as that shown in FIG. In the configuration shown in state 1), master switch 1 is slave switch 58, and master switch 6 is slave switch 61. For the slave switch 4-force ring # 1, the switch (slave master switch) 59 functions as a slave switch for ring # 2, and functions as a master switch for ring # 2. Also, it becomes a master switch (master slave switch) 60 that functions as a master switch for the slave switch 10-power ring # 1, and functions as a slave switch for ring # 2.

 [0081] In the configuration shown in FIG. 11, in ring # 1, the master function unit of switch 60 is a master port that does not have a blocking function on the common link side port that belongs to the two rings. The side port becomes an edge port 63 having a blocking function, and the control frames 17 and 18 for continuity confirmation shown in FIG. 1 can be transmitted and received in the same manner.

 [0082] In ring # 2, the master function unit of switch 59 is a master port that does not have the blocking function on the common link side port belonging to the two rings, and the port on the slave switch 5 side has the blocking function. Thus, the continuity confirmation control frames 19 and 20 shown in FIG. 1 can be transmitted and received in the same manner.

 [0083] Then, in the switches 59 and 60 that belong to the two rings and have the master function and the slave function, the switching priority is set based on the same idea as in the first embodiment.

 [0084] In this way, an Ethernet (registered trademark) switch belonging to only one ring is not used as a master switch. A master function and a slave are respectively connected to two Ethernet (registered trademark) switches belonging to two rings. Even in the configuration that bears the functions, all the controls described in the first embodiment can be performed in the same manner. Therefore, path switching can be performed without generating a loop path even when a failure occurs.

 [0085] Embodiment 3.

 FIG. 12 is a conceptual diagram showing the configuration of a ring network according to the third embodiment of the present invention. In FIG. 12, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are assigned the same reference numerals. Here, the description will focus on the parts related to the third embodiment.

As shown in FIG. 12, in the ring network according to Embodiment 3, in the configuration shown in FIG. 1 (Embodiment 1), master switch 1 becomes slave switch 58, and master switch Tsuchi 6 is the slave switch 61. Then, slave switch 10 becomes slave switch 10 that changes slave switch 4 as a master switch for both ring # 1 and ring # 2 (master master switch) 64! /.

 [0087] In the configuration shown in FIG. 12, in ring # 1, the ring # 1 side master function unit of switch 64 is a master port in which the common link side port belonging to the two rings does not have a blocking function. The switch 3 side port becomes an edge port 66 having a blocking function, and the control frames 17 and 18 for confirming conduction shown in FIG. 1 can be transmitted and received in the same manner.

 [0088] Also, in ring # 2, the ring # 2 side master function section of switch 64 is a master port that does not have a blocking function on the common link side port belonging to the two rings, and on the slave switch 5 side. The port becomes an edge port 62 having a blocking function, and the continuity confirmation control frames 19 and 20 shown in FIG. 1 can be similarly transmitted and received.

 [0089] Then, switching priority is set to switch 64 and slave switch 10 that belong to two rings and serve as master switches for both sides in the same manner as in the first embodiment. .

 [0090] In this way, an Ethernet (registered trademark) switch belonging to only one ring is not used as a master switch. One of two Ethernet (registered trademark) switches belonging to two rings is connected to both rings. Even in a configuration in which the master switch is used and the other is a slave switch in both rings, all the controls described in the first embodiment can be performed in the same manner. Therefore, path switching can be performed without generating a loop path even when a failure occurs.

In short, when two rings are connected and controlled as a single ring network, Embodiments 1 to 3 are as follows with respect to the arrangement positions of switches that perform port blocking and transmission / reception of control frames under normal conditions. It shows that. In other words, using rings # 1 and # 2 above, the prior art (Patent Document 1) uses a switch that performs port blocking and control frame transmission / reception. However, in ring # 2, the force that must be provided at the position where the ring is connected, that is, the switch belonging to the two rings, is the embodiment of the present invention. As can be seen from Fig. 3, ring # 2 also shows that it can be placed at any position within ring # 2. In other words, there are no topological constraints that were problematic in the prior art (Patent Document 1). It is possible to flexibly construct a ring network with multiple rings (see Figure 17 to Figure 19).

 [0092] Since the switching priority is set for the switches belonging to the two rings, a loop route is not generated regardless of the position of the link or the position of the switch. It is possible to perform fault switching.

 [0093] Embodiment 4.

 In the fourth embodiment, with reference to FIG. 13 and FIG. 14, the recovery switching operation for returning to the original normal route state at the time of failure recovery will be described. FIG. 13 is a diagram showing a case where the fault is recovered but the fault is switched in the ring network shown in the first embodiment as the fourth embodiment of the present invention. FIG. 14 is a diagram for explaining the recovery switching operation for returning the state at the time of failure recovery shown in FIG. 13 to the original normal path state.

 FIG. 13 shows a state in which the link failure is recovered after switching to the link failure 21 shown in FIG. Even if the link failure is recovered, the master switch 6 is in a state in which the blockage of the edge port 16 is released, and the slave switches 4 and 5 maintain the failure side ports 23 and 24 in the blocked state, respectively. Even in this state, that is, even if the failure is recovered after failure switching, communication is still possible in the state of failure switching, so recovery switching is not necessarily required, but it must be returned to the path before the failure occurred. If you want, you can switch recovery as follows.

 That is, since the master switch 6 continues to transmit the continuity confirmation control frames 19 and 20 from the master port 15 and the edge port 16 in the failure switching state, when the failure is recovered, the continuity confirmation control is performed. Frames 19 and 20 can be received by slave switches 4 and 5 and master switch 6 to recognize failure recovery. Further, when the master switch 6 can receive the control frames 19 and 20 for confirming the continuity at both the master port 15 and the edge port 16, it can be determined that the failure has been recovered.

[0096] Therefore, when it is desired to return to the state before the failure switching, the master switch 6 automatically receives the control frames 19 and 20 for confirming the continuity at both the master port 15 and the edge port 16 and determines that the failure is restored. As shown in Fig. 14, the edge port 16 is returned to its original blockage state and the switch MAC Flush the address learning table. Then, the master switch 6 transmits a control frame 67 for releasing the blockage and flushing from the master port 15 to the edge port 16.

 Accordingly, the slave switch in the middle of receiving the control frame 67 for releasing the blockage and flushing checks whether or not the port of the switch is blocked, and releases the blockage if there is a blocked port. It also flushes its own switch MAC address learning table. In the example shown in FIG. 14, since the slave switches 4 and 5 block the port, when the control frame 67 is received, the block is released and the MAC address learning table of the switch is flushed. Further, when the slave switch 7, 8, 9, 10 receives this control frame 67, it flushes its own MAC address learning table.

 As described above, in the ring network according to the first to third embodiments, the recovery switching operation can be performed.

 [0099] Embodiment 5.

 In this fifth embodiment, referring to FIG. 15 and FIG. 16, an Ethernet (registered trademark) defined in ITU-T Y. 1731 is used instead of the control frame used in the first to fourth embodiments. ) An example of similar fault detection and path switching using an Ethernet (registered trademark) OAM frame conforming to the OAM (Operations, Administration and Maintenance) function will be described. FIG. 15 shows a case where the master switch transmits / receives an Ethernet (registered trademark) OAM frame instead of the control frame for confirming the continuity in the ring network shown in the first embodiment as the fifth embodiment of the present invention. It is a figure explaining this control operation. FIG. 16 is a diagram for explaining the MEP and MIP settings for each switch in the control operation using the Ethernet (registered trademark) OAM frame shown in FIG.

 [0100] In ITU-T Y. 1731, the ETH-CC function (Ethernet (registered trademark) Continuity Check) is defined for continuity confirmation, and a CCM (Continuity C heck Message) frame for confirming continuity with the opposite device is provided. Is defined. The CCM frame is periodically transmitted from a certain MEP (MEG End Point) to the opposite MEP. ME is an abbreviation for Maintenance-Entity. MEG is an abbreviation for Maintenance 'Entity' Group

[0101] When setting the MEP, it is necessary to set the MEG level and the opposite MEP. CCM The MEG level information is contained in the frame, and the CCM frame is only terminated at the opposite MEP set to the same MEG level. In the lower MEG level MEP, the upper MEG level CCM frame is It is not terminated and is passed through.

Therefore, in Embodiments 1 to 4, it is possible to detect the occurrence of a failure by not receiving the control frame for continuity confirmation by the slave switch, but instead of the transmission / reception function of the control frame for continuity confirmation. If the MEP that transmits and receives CCM frames is set as it is as the master port and edge port of the master switch, the slave switch in the middle only passes through the CCM frame, so failure detection by non-reception of the CCM frame cannot be detected. .

 [0103] Therefore, in the fifth embodiment, when a CCM frame that is a control frame compliant with the Ethernet (registered trademark) OAM function is used, as shown in Fig. 16, the master port and the edge port of the master switch are used. Set the MEP of the upper MEG level to and the lower MEG level MEP and MIP (MEG Intermediate Point) of the upper MEG level to each switch. By setting the MEP in this way, as shown in Fig. 15, it is possible to transmit and receive CCM frames 68 and 69 at the upper MEG level and CCM frames 70 and 71 at the lower MEG level, and to detect a failure. Can do.

 FIG. 16 shows the MEP setting and MIP setting for each switch in ring # 1 shown in FIG. 15 as an example. As shown in Fig. 16, if a lower MEG level MEP and an upper MEG level MIP are set for each switch, the ETH-CC function does not receive a CCM frame at the lower MEG level MEP even if the CCM frame is not received. Ability to detect LOC (Loss of Continuity) failures ETH—Ethernet (registered trademark) Alarm Indication Signal (AIS) function sends a higher-level AIS frame from the MIP, so the master switch recognizes the failure. can do.

 [0105] However, when there is one ring, it is possible to use the AIS frame as a control frame for switching requests, but when there are two rings, a failure occurs in the common link connecting both rings. On the other hand, it is not necessary to switch on one ring, so AIS frames cannot be used.

[0106] Therefore, in this Embodiment 5, switching request, switching unnecessary, flush instruction, block release In each control frame, a VSM (Vendor Specific Message) frame defined in ITU-T V. 1731 is independently defined and used.

[0107] As described above, the CCM frame conforming to the Ethernet (registered trademark) OAM function defined in ITU-T Y. 1731 is used as the control frame for confirming the continuity, the VSM frame is requested to be switched, switching is not required, By using it as a control frame corresponding to each control frame for flush instruction and block release, a ring network with multiple rings can be configured in such a way that path switching can be performed without generating a loop path when a failure occurs. In addition, restoration switching can be performed in the same way.

 [0108] Embodiment 6.

 FIG. 17 is a conceptual diagram showing a configuration (No. 1) of a ring network in which three rings are connected according to Embodiment 6 of the present invention. In the sixth embodiment, a configuration example in which three rings are connected in a row in a ladder shape is shown.

 As shown in FIG. 17, in the ring network according to the sixth embodiment, ring # 1, ring # 2, and ring # 3 are connected in a row in a ladder shape. Ring # 1 is composed of a path from switch 72 to switch 73 to switch 74 to switch 75 to switch 85 to switch 86 to switch 97 to switch 72. Ring # 2 is composed of a route from switch 77 to switch 83 to switch 84 to switch 85 to switch 75 to switch 76 to switch 77. Ring # 3 includes a route of switch 81 to switch 82 to switch 83 to switch 77 to switch 78 to switch 79 to switch 80 to switch 81.

 [0110] In ring # 1, switch 72 is the master switch and edge port 88 is defined. Switches 75 and 85 belonging to ring # 1 and ring # 2 are switches that act as slave switches for both rings. Since the link connecting switch 75 and 85 is a common link belonging to ring # 1 and ring # 2, switch 75 and 85 are set with switching priority for ring # 1 and ring # 2, respectively. Being sung.

[0111] Of switches 77 and 83 belonging to ring # 2 and ring # 3, switch 77 is a master switch with edge port 89 defined for ring # 2, and a slave switch for ring # 3 It is a switch that acts as Switch 83 is a switch that acts as a slave to both rings # 2 and # 3. The link connecting switches 77 and 83 is , Ring # 2 and ring # 3 are common links, and therefore, switching priorities for ring # 2 and ring # 3 are set in switches 77 and 83, respectively.

[0112] In ring # 3, switch 81 is the master switch and edge port 90 is defined.

 [0113] In the above configuration, the control frame for continuity confirmation or the higher-level CCM frame in Ethernet (registered trademark) OAM flows through paths 91, 92, and 93 shown in FIG. If a failure in a link belonging to two rings or a failure in a switch belonging to two rings is detected, the ring is switched from the switch that detected the failure among the switches belonging to two rings. According to the priority, a control frame that does not require switching or switching, or a VSM frame that does not require switching or switching is transmitted.

 [0114] For a failure of a link belonging to two rings or a failure other than a failure of a switch belonging to two rings, use the control frame or VSM frame of the switch force switching request that detected the failure. Just send it. In the following, it goes without saying that switching control can be performed in a configuration in which three rings are connected by the same control as in the case of the two rings described in the first embodiment.

 [0115] In Fig. 17, force indicating a configuration in which three rings are connected in a ladder shape, even if a configuration in which four or more rings are connected in a ladder shape, if a switching priority is set for a switch belonging to two rings, The same switching can be performed by the same control as in the case of the two rings described in the first embodiment.

 [0116] Embodiment 7.

 FIG. 18 is a conceptual diagram showing a configuration (part 2) of a ring network in which three rings are connected according to Embodiment 7 of the present invention. In the seventh embodiment, a configuration example in which three rings are deployed and connected on the surface is shown.

As shown in FIG. 18, in the ring network according to the seventh embodiment, ring # 1, ring # 2 and ring # 3 are deployed and connected on the surface. Ring # 1 is composed of the route of switch 94 to switch 95 to switch 96 to switch 97 to switch 98 to switch 108 to switch 109 to switch 94. Ring # 2 consists of switch 107 to switch 108 to switch 98 to switch 104 to switch 105 to switch 106 to switch 107. It is made. Ring # 3 is composed of a path from switch 100 to switch 101 to switch 102 to switch 10 4 to switch 98 to switch 99 to switch 100.

[0118] In ring # 1, switch 94 is the master switch and edge port 110 is defined. In ring # 2, switch 107 is the master switch and edge port 111 is defined. In ring # 3, switch 100 is the master switch and edge port 112 is defined.

 [0119] Switch 108 is a switch that belongs to ring # 1 and ring # 2 and acts as a slave switch for both rings. Switch 104 is a switch belonging to ring # 2 and ring # 3 and acting as a slave switch for both rings. Switch 98 is a switch that belongs to ring # 1, ring # 2, and ring # 3 and acts as a slave switch for the three rings.

 [0120] In this case, the link connecting switches 108 and 98 is a common link belonging to ring # 1 and ring # 2. The link connecting switches 104 and 98 is a common link belonging to ring # 2 and ring # 3. Therefore, in the configuration shown in FIG. 18, a switch that belongs to two rings and a switch that belongs to three rings are mixed as shown in FIG. 17. Unlike the configuration, switch 1 08 is set to switch priority between ring # 1 and ring # 2, and switch 104 is set to switch priority between ring # 2 and ring # 3. For switch 98, the switch priority relationship between ring # 1 and ring # 2 set for switch 1 08 and switch 102 and the switch priority relationship between ring # 2 and ring # 3 Set.

 [0121] By setting the switching priority in this way, when a failure occurs in the common link belonging to ring # 1 and ring # 2, or the common link belonging to ring # 2 and ring # 3. If a failure occurs in the link, the corresponding switch 108, switch 98, and switch 102 switch the control frame for the switching request or the VSM for the switching request to the ring with the set high switching priority. By transmitting a frame and transmitting a control frame that does not require switching or a VSM frame that does not require switching to a ring with a low switching priority, the same as in the case of two rings described in Embodiment 1. Can be switched.

[0122] For links other than rings or failures other than switches, check the failure. A switch request control frame or a switch request VSM frame may be transmitted from the issued switch. Thereafter, it goes without saying that the switching control can be similarly performed by the same control as in the case of the two rings described in the first embodiment. Even when there are 4 or more rings, switching control can be performed in the same way by setting switching priority to each of multiple ring affiliation switches (2 switches) based on the same idea as above.

 [0123] Embodiment 8.

 FIG. 19 is a conceptual diagram showing a configuration (part 3) of a ring network in which three rings are connected according to Embodiment 8 of the present invention. In the eighth embodiment, a configuration example is shown in which three rings are arranged and connected so as to partially overlap!

 [0124] As shown in Fig. 19, the ring network according to Embodiment 8 is composed of ring # 1, ring # 2, and ring # 3, but ring # 2 and ring # 3 overlap. It is arranged in the form of.

 [0125] Ring # 1 is composed of the route of switch 113 to switch 114 to switch 115 to switch 116 to switch 1 22 to switch 123 to switch 124 to switch 113 !. Ring # 2 is composed of the route of switch 118 to switch 119 to switch 120 to switch 121 to switch 122 to switch 116 to switch 117 to switch 118. Ring # 3 is composed of a route from switch 126 to switch 127 to switch 128 to switch 129 to switch 122 to switch 116 to switch 125 to switch 126.

 [0126] In ring # 1, switch 113 is the master switch and edge port 130 is defined. In ring # 2, switch 118 is the master switch and edge port 131 is defined. In ring # 3, switch 126 is the master switch and edge port 132 is defined.

 [0127] Since switches 116 and 122 belong to ring # 1, ring # 2 and ring # 3 and act as slave switches for these three rings, switches 116 and 122 are connected to each other. The link to be linked is a common link belonging to ring # 1, ring # 2, and ring # 3.

[0128] Therefore, the switching priority is set for the switches 116 and 122. However, as shown in FIG. 19, in the configuration in which one link is common to the three rings, Re One of ring # 1, ring # 2, and ring # 3 is set as a high switching priority, and the other two rings are set as a low switching priority that is not distinct.

 [0129] By setting the switching priority in this way, when a common link failure occurs, the switches 116 and 122 switch the control frame for switching request or switching to one ring with high switching priority. By transmitting the requested VSM frame and transmitting the control frame that does not require switching or the VSM frame that does not require switching to the other two rings, there are two rings described in Embodiment 1. Similar switching control can be performed.

 [0130] For a failure other than a link or switch belonging to a common ring, a switch request control frame or a switch request VSM frame may be transmitted from the switch where the failure is detected. Thereafter, it goes without saying that the switching control can be similarly performed by the same control as in the case of the two rings described in the first embodiment. Even in the case of the ring force or higher, there is only one link common to all rings, so there is only one ring switch (two switches), but the switching priority should be set in the same way as above. In the same way, switching control can be performed.

 Industrial applicability

 [0131] As described above, the ring network according to the present invention can monitor the health of each ring by the same control method without generating a loop path when each ring to be connected is normal, and when a failure occurs. However, it is useful for flexibly constructing a ring network with multiple rings that can prevent the occurrence of loop paths and perform path switching without being restricted by topology.

Claims

The scope of the claims  In a ring network where multiple rings are connected in the form of two switches belonging to two adjacent rings,  In each ring composed of a plurality of switches including the two belonging switches, one of the plurality of switches is located at the connection end of the ring, and one port is closed during normal operation. In addition to being set as a master switch, the switching priority for the two belonging rings is set for the two belonging switches.  For each ring, the master switch periodically transmits a control frame for confirming continuity from both ports around its own ring to the opposite ports so as to confirm the continuity. In place of receiving the control frame, means for detecting whether or not the control frame for receiving one or both of the switching request instruction and the switching unnecessary instruction is received and the control frame for confirming the continuity are received. When only the control frame indicating that the control frame force switching is not required, the blocked state of the one port is maintained, while when the control frame instructing the switching request is included, the blocked state of the one port is released. Flush the MAC address learning table of its own switch, and send a control frame to instruct the MAC address learning table to be flushed from both ports. And a means to,  In each ring, the two belonging switches are means for closing the faulty port when the control frame for confirming the continuity cannot be received, and when the faulty port is the switch side belonging to only the ring. Transmits the control frame for the switching request instruction instead of the control frame for confirming the continuity from the non-failure side port, while the non-failure side when the faulty port is the partner switch side belonging to two rings. Means for transmitting from the port the control frame for the switching request instruction according to the switching priority for the ring instead of the control frame for confirming the continuity or the control frame for the switching unnecessary instruction, and the non-failed side When a control frame indicating flush of the MAC address learning table is received at the port, the MAC address of the switch itself And a means to flush the learning table, Each switch, except the two belonging switches, has a master switch. Means for blocking the faulty port when the control frame for confirming continuity to be transmitted cannot be received, and transmitting the control frame for the switching request instruction from the non-failure side port instead of the control frame for confirming continuity Means and the non-failed port Means for flushing the MAC address learning table of the switch when a control frame instructing flushing of the MAC address learning table is received.  A ring network characterized by that. [2] In each ring, the master switch  When the blocking of one port is released, if recovery from failure can be confirmed by receiving control frames for confirming continuity from both ports, the one port is returned to the blocking state and both ports are closed. A means for transmitting a control frame instructing release from the port,  Each switch other than the master switch in each ring is  2. The device according to claim 1, further comprising means for releasing the blocking when there is a port blocking the state of the port of the own switch when receiving the control frame instructing the release of the blocking. Ring network. [3] In each ring, the master switch  In the case where the blocking of the one port is released, if failure recovery can be confirmed by receiving control frames for confirming continuity from both ports, means for notifying the outside of the failure recovery and recovery from the outside When a switching instruction is input, the one port is returned to a blocked state, and a control frame is transmitted from both ports for instructing to release the blocking.  Each switch other than the master switch in each ring is  2. The device according to claim 1, further comprising means for releasing the blocking when there is a port blocking the state of the port of the own switch when receiving the control frame instructing the release of the blocking. Ring network. [4] In a ring network where multiple rings are connected in the form of two switches belonging to two adjacent rings, In each ring composed of a plurality of switches including the two belonging switches, One of the two switches is located at the connection end of the ring, and is set as a master switch that closes one port during normal operation. In addition, the two switches belonging to the two belonging switches The switching priority for the ring is set,  In each ring, the master switch has a higher MEG level MEP in the Ethernet (registered trademark) OAM function, and a plurality of switches other than the master switch have a lower level in the Ethernet (registered trademark) OAM function. MEG level MEP and higher MEG level MIP are set,  In each ring, the master switch periodically transmits an Ethernet (registered trademark) OAM function CCM frame for confirming continuity from both ports so that it circulates around its own ring and faces the opposite ports. Instead of receiving the CCM frame, means for detecting whether or not to receive a VSM frame of the Ethernet (registered trademark) OAM function instructing one or both of the switching request and switching unnecessary, and the continuity check When the Ethernet (registered trademark) OAM frame received instead of the CCM frame is only the VSM frame indicating that switching is not required, the blocked state of the one port is maintained, while the VSM indicating the switching request is specified. When a frame is included, the blocked state of one of the ports is released and the MAC address learning table of the switch is flushed. And means for transmitting the VSM frame of Ethernet (registered trademark) OAM function of instructing the flash dress learning table,  For each ring, the two belonging switches are means for blocking the failed port when the CCM frame cannot be received, and the switch side to which the failed port belongs only to the ring. Means for transmitting the switching request instruction VSM frame instead of the CCM frame from the non-failure side port, and when the failure side port is the partner switch side belonging to two rings, the non-failure side port A means for transmitting the switching request instruction according to the switching priority for the ring instead of a CCM frame or a VSM frame for the switching not required instruction, and flushing of the MAC address learning table at the non-failure side port And a means for flushing the MAC address learning table of the switch when a VSM frame is received, Each switch, except the two belonging switches, has a master switch. Means for blocking the failed port when the CCM frame to be transmitted cannot be received, means for transmitting a VSM frame instructing a switching request from the non-failed port instead of the CCM frame, and the non-failed port Means for flushing the MAC address learning table of its own switch when a VSM frame instructing flushing of the MAC address learning table is received.  A ring network characterized by that. [5] In each ring, the master switch  When the blocking of the one port is released, if failure recovery can be confirmed by receiving the CCM frame for confirming the continuity from both ports, the one port is returned to the blocking state, and It has a means to transmit VSM frames of Ethernet (registered trademark) OAM function that instructs the release of blocking from both ports,  Each switch other than the master switch in each ring is  5. The apparatus according to claim 4, further comprising means for releasing the blockage when there is a port blocking the state of the port of the switch upon reception of the VSM frame instructing the release of the blockage. Ring network. [6] In each ring, the master switch  In the case where the blockage of the one port is released, if failure recovery can be confirmed by receiving the control frame for confirming the continuity from both ports, means for notifying the failure recovery to the outside, When a restoration switching instruction is input, the one port is returned to the closed state, and means for transmitting a VSM frame of the Ethernet (registered trademark) OAM function instructing the release of the blocking from both ports is provided.  Each switch other than the master switch in each ring is  5. The apparatus according to claim 4, further comprising means for releasing the blockage when there is a port blocking the state of the port of the switch upon reception of the VSM frame instructing the release of the blockage. Ring network.