JP5378239B2 - Information transmission system, information transmission method, and relay switch device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for achieving dual-homing redundancy switching in a packet network. <P>SOLUTION: In this information transmission system including an active-system path and a standby-system path composed by a packet network, an access switch for connecting both of them, and an active-system relay switch connected to an active-system service node, the active-system relay switch includes a state detection section 30 for monitoring a conduction state of a service provided by the active-system service node, a control section 32 for active-system redundancy for issuing an instruction of the change of a service node with respect to the active-system service node to the state detection section when defect is detected in the conduction state, and an OAM control section 54 for active-system redundancy for transmitting/receiving OAM to/from the access switch. The OAM control section 54 for redundancy stops transmission of the OAM when defect occurs in the conduction state, and the access switch switches the active-system path to the standby-system path being triggered by it. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to information transmission through a packet network, and more particularly to an information transmission system that performs dual homing redundancy switching.

  In recent years, telecommunications carriers are aiming to use NGN (Next Generation Network) based on packet networks with the aging of existing Synchronous Digital Hierarchy (SDH) facilities and the development of IP (Internet Protocol) services. It has become to. Standards for MPLS-TP (Multi Protocol Label Switching Transport Profile) and PBB-TE (Provider Backbone Bridge Traffic Engineering) as technologies for introducing the same path concept as SDH into a packet network (hereinafter referred to as “packet transmission technology”) The telecommunications carriers are using these packet transmission technologies to realize a large-capacity and high-throughput packet transmission service.

  In these packet transmission technologies, high-speed redundancy switching and enhancement of OAM (Operation Administration and Maintenance) have been attempted. However, switch devices used for packet transmission technologies are generally cheaper than SDH devices. Therefore, the reliability as a device tends to be low. For this reason, the transmission path tends to have redundancy (see Patent Document 1).

JP 2007-201575 A

  Conventional path protection is predicated on one-to-one path protection. In such a case, the path switching is a closed path having an access switching device (hereinafter referred to as an “access switch”) at both ends, and therefore, as in dual homing redundancy switching of a multi-site packet network. In addition, a one-to-two redundant path cannot be configured. It is possible to implement dual homing redundancy switching by implementing a protocol that is not standardized by the vendor in the access switch and the relay switch device (hereinafter referred to as “relay switch”). This unique protocol hinders interoperability between switches and can hinder multi-vendorization.

  In addition, in order to realize redundancy of the packet network, there is a method in which a relay switch routes and selects a detour route. Since this method requires complicated processing, software processing is generally applied, but high-speed redundancy switching cannot be realized by software processing. Furthermore, it is necessary to share the redundancy state between the relay switch devices, and a link between the relay switches is also required.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a system that realizes dual homing redundancy switching in a packet network.

  In order to solve the above-described problems, a system according to an aspect of the present invention includes an active path configured by a packet network, a standby path configured by a packet network, the active path, and the standby path. An active switch connected to the active service node, connected to an end different from the connection end of the access switch connected to both, and the access switch of the active path, and an access switch of the standby path And a backup relay switch connected to a backup service node and connected to a different end from the connection terminal. The active relay switch is connected to the active service node, and the active state detection is performed to monitor the continuity of the service set between the access switch and the active service node as a unit of monitoring. And an active redundancy control unit for notifying the active service state to the active service node when the active state detection unit detects a conduction state abnormality, An active redundant OAM control unit that is connected to the access switch via the active path and transmits / receives OAM to / from the access switch. The working redundancy OAM control unit receives notification of the conduction state abnormality from the working redundancy control unit, and stops transmission of the OAM to the access switch. When the OAM from the working redundant OAM control unit is stopped, the working path is switched to the backup path.

  When the OAM from the access switch is not transmitted for a predetermined period, the working redundancy OAM control unit notifies the working redundancy control unit that the OAM has been interrupted, and the working redundancy control unit When the active redundant OAM control unit receives a message that the OAM has been interrupted, the active state detection unit may notify the active service node of the change of the service node.

  The standby relay switch is connected to the standby service node, and a standby state detector that monitors a conduction state using a service set between the access switch and the standby service node as a unit of monitoring; The standby redundant OAM control unit that is connected to the access switch via the standby path and transmits / receives OAM to / from the access switch, and the standby state detection unit detects a conduction state abnormality. And a standby redundancy control unit that notifies the standby redundancy OAM control unit of the abnormality of the conduction state. The standby redundancy OAM control unit may stop the transmission of the OAM to the access switch upon receiving the abnormality in the conduction state from the standby redundancy control unit.

  The active relay switch may further include an active state detection control unit that changes a type of service that the active state detector detects as a unit of monitoring, and the standby relay switch includes the standby state The detection unit may further include a standby system state detection control unit that changes a type of service that is a unit of monitoring.

  According to this aspect, when an abnormality occurs in the conduction state between the active relay switch and the active service node, the OAM between the access switch and the active relay switch is interrupted. With this as an opportunity, the access switch can switch from the working path to the backup path. For this reason, dual homing redundancy switching can be realized. Here, the operation of the access switch may be the same as that in the conventional one-to-one path protection. Therefore, the devices constituting the access switch and the path may be devices that comply with the standardization method.

  Another aspect of the present invention is an information transmission method. The method includes: a first path configured by a packet network; a second path configured by a packet network; an access switch connected to both the first path and the second path; The first relay switch connected to the first service node and connected to the end different from the connection end to the access switch in the first path, and the connection end to the access switch in the second path In an information transmission system including a second relay switch connected to a different end and connected to a second service node, the first relay switch uses the first path and the access switch. Setting a service continuity state set with the first service node as a unit of monitoring, and based on the set unit Monitoring the service continuity with the first service node, and notifying the first service node of a service node change when an abnormality in the service continuity is detected. And the step of stopping the transmission of the OAM to the access switch when an abnormality in the continuity state of the service is detected. The access switch stops the OAM from the first relay switch. As a result, the first path is switched to the second path.

  According to this aspect, when an abnormality occurs in the conduction state between the first relay switch and the first service node, the OAM between the access switch and the first relay switch is interrupted. With this as an opportunity, the access switch can switch from the first path to the second path. For this reason, dual homing redundancy switching can be realized. Here, the operation of the access switch may be the same as that in the conventional one-to-one path protection. Therefore, the devices constituting the access switch and the path may be devices that comply with the standardization method.

  Yet another embodiment of the present invention is a relay switch device. The apparatus is connected to an access switch via a path formed by a packet network, is connected to a redundant OAM control unit that transmits / receives OAM to / from the access switch, a service node, and the access switch and the service A state detection unit that monitors the continuity state using a service set between the nodes as a unit of monitoring; and when the state detection unit detects an abnormality in the continuity state, the state detection unit A redundancy control unit that notifies the change of the service node, and the redundancy OAM control unit receives the notification of the abnormality of the conduction state from the redundancy control unit and transmits the OAM to the access switch. Stop.

  When the OAM from the access switch is not transmitted for a predetermined period, the redundancy OAM control unit notifies the redundancy control unit that the OAM has been interrupted, and the redundancy control unit transmits the OAM control unit When the fact that the OAM has been interrupted is received, the detection unit may be notified of the change of the service node to the service node.

  According to this aspect, when an abnormality occurs in the conduction state with the service node, transmission of OAM to the device connected to the opposite side of the service node with the relay switch device interposed therebetween may be stopped. it can. For this reason, it is possible to notify that an abnormality has occurred in the conduction state between the relay switch device and the service node.

  It should be noted that any combination of the above-described constituent elements and a representation obtained by converting the expression of the present invention between apparatuses, methods, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, it is possible to provide a system that realizes dual homing redundancy switching in a packet network without hindering multi-vendorization.

1 is a schematic configuration diagram of a packet network system according to an embodiment of the present invention. It is a figure which shows typically the internal structure of the relay switch which concerns on implementation of this invention. It is the flowchart which showed the flow until the monitoring unit of a redundant path is set to a state detection part, and a state detection part becomes a regular monitoring state. It is the flowchart which showed the flow until the recovery process when the state detection part 30 which shifted to steady monitoring detects steady monitoring and the above. It is the flowchart which showed the flow of state monitoring on the service node side. It is the flowchart which showed the flow of the state monitoring by the side of an access switch. It is the flowchart which showed the flow of the recovery process. It is a figure which shows a mode when a state abnormality generate | occur | produces in the service node side of an active system path | pass. It is a figure which shows a mode when a state abnormality generate | occur | produces in the access switch side of an active path. It is a figure which shows an example of the packet network which gave redundancy to the transmission path | route. It is a figure which shows an example of the dual homing redundancy switching of the packet network which made the service node multi-site.

  Prior to the description of the embodiment of the present invention, a presupposed technique will be described.

  FIG. 10 illustrates an example of a packet network in which a transmission path according to the underlying technology is made redundant. In the figure, the access switch AS1 (reference numeral 40) and the access switch AS2 (reference numeral 42) constitute a one-to-one path protection. Specifically, a path passing through the access switch AS1 (symbol 40) -relay switch IS1 (symbol 44) -packet network 52-relay switch IS3 (symbol 46) -access switch AS2 (symbol 42) is defined as a normal working path. If a failure occurs in the working path and an abnormality occurs in the transmission state, access switch AS1 (reference numeral 40) -relay switch IS3 (reference numeral 48) -packet network 52-relay switch IS4 (reference numeral 50) -Switch to a backup path that passes through the access switch AS2 (reference numeral 40), and secure a transmission path between the access switch AS1 and the access switch AS2. A feature of such a redundant configuration in the prior art is that access switches exist at both ends of the redundant path, and both ends of the path are closed.

  The packet transmission technology is assumed to be used not only between a customer and a customer, but also for use in connecting a customer and a service node. In addition, when telecommunication carriers procure access switches and relay switches, there are many cases where the vendors of the two are separated, and in order to ensure the interoperability between the access switch and the relay switch and between the relay switches. The standardization method tends to be preferred. On the other hand, in recent years, from the viewpoint of BC (Business Continuity), there are many forms in which service nodes are multi-sited.

  FIG. 11 illustrates an example of dual homing redundancy switching of a packet network in which service nodes according to the underlying technology are multi-sited. The access switch AS1 (reference numeral 40) is the same as that shown in FIG. 10, but a multi-site packet network differs from the packet network shown in FIG. 10 in that the access switch AS2 does not exist. In FIG. 11, the access switch AS1 (symbol 40) -relay switch IS1 (symbol 44) -the route through the packet network 52 to the service node SN1 (symbol 14a), access switch AS1 (symbol 40) -relay switch IS2 (symbol 48) −packet network 52−path to service node SN2 (symbol 14b) exists. Here, the service node SN1 (symbol 14a) and the service node SN2 (symbol 14b) are, for example, a primary server and a secondary server that provide services, respectively.

  In describing the embodiment, first, the outline thereof will be described. In the embodiment, the two relay switches connected to the two service nodes existing on the dual homing packet network are not directly linked to each other. These two relay switches not only exchange CC (Continuity Check) and other OAMs with the access switch at the branch point, but also monitor the conduction state with the service node. Even if the two relay switches are not directly linked to each other, the access switch can obtain information on the conduction state between the relay switch and the service node as long as the access switch is in conduction with the relay switch. For this reason, the access switch can realize one-to-two dual homing redundancy switching by the packet network only by performing the same operation as the conventional one-to-one path protection configuration.

  FIG. 1 is a schematic configuration diagram of a packet network system 100 according to an embodiment. The packet network system 100 shown in FIG. 1 is connected to the access path AS10 and the two relay switches IS12a and 12b, the active path 16a and the backup path 16b, and the relay switch IS12a by the packet network connecting the access switch AS10 and the relay switch IS12. Service node SN14a connected to relay switch IS12b and service node SN14b connected to relay switch IS12b. Hereinafter, dual homing redundancy switching in cooperation with the access switch AS10 and the relay switch IS12 will be described together with the internal structure of the relay switch IS12.

  FIG. 2 is a diagram schematically illustrating an internal configuration of the relay switch IS12 according to the embodiment. The relay switch IS12 includes a redundancy OAM control unit 54, a redundant path mapping unit 24, a main signal processing unit 26, a state detection control unit 28, a state detection unit 30, a redundancy control unit 32, and a switching flag 34. The redundancy OAM control unit 54 further includes a redundancy OAM detection / insertion unit 20 and a redundancy OAM generation / processing unit 22.

  The redundant path mapping unit 24 receives a redundant path monitoring unit from an external interface (not shown) and notifies the main signal processing unit 26 and the state detection control unit 28. Here, the “redundant path monitoring unit” refers to a path associated with some redundant service passed between the access switch AS10 and the service node SN14 using a packet network, IS12 is a unit for monitoring the conduction state. For example, a physical link of a packet network, a service flow such as CES (Circuit Emulation Service) provided by the service node SN 14, or a service flow in which traffic is constantly generated, or IEEE 802.1q / 802.1ad for multiple access, etc. A VLAN (Virtual Local Area Network) or the like is a redundant path monitoring unit.

  The redundant OAM detection / insertion unit 20 receives the redundant OAM from the access switch AS 10 via the path 16. The OAM is, for example, a service OAM for CC or VLAN, and the redundant OAM generating / processing unit 22 detects the redundant OAM at a predetermined interval according to the redundant path monitoring unit received from the redundant path mapping unit 24. It is checked whether or not the path 16 between the access switch AS10 and the relay switch IS12 is conductive by checking whether or not the insertion unit 20 has received OAM. The redundant OAM detection / insertion unit 20 transmits an OAM such as a CC to the access switch AS 10 via the path 16. In this way, if the path 16 between the access switch AS10 and the relay switch IS12 is conductive, the two can exchange OAM signals such as CC at a predetermined interval, so that the continuity can be confirmed. . When some state abnormality occurs in the path 16, both of them can detect LOC (Loss Of Continuity) as a state abnormality.

  The state detection control unit 28 sets the redundant path monitoring unit received from the redundant path mapping unit 24 in the state detection unit 30. When the status detection unit 30 succeeds in setting the redundant path monitoring unit, the status detection unit 30 notifies the status detection control unit 28 to that effect. The state detection control unit 28 notifies the redundant path mapping unit 24 that the redundant path monitoring unit received from the state detection unit 30 has been successfully set. Similarly, the redundant path mapping unit 24 notifies an external interface (not shown) that the setting of the redundant path monitoring unit is successful. The main signal processing unit 26 also notifies the redundant path mapping unit 24 when receiving the redundant path monitoring unit.

  Data such as a redundant OAM or packet transmitted from the access switch AS 10 via the path 16 is sent to the redundant OAM detection / insertion unit 20, the main signal processing unit 26, and the state detection unit 30 in the redundancy OAM control unit 54. Via the service node SN14. Data from the service node SN14 is sent to the access switch AS10 in the reverse order. Therefore, the state detection unit 30 monitors the presence or absence of a state abnormality such as whether or not the path is conductive according to the redundant path monitoring unit set by the state detection control unit 28. When a state abnormality is detected, the state detection unit 30 notifies the redundancy control unit 32 of the state abnormality. When the state detection unit 30 receives a control command for notifying the service node SN14 of the state abnormality from the redundancy control unit 32, the state detection unit 30 notifies the service node SN14 of the state abnormality.

  The redundancy control unit 32 notifies the redundancy OAM control unit 54 in accordance with the monitoring state of the state detection unit 30. For example, when the state detection unit 30 detects that the relay switch IS12 and the service node SN14 are not conductive, the redundancy OAM generation / processing unit 22 in the redundancy OAM control unit 54 is notified, and the redundancy The OAM generation / processing unit 22 controls the redundant OAM detection / insertion unit 20 to transmit an OAM indicating that the relay switch IS12 and the service node SN14 are not connected to the access switch AS10. The redundancy control unit 32 also receives a message from the redundancy OAM generation / processing unit when an abnormality occurs in the continuity with the access switch AS10, and the status detection unit 30 includes the access switch AS10 and the relay switch IS12. Control is performed so as to notify service node SN14 that it is not conducting.

  As described above, according to the relay switch IS12 of the embodiment, the redundant OAM detection / insertion unit 20 detects an abnormal state of the path between the access switch AS10 and the relay switch IS12, and the state detection unit 30 performs the relay. By detecting an abnormal state of the path between the switch IS12 and the service node SN14, it is possible to detect an abnormal state of the path in two directions across the relay switch IS12. For this reason, the access switch AS10 can obtain information on path state abnormalities in two directions across the relay switch IS12. Hereinafter, the access switch AS10 and the relay switch IS12 may be referred to as “access switch side”, and the relay switch IS12 and the service node SN14 may be referred to as “service node side”. Although details of the operation will be described later, the switching flag 34 is a binary flag that is on or off. When a path that is a redundant path monitoring unit has some continuity abnormality such as a continuity abnormality, the redundant OAM detection / insertion unit 20 or the state detection unit 30 switches from off to on, and the path has a state abnormality. Indicates that there is. When the abnormal state is resolved, either of them switches the switching flag 34 from off to on.

  FIG. 3 is a flowchart showing a flow from setting a redundant path monitoring unit to the state detection unit 30 until the state detection unit 30 enters a steady monitoring state. Here, the processing in this flowchart starts when the redundant path mapping unit 24 receives a redundant path monitoring unit from an external interface (not shown).

  The redundant path mapping unit 24 receives a redundant path monitoring unit from an external interface (not shown) (S10). The state detection control unit 28 sets the redundant path monitoring unit received from the redundant path mapping unit 24 in the state detection unit 30 (S12). When the monitoring unit of the set redundant path is VLAN (S14Y), the state detection unit 30 shifts to the VLAN Service OAM monitoring mode (S22). When the redundant path monitoring unit is not a VLAN (S14N), and when the redundant path monitoring unit is a service (S16Y), the state detection unit 30 shifts to a service flow monitoring mode (S18). When the redundant path monitoring unit is a physical link (S16N), the state detection unit 30 shifts to a physical link monitoring mode (S20). When the state detection unit 30 is set to one of the monitoring modes, the state is shifted to a steady monitoring state (S24). Hereinafter, when any one of the monitoring modes is set in the state detection unit 30 and is in a steady monitoring state, it is referred to as “steady state monitoring”.

  FIG. 4 is a flowchart showing the flow up to the recovery process when the state detection unit 30 that has shifted to the steady monitoring detects the steady monitoring and the abnormality. The processing in this flowchart starts when the state detection unit 30 shifts to regular monitoring.

  When the state detection unit 30 and the redundant OAM detection / insertion unit 20 shift to the regular monitoring, the two first check whether or not the switching flag 34 is ON indicating a path state abnormality. When the switching flag is ON (S26Y), the state detection unit 30 and the redundant OAM detection / insertion unit 20 shift to the recovery process (S32). When the switching flag is off (S26N), the state detection unit 30 monitors the state on the service node side (S28), and the redundant OAM detection / insertion unit 20 monitors the state on the access switch side (S30). ). When a state abnormality is detected on the service node side or the access switch side, the state detection unit 30 and the redundant OAM detection / insertion unit 20 shift to a recovery process (S32). When the restoration process is completed, the process returns to step S26 again, and regular monitoring is continued.

  FIG. 5 is a flowchart showing the flow of state monitoring on the service node side, and is a diagram illustrating step S28 in FIG. 4 in detail.

  The redundancy control unit 32 monitors whether or not the state detection unit 30 has detected a state abnormality (S34). While no state abnormality is detected by the state detection unit 30 (S36N), the operation of the state detection unit 30 is continuously monitored. When a state abnormality is detected by the state detection unit 30 (S36Y), the redundancy control unit 32 determines whether or not a state abnormality is detected in the redundancy OAM detection / insertion unit 20, and generates a redundant OAM. The inquiry is made by making an inquiry to the processing unit 22 (S38). When a state abnormality is detected in the redundant OAM detection / insertion unit 20 (S40Y), the redundancy control unit 32 checks whether or not the switching flag 34 is on. If the switching flag 34 is off ( (S42N), the switch flag is switched on (S44). In addition, when a state abnormality is not detected in the redundancy OAM detection / insertion unit 20 (S40N), the redundancy control unit 32 turns on the switching flag (S44). Thereafter, the redundancy control unit 32 instructs the redundancy OAM generation / processing unit 22 to execute the switching process, that is, the redundancy OAM detection / insertion unit 20 stops the CC (S46). When the switching flag 34 is on (S42Y) or when the switching process is executed, the process in this flowchart ends.

  As described above, when a state abnormality is detected on the service node side, by stopping the CC on the access switch side, the access switch AS10 can switch the active path 16a to the standby path 16b when CC stops. .

  FIG. 6 is a flowchart showing the flow of state monitoring on the access switch side, and is a diagram illustrating step S30 in FIG. 4 in detail.

  The redundancy OAM generation / processing unit 22 monitors whether or not the redundancy OAM detection / insertion unit 20 detects a state abnormality (S50). While no state abnormality is detected by the redundant OAM detection / insertion unit 20 (S52N), the operation of the redundant OAM detection / insertion unit 20 is continuously monitored. When a state abnormality is detected by the redundant OAM detection / insertion unit 20 (S52Y), the redundancy OAM generation / processing unit 22 determines whether the state detection unit 30 detects a state abnormality or not. The inquiry is made by inquiring to the section 32 (S54). When a state abnormality is detected in the state detection unit 30 (S56Y), the redundant OAM generation / processing unit 22 checks whether or not the switching flag 34 is on. If the switching flag 34 is off (S58N) ), The switch flag is switched on (S60). If no state abnormality is detected in the state detection unit 30 (S56N), the redundancy OAM generation / processing unit 22 turns on the switching flag (S60). Thereafter, the redundancy OAM generation / processing unit 22 instructs the redundancy control unit 32 to execute the service disconnection notification, that is, the state detection unit 30 instructs the service node SN14 to execute the service disconnection notification. (S62). When the switching flag 34 is on (S58Y) or when an instruction to execute a service interruption notification is given, the processing in this flowchart ends.

  As described above, when a state abnormality is detected on the access switch side, the service node SN14 can change the service route in response to the notification by notifying the service node SN14 of the service interruption.

  FIG. 7 is a flowchart showing the flow of the recovery process, and is a diagram illustrating step S32 in FIG. 4 in detail.

  The redundancy control unit 32 monitors whether a state abnormality is detected in the state detection unit 30, and the redundancy OAM generation / processing unit 22 determines whether a state abnormality is detected in the redundancy OAM detection / insertion unit 20. Is monitored (S64). While any state abnormality is detected (S66Y), the redundancy control unit 32 and the redundancy OAM generation / processing unit 22 continue to monitor the state abnormality. When no abnormal state is detected (S66N), the redundancy control unit 32 causes the state detection unit 30 to stop the service interruption notification process (S68). Further, the redundancy OAM generation / processing unit 22 causes the redundancy OAM detection / insertion unit 20 to stop the switching process (S70). Thereafter, the redundancy OAM generation / processing unit 22 or the redundancy control unit 32 sets the switching flag 34 to OFF (S72), and the processing in this flowchart ends.

  Returning to FIG. 1, a description will be given of the principle of realizing one-to-two dual homing redundancy switching in the packet network by the two relay switches IS12 and the access switch AS10.

  CC is periodically monitored between the access switch AS10 and the relay switch IS12a and between the access switch AS10 and the relay switch IS12b. That is, the access switch AS10 performs the same operation as the path protection with the conventional one-to-one redundant configuration. Each of the relay switch IS12a and the relay switch IS12b performs monitoring based on the redundant path monitoring unit set for the service node side. If there is no abnormality in the working path 16a and the path on the service node side of the working path 16a, the access switch AS10 and the service node SN 14a are connected via the working path. In the following, a description will be given of the flow until switching to the backup path when a status error occurs on the service node side or access switch side in the active path 16a.

  FIG. 8 is a diagram illustrating a situation where a state abnormality has occurred on the service node side of the active path 16a. The service node SN 14a and the service node SN 14b are, for example, a primary server and a secondary server that exist in the service network 18. Due to the occurrence of the state abnormality 36, the state detection unit 30 of the relay switch IS12a detects the state abnormality. When the redundancy OAM generation / processing unit 22 receives information on the state abnormality 36 from the redundancy control unit 32, the redundancy OAM generation / processing unit 22 instructs the redundancy OAM detection / insertion unit 20 to perform CC stop control. When the physical link between the switch IS12a and the service node SN14a is conductive, the redundancy control unit 32 notifies the service node SN14a of the change of the service route to the state detection unit 30. Instruct. When the redundant OAM detection / insertion unit 20 stops the CC, the access switch AS10 detects a LOC with the relay switch IS12a and switches to the backup path 16b. Thereby, it becomes possible to start transfer of the main signal between the access switch AS10 and the relay switch IS12b.

  In the conventional path protection with a one-to-one redundant configuration, the access switch AS10 existing at one switching end point detects a LOC with another access switch existing at the other switching end point. In the embodiment, the access switch AS10 switches to the backup path 16b triggered by the LOC detection with the relay switch IS12a. In the case of the access switch AS10, there is no influence on the operation regardless of the partner with whom OAM is exchanged. Therefore, according to the embodiment, the access switch AS10 can realize one-to-two dual homing redundancy switching only by performing the same operation as the conventional path protection with a one-to-one redundancy configuration.

  If the physical link between the switch IS12a and the service node SN14a is broken, the service node SN14a cannot receive the notification from the state detection unit 30, but in such a case, the relay switch is originally used. No information is transmitted from the IS 12a. Therefore, when no information is transmitted from the relay switch IS12a within a predetermined time, the service node SN 14a may change the service route.

  FIG. 9 is a diagram illustrating a situation when a state abnormality occurs on the access switch side of the active path 16a. Due to the occurrence of the state abnormality 38, the access switch AS10 and the relay switch IS12a each detect the LOC. When the access switch AS10 detects a LOC with the relay switch IS12a, the access switch AS10 switches to the backup path 16b. When the redundancy OAM detection / insertion unit 20 detects the LOC, the redundancy OAM generation / processing unit 22 of the relay switch IS12a notifies the redundancy control unit 32 of the fact. The redundancy control unit 32 instructs the state detection unit 30 to notify the service node SN 14a of the change of the service route. As described above, transfer of the main signal can be started between the access switch AS10 and the relay switch IS12b.

  According to the embodiment, since the procedure with the service node SN14 is performed by the relay switch IS12 alone, the access switch AS10 only needs to operate in the same manner as the conventional one-to-one path protection configuration. The apparatus can be used as it is. The same applies to the switch group constituting the path 16 connecting the access switch AS10 and the relay switch IS12. For this reason, the interconnectivity of the switch device can be maintained. Further, since it is not necessary to exchange information between the relay switch IS12a and the relay switch IS12b, a link between the two is also unnecessary. Since the relay switch IS12 does not need to perform processing such as routing and selecting a backup path that is a bypass route, high-speed redundancy switching is possible.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In the above-described embodiment, the case where a state abnormality occurs on either the access switch side or the service node side has been described, but switching is possible even when a state abnormality occurs on both sides simultaneously.

  10 access switch AS, 12 relay switch IS, 14 service node SN, 16 path, 18 service network, 20 redundant OAM detection / insertion unit, 22 redundant OAM generation / processing unit, 24 redundant path mapping unit, 26 main signal processing , 28 state detection control unit, 30 state detection unit, 32 redundancy control unit, 34 switching flag, 54 redundancy OAM control unit, 100 packet network system.

Claims (7)

A working path configured by a packet network;
A backup path configured by a packet network; and
An access switch connected to both the working path and the backup path;
An active relay switch connected to the active service node and connected to an end different from the connection end of the active path access switch;
A standby relay switch connected to a standby service node connected to an end different from the connection end of the backup path access switch;
The active relay switch and the standby relay switch are not directly linked to each other,
The active relay switch is
An active state detection control unit for setting a redundant path monitoring unit;
An active state detection unit that is connected to the active service node and monitors a conduction state using a service set by the active state detection control unit between the access switch and the active service node as a unit of monitoring. When,
When the active system state detection unit detects an abnormality in the conductive state, the active system state detection unit notifies the active service node of the change of the service node to the active system state detection unit; and
An active redundant OAM control unit that is connected to the access switch via the active path and transmits / receives OAM to / from the access switch;
The working redundancy OAM control unit receives notification of the conduction state abnormality from the working redundancy control unit, and stops transmission of the OAM to the access switch;
The access switch performs dual homing redundancy switching by switching the working path to the protection path when the OAM from the working redundancy OAM control unit is stopped. system. The active redundancy OAM control unit notifies the active redundancy control unit that the OAM has been interrupted when the OAM from the access switch is not transmitted for a predetermined period of time.
When the working redundancy control unit receives an OAM interruption from the working redundancy OAM control unit, the working redundancy detection unit causes the working state detection unit to notify the working service node of the change of the service node. The information transmission system according to claim 1. The standby relay switch is
A standby system state detection unit that is connected to the standby system service node and monitors a conduction state using a service set between the access switch and the standby system service node as a unit of monitoring;
A standby redundant OAM control unit that is connected to the access switch via the backup path and transmits / receives OAM to / from the access switch;
A standby redundancy control unit for notifying the standby redundancy OAM control unit of the conduction state abnormality when the standby system state detection unit detects a conduction state abnormality;
3. The standby redundant OAM control unit according to claim 1, wherein the standby redundant OAM control unit receives an abnormality in the conduction state from the standby redundant control unit and stops transmitting OAM to the access switch. Information transmission system. The active system state detection control unit changes the type of service that the active system state detection unit uses as a unit of monitoring,
The standby relay switch is
The information transmission system according to claim 3, further comprising a standby system state detection control unit that changes a type of service that is used as a monitoring unit by the standby system state detection unit. A first path constituted by a packet network;
A second path constituted by a packet network;
An access switch connected to both the first path and the second path;
A first relay switch connected to a first service node connected to an end different from the connection end to the access switch in the first path;
In an information transmission system including a second relay switch connected to an end different from the connection end with the access switch in the second path and connected to a second service node,
The first relay switch and the second relay switch are not directly linked to each other,
The first relay switch is
A step for setting a redundant path monitoring unit;
Setting a continuity of service set between the access switch and the first service node using the first path as a unit of monitoring;
Monitoring the continuity of the service with the first service node based on the set unit;
Notifying the first service node of a change in the service node when detecting an abnormality in the continuity state of the service;
Executing an OAM transmission to the access switch when detecting an abnormality in the service continuity state; and
The access switch performs dual homing redundancy switching by switching the first path to the second path when the OAM from the first relay switch is stopped. Method. A redundant OAM control unit that is connected to an access switch via a path formed by a packet network and transmits / receives an OAM to / from the access switch;
A state detection control unit for setting a redundant path monitoring unit;
A state detection unit that connects to a service node and monitors the continuity of the service set by the state detection control unit between the access switch and the service node as a unit of monitoring;
A redundancy control unit for notifying the state detection unit of a change of a service node in order to perform dual homing redundancy switching to the service node when the state detection unit detects a conduction state abnormality;
The relay switch device, wherein the redundancy OAM control unit receives notification of the abnormality of the conduction state from the redundancy control unit and stops transmission of the OAM to the access switch. When the OAM from the access switch is not transmitted for a predetermined period, the redundancy OAM control unit notifies the redundancy control unit that the OAM has been interrupted,
The said control part for redundancy makes the said detection part notify the change of a service node to the said service node, when the fact that OAM interrupted from the said OAM control part is received, The service node of Claim 6 characterized by the above-mentioned. Relay switch device.

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