JP4374268B2 - Cross-connect device, optical cross-connect device, and line relief method using the same - Google Patents

Description

  The present invention has a plurality of transmission lines, a device capable of editing a transmission line or a line that is multiplexed and accommodated in the transmission line, and a group of devices that relay and transmit signals flowing through the line are arranged in a mesh shape. The present invention relates to a network formed by interconnecting. In particular, a switching method for exchanging information between several relay devices when a failure occurring on the network is detected, and for relieving a line affected by the failure by editing the line; The present invention relates to a method for confirming the normality of a backup route of a line by exchanging information between several relay apparatuses in a state where no failure has occurred in the network.

  An optical cross connect (OXC) device using an optical switch that does not electrically convert an optical signal at the time of line editing is applied in place of a conventional switch for setting and editing a line using an electric signal. Studies and experiments have been conducted on methods for putting all optical networks into a mesh and interconnecting them.

  In addition, as a form of a network using a device conforming to SDH (Synchronous Digital Hierarchy) of ITU-T recommendation, as shown in FIG. 4, a linear configuration (FIG. 4 (a)) in which devices are arranged linearly, Or there exists a ring shape (FIG.4 (b)) arrange | positioned circularly. When a failure occurs in a network of these forms, a line switching method corresponding to each form is determined by ITU-T Recommendation G. 783 and G.R. 841 and the like are defined as MSP switching (Multiplex Section Protection).

  On the other hand, in a network in which the above-described optical cross-connect devices are arranged in a mesh shape, a line switching method such as the MSP switching has not been established. T Recommendation G. As shown in 783, “1 + 1 redundancy configuration” always having a protection line for one line, or “1: N redundancy configuration” having one protection line for n lines, etc. Is applied to realize high-speed line recovery in the event of a transmission line failure, and to cope with a device failure by, for example, duplicating the switch unit in the device.

  As an optical network line repair method, for example, there is an invention described in Patent Document 1 (such as that described in paragraphs [0061] to [0065]).

JP 2000-22630 A

  When the “1 + 1 redundant configuration” described above is applied to a mesh network, half of the communication bandwidth of the network is set as a protection line, so that it can be said to be a configuration that is highly reliable but less economical. In addition, although the economic efficiency is improved by applying the above-mentioned “1: N redundant configuration”, in both cases, when a failure occurs in a node, it is possible to quickly reset the line so as to avoid the node. There is a problem that it is not easy to execute. Furthermore, the optical switch applied to the optical cross-connect device is restored because the switching speed does not reach the electrical switch due to the structural difference when compared with the electrical switch applied to the SDH device so far. Speeding up is also an issue.

  In addition, ITU-T Recommendation G. In 709, various overhead information is defined in the OTN frame, and although information (bytes) for the purpose of line restoration is defined in the OTN frame, its usage is not defined. At present, it is necessary to establish a method for using this overhead information. Further, regarding the confirmation of the normality of the backup path, for example, if the normality confirmation is performed after detecting a transmission line failure, it takes more time to recover, so this needs to be solved.

  When a failure occurs on a network in which cross-connect devices are connected in a mesh, the method for relieving the affected line is to edit the line so that the trouble is avoided in the line that needs to be relieved. It can be solved by establishing a mesh network. For example, in the case of a failure in a certain transmission line, it is possible to relieve the line by editing the line so that all the lines passing through the transmission line are detoured to another transmission line. Further, in the case of a failure occurring in a certain node, all lines that pass through the node can be remedied by performing line editing that passes through other nodes.

  Specifically, in a mesh network, a node that detects a failure occurs on a detour route between a node that needs to edit the line affected by the failure and a node on the detour route of the line. It is possible to relieve by exchanging information on the line switching, editing all the corresponding lines, and switching to the detour route. In addition, in order to shorten the time required for this line relief, it is necessary to confirm the normality of the detour route (backup route) of the set line during normal operation (when no network failure has occurred). By regularly exchanging information between nodes and monitoring it, information on detour routes is collected and organized. As a result, it is possible to check the normality of the backup path, and if a failure occurs in the network where the normality of the backup path is confirmed in this way, the node that detected the fault will be affected by the fault. Send and receive information about switching the circuit to the detour route between the node that needs to edit the received circuit and the node on the circuit detour route, edit all the corresponding circuits, and switch to the detour route .

  According to the present invention, when a failure occurs in a network in which cross-connect devices are connected in a mesh shape, an affected line can be relieved at high speed by transferring information at high speed in the physical layer. Further, by using the protection path normality confirmation method of the present invention, it is possible to perform line rescue from a failure at higher speed without confirming the normality of the protection path after the occurrence of the failure.

  First, an outline of a configuration example of a network and an optical cross-connect device to which the present invention is applied will be described. FIG. 2 shows an example of a network configuration in the present invention. An optical signal input from the transmission line 230 is separated into a plurality of lines by a wavelength division multiplexing (WDM) apparatus 220, and the line is edited by an optical cross connect apparatus (OXC) 210, and edited. In this configuration, a plurality of lines are multiplexed by the wavelength division multiplexer 220 and input to the transmission path. Each optical cross-connect device 210 has a function of accommodating the transmission line 230 and the user line 240.

  FIG. 3 shows an example of the configuration of the optical cross-connect device 300 according to the present invention. As an interface of the device, a user interface unit (UNI) 340 and a network interface unit (NNI) 330 are provided. The user interface unit 340 is connected to a device having an optical interface such as an SDH transmission device, an ATM transmission device, or a high-speed IP router device. The network interface unit 330 is connected to a device for connecting nodes such as the normal wavelength multiplexing device 320. In these interface units, for example, G.I. It is assumed that signals can be transmitted and received according to the OTN frame defined in 709.

  The optical switch unit (OSW: Optical Switch) 310 has a function of changing the connection state of the lines from the user interface unit 340 and the network interface unit 330 (cross-connect function or the like). This function is used not only for setting a line in a network but also for relieving a line affected by a failure even when a failure occurs.

  In addition, the optical cross-connect device 300 includes a control unit 350 for controlling the above-described functions. The control unit 350 has at least a storage area such as a ROM and a RAM and a processor in the inside thereof, and is used for information exchanged between nodes at the time of line setting, recovery processing at the time of failure, normality confirmation of a backup path, etc. Processes and controls each node. The control unit 350 of each node is connected to a network management apparatus that manages and controls the entire network, and can exchange information about each node with the network management apparatus.

  A line rescue method according to the present invention using the above-described network configuration and optical cross-connect device, a backup path normality confirmation method, and a line rescue method using this backup path normality confirmation method will be described.

  First, the outline of the line repair method according to the present invention will be described with reference to FIG. FIG. 6A shows a mesh-type network. An optical cross-connect device arranged at a lattice point of the mesh is called a branch point node 610, and line editing is mainly performed at this branch point node. The configuration of this branch point node 610 is as shown as the optical cross-connect device 300 in FIG. Further, an optical cross-connect device or repeater arranged on a transmission line connecting the branch point nodes will be referred to as a relay node 620. In this network, as shown in FIG. 6A, a line 640 that passes through a plurality of branch point nodes 610-5, 610-6, 610-7, and 610-8 can be set.

  FIG. 6B shows a state where a failure 650 has occurred in the above-described line 640. In order to rescue this line, for example, a bypass route 660 for avoiding a failure is searched and determined. Then, switching control information is exchanged between the branch point nodes 610-6, 610-2, 610-3, and 610-7 on the detour route, and necessary lines are edited in each node, so that FIG. As shown in (c), the failure 650 can be bypassed to recover from the failure.

  Next, an example of the line repair method of the present invention will be described. FIG. 7A shows a management device 710 that performs monitoring control in the network of FIG. 6 and a network management network 720 to which signals from the control unit 350 of each node on the network are connected. The management apparatus 710 performs various initial settings for each branch point node 610 and then performs line settings for the entire network.

  FIG. 7B shows a state in which the management device 710 distributes in advance the information referred to by each branch point node 610 to the branch point nodes 610 before starting the line operation when switching the line. It is a thing. This distributed information is called a path table 740.

  FIG. 8 shows the contents of the path table 740. The path table 740 includes a failure in the branch point node 610 and branch point node information 810 regarding the state thereof, line information 820 regarding the line accommodated in the branch point node 610, and a line accommodated in the branch point node 610. Detour route information 830 regarding a detour route for detouring the line in the case of occurrence, interface information 840 regarding various interfaces of the branch point node 610, failure information 850 regarding occurrence of a failure in the node or interface portion, in the mesh network It is assumed that network information 860 relating to the position of the node is stored.

  The detour route information 830 is assumed to be set in association with a plurality of detour routes according to the type or location of the failure that has occurred, and the interface used when the detour route is determined is the same. Assume that they are associated. These path tables 740 have information unique to each node in a common format, and each piece of information is determined when the management apparatus 710 designs a line in the network.

  More specifically, in the path table 740, the line ID, line priority, line state information, information about the interface used by the line (wavelength, interface ID, switch state, etc.), line Information about other branch point nodes to which the node is connected (node ID, interface ID, etc.), information about the line affected by the failure, information about the normality of the detour route, information about the branch point node through which the detour route passes, Information that conveys a detour route, information about an optical interface unit used for line editing, information that indicates a switch state, and the like are also held.

  Next, an example of a line repair sequence is shown in FIG. FIG. 9A shows the location where the failure occurred, the circuit detour route, and the number of the branch point node 910 on the detour route. FIG. 9B shows the branch point nodes 910-2, 910-6, 910-7, and 910- on the detour route when the failure 900 that occurred in FIG. 9A is detected by the node B 910-3. 3 is a sequence diagram showing operations such as exchange control information exchange in FIG. Assuming that a line is set in the direction from the branch point node A 910-2 to the branch point node B 910-3, the operation of each branch point node 910 when a failure 900 occurs in the transmission path between them will be described.

  Examples of data in the path table 740 in the branch point node A 910-2, the branch point node B 910-3, the branch point node C 910-6, and the branch point node D 910-7 are shown in FIGS. 10 (a) and 10 (b), respectively. 11 (c) and 11 (d).

  First, the branch point node B 910-3 that has detected the failure 900 transfers an alarm toward the branch point node A 910-2 and the branch point node 910-4 downstream of the line (930-01). Thereafter, the branch point node B 910-3 refers to the path table described above, and selects, for example, one having a high priority from the circuit detour routes corresponding to the failure 900. At this time, in the path table 740 shown in FIG. 10B, as the information related to the detour route selected by the branch point node B 910-3, the information is arranged on the detour route 920, and the information is most similar to the branch point node B 910-3. A nearby branch point node D910-7 is defined as the switch request destination node ID (FIG. 10: 1030). With reference to this data, the branch point node B 910-3 issues a switching request 930-2 as switching control information to the branch point node D 910-7.

  When issuing a switching request, the switching request source interface ID (FIG. 10: 1031), which is the information associated with the selected detour route 920, is referred to for the transmission path interface, as in the previous case. Then, a signal obtained by mapping the switching request 930-2 to the OTN frame is transmitted.

  Next, the branch point node D 910-7 that has received the switching request 930-2 issued from the branch point node B 910-3 similarly refers to the path table 740, searches for the switching request transmission source node ID, and associates it with this. The switching request is transferred to the branch point node C910-6 indicated by the data stored in the switching request transfer destination node ID 1130.

  At the time of transfer, the switching control information is transferred after referring to the switching request transfer destination interface ID 1131 in the same manner as described above. Similarly, in accordance with the sequence shown in FIG. 9B, the branch point node 910 sequentially refers to its own path table 740 and inserts / transfers the switching control information. At that time, the connection state change (930-09, 930-11, 930-13, 930-18) in its own switch is also performed according to the switching control information.

  In this way, between the branch point nodes 910 that should be involved in line switching, the path table 740 owned by itself is referred to, and switching control information according to the switching state is inserted into the APS / PCC byte of the OTN layer or By transferring, the line where the fault finally occurred is relieved.

  Next, a method for detecting, generating, inserting, and transferring switching control information will be described. FIG. 1 is a block diagram relating to a control function of switching control information used at the time of line repair in the branch point node of the present invention. The switch unit 130 in FIG. 1 corresponds to the optical switch unit 310 in FIG. 3, and the input interface unit 110 and the output interface unit 140 in FIG. 1 are included in the network interface unit 330 in FIG. In the switching control information separation units 121 to 12N in the input interface unit 110, the switching control information in the ODUk overhead 510 defined in the frame 500 of the OTN layer of the signal input from the transmission path shown in FIG. The APS / PCC byte 511 to be used as a function is detected and input to the switching control information transfer unit 160.

  The switching control information transfer unit 160 monitors the switching control information input from the switching control information separation units 121 to 12N. When the input information indicates the occurrence of a failure on the network, the switching control information transfer unit 160 converts the switching control information into information necessary for switching or adds necessary information, and then outputs the output interface unit 140. The switching control information is output to the switching control information insertion unit to be transferred.

  Also in the operation of the switching control information transfer unit 160 at this time, information is detected, generated, inserted, and transferred with reference to the path table 740. The switching control information output from the switching control information transfer unit 160 is mapped to an OTN layer frame by the switching control information insertion units 151 to 15N of the output interface 140, and is output to the transmission path. FIG. 12 shows an example of the switching control information.

  The method described above is the ITU-T recommendation G.264. This is a case where switching control information is exchanged using the APS / PCC byte in the OTN frame in 709. In addition to the above, the present invention also includes ITU-T recommendation G.264. The present invention can also be applied to a cross-connect device using an SDH frame conforming to 707 and a network in which the cross-connect device is arranged in a mesh shape.

  The normality confirmation method of the backup route and the line repair method using the same will be described. An example of a block diagram of an apparatus to which this method is applied is shown in FIG. The difference from FIG. 1 is that FIG. 1 includes a block for processing a switching control signal used in the line repair method in each interface unit, whereas FIG. The difference is that each interface unit includes an OH information processing unit and an OH information demultiplexing unit that can also process normality confirmation information to be used.

  The branch node apparatus 1300 includes network node interface (NNI) units 1301 to 1304 that transmit main signals by optical signals or electrical signals, and user network interface (UNI) units 1305 and 1306 that store user signals. A switch unit 1307 with a light or electrical fabric corresponding to the main signal, which has a cross-connect function capable of selecting a route of the main signal (and overhead (OH) information incidental thereto), and each part in the node The monitoring control unit 1308 is configured to control and enable communication with the network management apparatus through the network management network.

  In each of the network node interface units 1301 to 1304, OH information multiplexing / separating units 1321 to 1324 having a function of multiplexing or separating overhead (OH) information to the main signal and the overhead (OH) information separated from each other are provided. OH information processing units 1311 to 1314 having processing functions are provided.

  The monitoring control unit 1308 includes at least a processor and a storage area such as a RAM and a ROM, and the storage area refers to and compares specific information (referred to as a node table) regarding data such as a node configuration and data. An information table (synonymous with the above-described path table, hereinafter referred to as a path table) that can determine the operation of the node by processing can be stored. The supervisory control unit 1308 includes a communication path 1309 other than the main signal transmission used for communication with the network management network. It is assumed that the node table and the path table can be updated with information acquired from outside / inside the apparatus.

  As shown in FIG. 6 and FIG. 7, the network to which the normality confirmation method of the backup path and the line repair method using the protection path described here are applied is a network node interface that the branch node device has. Assume that the network includes a network interconnected in a mesh form by 1301 to 1304, a network management device, and a network management network that enables communication between the branch point node device and the network management device.

  The normality check method of the backup path in the present invention checks the normality of the branch point node device and the transmission path (link) on the backup path with respect to the working line during normal operation of the network (no failure has occurred). In this method, the path table in the own node is updated according to the state.

  As described with reference to FIG. 6, a node device in which a plurality of output interfaces that can be selected for one input interface are mounted and usable is referred to as a “branch point node”. In contrast, a node device having only one selectable output interface for one input interface is referred to as a “relay point node”.

  In the working line (working path) set on the network, a route delimited by the branch point node on the working path is called a “partial path”. The partial path defined here has a branch point node at both ends, and includes a transmission path (link) between the nodes and a relay node existing on the transmission path. Further, it is assumed that the main path has a direction along the main signal flow, and the branch point node on the transmission side of the main signal is referred to as “starting node” and the branch point node on the receiving side is referred to as “end point node”.

  Next, the backup route will be described. As shown in FIG. 14, for the partial paths 1405 and 1406 of the working path 1404 set in the mesh network, when a failure occurs in a transmission path (link) and a relay point node on the path, A plurality of backup paths 1407 and 1408 (hereinafter referred to as backup paths) are calculated before operation, and some indexes (importance, transmission cost, transmission distance, bandwidth utilization ratio, etc.) are provided for each backup path. Priorities are assigned using. Similarly, a plurality of backup paths for relieving a line when a failure occurs at a branch point node located at both ends of a partial path is calculated before operation and given priority.

  For the calculated protection path, unique values (such as the ID of the corresponding partial path, the branch point node ID on the protection path, the ID of the network interface used at each branch point node, and the port ID of the switch) Or label). These associated information is recorded in the path table.

  As shown in FIG. 15, the network management apparatus 1501 distributes a path table 1503 corresponding to each node through the network management network 1502. Also, the distributed path table 1503 is stored in the storage area 1505 in the monitoring control unit 1308 in each node. Further, regarding the configuration contents of the path table 1503, a collection of information as shown in FIGS. 16 to 19 can be cited as an example.

  FIG. 16 shows an example in which the information in the path table is roughly classified and configured by line IDs 1601 and 1602, operation information 1603, priority order 1604, partial path information 1605, and the like. Here, the partial path information 1605 can be exemplified by information including partial path ID 1606, start node ID 1607, end node ID 1608, partial path input port 1609, partial path output port 1610, and the like.

  FIG. 17 shows a configuration example of backup path information 1611 that can be a component of the partial path information 1605. For this, a protection path ID 1701, a protection path priority 1702, a failure cause 1703 to be switched, which indicates the type of switching control information used to relieve a line when a failure occurs, that is, to switch from a partial path to a protection path, An example can be given of a backup path confirmation information type 1704 used when checking the normality of the backup path, other information 1705, and the like.

  FIG. 18 shows an example of the configuration of the failure factor 1703 to be switched and the information associated therewith which can be a component of the backup path information 1611. As an example of this, the protection path input port 1801 indicating to which switch port the protection path is input, information indicating the state of the port, information 1813 and 1814 regarding the connection source and the connection destination, For the protection path, information indicating the status of the protection path output port 1802 and its port that indicates which output port of the switch should be connected to the protection path input port 1801 of the previous period, information 1815 regarding the connection source and connection destination, etc. 1816 and a backup path adjacent node 1803 indicating information related to the node adjacent to the self node on the route of the backup path, and a backup path from the own node represented by a set of the node ID 1804 and the branch point node ID. Route information 1807 and its own node failure used for line rescue when a failure occurs in its own node Signals are output to the transfer destination node information 1808 of the switching control information at the time, the priority order 1809, the transfer destination node ID 1810, the input port 1811 of the switch receiving the signal from the transfer destination node, and the transfer destination node. An example of the configuration is information composed of information such as the output port 1812 of the switch.

  FIG. 19 shows a configuration example of information associated with the protection path normality confirmation information type 1704, which is a component of the protection path information 1611. The elements include information 1901 on the backup path adjacent node, the adjacent node ID 1902 which is detailed information thereof, the input port 1903 of the switch inputting the signal from the adjacent node, and the switch outputting the signal to the adjacent node. For example, an output port 1904 and information composed of information such as confirmation route information 1905 from its own node represented by a set of branch point node IDs can be given.

  FIG. 20 shows a configuration example of the node table. The node table can be exemplified by a table composed of information unique to each node regarding resources and the like. For example, detailed information of the network ID 2001, the sub network ID 2002, the node ID 2003, and the device information 2004, NNI-ID 2005 and UNI-ID 2006, switch ID 2007, switch port number 2008, input port ID 2009 and connection status information 2010, As an example, an output port ID 2011 and its connection state information 2012, a monitoring control unit ID 2013, other device information 2014, in-device failure information 2015, line failure information 2016, other information 2017, and the like can be given. .

  Next, an example of a method for confirming the normality of a transmission path (link) and a relay node in a backup path using a path table and information for normality confirmation (details will be described later) will be shown.

  As shown in FIG. 21, in one partial path 2101, either the branch point node I 2104 or the branch point node II 2105 (for example, transmission side: node I 2104) located at both ends of the partial path 2101 has a path table for the partial path 2101. For all of the backup paths defined therein, the normality is periodically confirmed periodically according to the priority order.

  For confirmation of the normality of the backup path, as shown in FIG. 21, for example, at the end point of the partial path 2101, the branch node I2104 located on the main signal transmission side sends information for normality confirmation, for example, Using the signal overhead information, the signal is transmitted to the branch point node II 2105 via all the node devices (branch point nodes and relay nodes) and the transmission path on the backup path. The node II 2105 having received the normality confirmation information finally transmits the normality confirmation information to the node I2104, so that the node I2104 monitors (diagnosis) the normality of the protection path based on the information returned to the node. Is to do.

  The normality confirmation information transfer path 2103 is mainly composed of the node II 2105 located on the side receiving the main signal, transfers the backup path in the direction toward the node I 2104, and finally transmits from the node I 2104 to the node II 2105. A route may be used.

  Next, normality confirmation information will be described. FIG. 22 shows an example of normality confirmation information. This is the ITU-T Recommendation G. 709 shows the case where ODUk (Optical Data Unit-k) overhead information 2201 in the OTN (Optical Transport Network) frame format defined in 709 is used. MFAS (MultiFrame Alignment 2) 202 bytes in this ODUk overhead 2201 And APS / PCC (Automatic Protection Switching coordination channel / Protection Communication Control Channel) byte 2203.

  FIG. 23 shows a usage example of the MFAS byte 2202 and the APS / PCC byte 2203. The MFAS byte 2202 is 1-byte information. 709 has a value incremented for each frame of OTN. In this method, the MFAS byte 2202 is interpreted in correspondence with the node ID information 2302 and 2303 at each node in the subnetwork, so that the backup path confirmation information issued or transferred by each node can be converted into a multiframe. (Independent channel).

  The APS / PCC byte 2203 is an ITU-T recommendation G.264. Reference numeral 709 denotes 4-byte information allocated for use in switching control or the like, but the usage method is not defined. In this method, the protection path normality confirmation information type 2305, information 2306 on the state of the node that issued or transferred the normality confirmation information, protection path ID 2307, subnetwork ID 2308, branch point on the protection path in these 4 bytes The node assigns information such as the node ID 2309 in the subnetwork in the node that issues the normality confirmation information, and the node ID 2310 in the subnetwork in the node that receives the normality confirmation information at the branch point node on the backup path.

  FIG. 24 shows an example of information values related to the type 2305 of the normality confirmation information assigned in the APS / PCC byte and the status 2306 of the node that issued or transferred the normality confirmation information when the normality of the protection path is confirmed. Show. As the type of normality confirmation information, values corresponding to normal state 2405 in which confirmation information is not issued / transferred, normality confirmation information 2404 and normality confirmation response 2403 indicating a response thereto, non-regulated information 2402, etc. Define. Regarding the information 2306 regarding the state of the node that transmitted the normality confirmation information, the values corresponding to the normal state 2410, the state 2409 that transmitted the normality confirmation information, the state 2408 that transmitted the normality confirmation response, the abnormality occurrence state 2407, etc. Define.

  Next, a method for confirming the normality of the backup path using the normality confirmation information described above will be described. FIG. 25 shows an example of a network in which nine branch point nodes (A to I) are interconnected in a mesh shape. The transfer path of normality confirmation information when a node located on the main signal transmission side at the branch point node of the partial path is the source of the normality confirmation information (here, node E2500) will be described.

  At the branch point node E2500, all the partial paths 2510, 2520, 2530, and 2540 that are the main signal transmission side in the working path accommodated by themselves are defined in the path table for each of them. Check the normality of all backup paths. For example, as shown in FIGS. 25A to 25D, the normality of the backup paths 2511 and 2512 is confirmed for the partial path 2510, and the normality of the backup paths 2521 and 2522 is confirmed for the partial path 2520. The normality of the backup paths 2531 and 2532 is confirmed for the path 2530, and the normality of the backup paths 2541 and 2542 is confirmed for the partial path 2540. Regarding the order of the partial paths for confirming the normality of the backup path, a method according to the priority order of the partial path information defined in the path table may be considered.

  Next, a transition of processing at each branch point node on the backup path when checking the normality of the backup path will be described with reference to FIG. In FIG. 26, among the partial paths of the branch point node E2601 that are directed to the node F (2600), the route is defined as the node E2601, the node B2602, the node C2603, and the node F2604. An example of a procedure for confirming a backup path is shown.

  As an example of a basic procedure, normality confirmation information 2605 is issued from the branch point node E2601, and transferred to all nodes on the backup path. The branch point node F 2604 that has received the normality confirmation information 2605 issues confirmation response information 2606 to the issuing branch point node E 2601. The branch point node E 2601 follows a path opposite to the normality confirmation information 2605. Transfer this until. The branch point node E 2601 that has received the confirmation response information 2606 transfers the confirmation response information 2606 to the node F 2604 using, for example, the partial path 2600 under investigation in order to notify the node F 2604 that it has been received.

  Each branch point node searches its own path table for each received normality confirmation information 2605 or confirmation response information 2606, and is associated with each information (normality confirmation information 2605 / confirmation response information 2606). The information transfer destination is determined based on the information (information related to the transfer destination adjacent node, etc.), and the transfer is performed. Here, regarding the issue / transfer timing of each information, the value of the MFAS byte described above is the APS / PCC byte of the frame that matches the node ID of the node E2601, which is the branch point node of the normality confirmation information 2605. On the other hand, a value corresponding to each information is inserted.

  Further, when a failure in the own node or a transmission path failure is detected in each node, the abnormal state is transferred (the node that transmitted (b) normality confirmation information in the APS / PCC byte shown in FIG. 24) For the information 2406 relating to the status of the network, a value indicating the abnormal status 2407 is inserted), and a failure recovery operation is performed using a line remedy method to be described later if necessary.

  Examples of the transfer path and the confirmation procedure of the normality confirmation information and the confirmation response information include those shown in FIGS. 27 and 28.

  Next, taking the backup path confirmation procedure shown in FIG. 26 as an example, details of the operation for each node will be described. FIG. 29 shows an example of association relating to items in the path table 2900 for determining the operation of the node. Here, an example in which the path table 2900 is mainly composed of three elements (working path information, partial path information, and backup path information) is given. Assuming that the working path information # 1 (2910) set in the network is composed of partial path #information 1 (2911) to #m (2913), a spare is assigned a priority to each of the partial paths. Associate path information 2914-2919. This can be generated for all the working paths in the network and used as the path table 2900 for the entire network. On the other hand, for each branch point node, a path table configured based on information associated with a partial path accommodated by the own node may be distributed.

  FIG. 30 shows an example of the contents of the path table of the node E2601 and the order of referring to it. In this example, the elements of the path table 2900 are configured with more detailed information, and the operation of the node is determined with reference to these values. The numbers enclosed in a circle in the figure indicate the correspondence with the numbers in the normality confirmation procedure in FIG. FIG. 31 shows an example of the correspondence between the interface ID or switch port ID represented by the value in the path table and each part of the node E2601. For each part of the node E2601, examples of values or labels given to the input interface IDs 3111 to 3115 and the output interface IDs 3121 to 3125, the input port IDs 3131 to 3135 of the switch, the output port IDs 3141 to 3145, and the like can be given.

  FIG. 32 shows an example of a backup path normality confirmation procedure in the node E2601. First, in order to select the highest priority among the backup paths for the partial path to be investigated, the priority value is determined (3201). Next, the path table in the node E2601 is referred to, and the “reserved path equal to the priority order” is searched from the partial path information of the originating node as the origin node among the partial paths in the operating state (3202). Thereafter, an information group in which “APS / PCC type” is “normality confirmation information (CfM)” is searched from information associated with the corresponding partial path (3203). Next, “adjacent node SW input compatible IF” and “adjacent node SW output compatible IF” are searched from the protection path information associated with the corresponding “APS / PCC type (CfM)” (3204). Thereafter, for the OH information processing unit (such as 1301 in FIG. 13) in the corresponding “adjacent node SW output correspondence IF”, the normality confirmation information (CfM + CfMT +... .) Is inserted into the APS / PCC byte (3205). When the information indicating the confirmation response information is detected in the OTN frame in which the MFAS byte matches the own node ID in the corresponding “adjacent node SW input compatible IF”, the information is transmitted from the “adjacent node SW output compatible IF”. The normality confirmation information value is changed to a normal state value (NR + IDLE +...), And among the information associated with the partial path under investigation, the “APS / PCC type” is “confirmation response information (CfR)”. Is searched for (3206).

  Thereafter, “adjacent node SW input compatible IF” and “adjacent node SW output compatible IF” are searched from the backup path information associated with the corresponding “APS / PCC type (CfR)” (3207).

  Thereafter, for the OH information processing unit (such as 1301 in FIG. 13) in the corresponding “adjacent node SW output corresponding IF”, confirmation response information (CfR + CfRT +...) Is added to the OTN frame in which the MFAS byte and the own node ID match. ) Is inserted into the APS / PCC byte (3208), and in the corresponding “adjacent node SW input corresponding IF”, from the node B that has been inserted into the OTN frame in which the MFAS byte and its own node ID match. When it is detected that the confirmation response information has been changed to the normal state value (NR + IDLE +...), The confirmation response information value transmitted from the “neighboring node SW output correspondence IF” is changed to the normal state value (NR + IDLE +. (3209). This completes the normality check of the backup path under investigation.

  After that, when the normality confirmation for all the backup paths defined in the path table for the partial path under investigation has been completed, the partial path ID = next partial path ID, the priority order of the backup path = 01. If not, the priority of the protection path under investigation = the next priority (3210) and the normality check of the protection path is continued. Here, if a problem occurs during each procedure, error processing (3200) is executed.

  FIG. 33 shows an example of the flow of normality confirmation information and confirmation response information exchanged between nodes. The numbers enclosed in a circle in the figure indicate the correspondence with the normality confirmation procedure numbers at node E shown in FIG.

  Next, the operation of the nodes B and C during the backup path normality confirmation procedure in the node E will be described. FIG. 34 shows an example of the contents of the node B path table and the order of referring to the contents. FIG. 35 shows an example of the correspondence between the interface IDs and switch port IDs represented by the values in the path table and each part of the node B.

  FIG. 36 shows an example of the normality confirmation procedure of the backup path in the node B. First, when normality confirmation information (CfM) is received at the interface unit, “APS / PCC type” is “normality confirmation information” in the information group matching the protection path ID inserted in the APS / PCC byte. (CfM) ”is searched in the path table (3601). Further, since the end node ID of the APS / PCC byte detected at this time does not match the own node ID, the subsequent operation is performed. Of the backup path information associated with the corresponding “APS / PCC type (CfM)”, “adjacent node SW input corresponding IF” and “adjacent node SW output compatible IF” are searched (3602).

  Thereafter, normality confirmation information (CfM + CfMT +...) Is sent to the OH information processing unit in the corresponding “adjacent node SW output correspondence IF” in the OTN frame that matches the first detected MFAS byte, and the APS / PCC byte. Is inserted (3603). Thereafter, in the corresponding “adjacent node SW input compatible IF”, when information indicating the acknowledgment information is detected in the OTN frame that matches the first detected MFAS byte, the information is transmitted from the “adjacent node SW output compatible IF”. The value of the normality confirmation information that has been changed to the normal state value (NR + IDLE +...), And among the information associated with the backup path under investigation, the “APS / PCC type” is “confirmation response information (CfR)”. "Is searched (3604).

  Thereafter, “adjacent node SW input corresponding IF” and “adjacent node SW output corresponding IF” are searched from the protection path information associated with the corresponding “APS / PCC type (CfR)” (3605). After that, the acknowledgment information (CfR + CfRT +...) Is sent to the APS / PCC byte in the OTN frame that matches the first detected MFAS byte for the OH information processing unit in the corresponding “adjacent node SW output correspondence IF”. An instruction to insert is given (3606).

  After that, in the corresponding “adjacent node SW input correspondence IF”, the confirmation response information from the node E inserted in the OTN frame that matches the first detected MFAS byte is changed to the normal state value (NR + IDLE +...). Confirmation response from the node C inserted in the OTN frame that coincides with the first detected MFAS byte in the “adjacent node SW input corresponding IF” corresponding to the search when the CfM is received. When it is detected that the information has been changed to the normal state value (NR + IDLE +...), The value of the acknowledgment information transmitted from the corresponding “adjacent node SW output corresponding IF” is changed to the normal state value (NR + IDLE +. (3607). This completes the backup path confirmation operation at the node B. Further, if a problem occurs during each procedure, error processing (3600) is executed.

  FIG. 37 shows an example of the flow of normality confirmation information and confirmation response information exchanged between nodes. The numbers enclosed in a circle in the figure indicate the correspondence with the normality confirmation procedure numbers at the node B shown in FIG.

  As for the node C, first, when the normality confirmation information (CfM) is received in the interface unit, the “APS / PCC type” of the information group matching the protection path ID inserted in the APS / PCC byte is set. Search the path table for “normality confirmation information (CfM)”. Since the end node ID of the APS / PCC byte detected at this time does not match the own node ID, the subsequent operation of the node C performs the same operation as that of the node B.

  Next, the operation of the node F when the node E is checking the normality of the protection path will be described. FIG. 38 shows an example of the contents of the path table of the node F and the order of referring to the contents. FIG. 39 shows an example of the correspondence between the interface IDs and switch port IDs represented by the values in the path table and the node F.

  FIG. 40 shows an example of a backup path normality confirmation procedure in the node F. First, when normality confirmation information (CfM) is received at the interface unit, “APS / PCC type” is “normality confirmation information” in the information group matching the protection path ID inserted in the APS / PCC byte. (CfM) "is searched in the path table (4001). Further, since the end node ID of the APS / PCC byte detected at this time matches the own node ID, the subsequent operation is performed.

  Of the backup path information associated with the corresponding “APS / PCC type (CfM)”, “adjacent node SW input corresponding IF” and “adjacent node SW output compatible IF” are searched (4002). After that, the acknowledgment information (CfR + CfRT +...) Is sent to the APS / PCC byte in the OTN frame that matches the first detected MFAS byte for the OH information processing unit in the corresponding “adjacent node SW output correspondence IF”. An instruction to insert is issued (4003). After that, in the corresponding “adjacent node SW input correspondence IF”, the confirmation response information from the node C inserted in the OTN frame that matches the first detected MFAS byte is changed to the normal state value (NR + IDLE +...). If it is detected, the information group whose “APS / PCC type” is “confirmation response information (CfR)” is searched from the information associated with the backup path under investigation (4004).

  Thereafter, “adjacent node SW input corresponding IF” and “adjacent node SW output corresponding IF” are searched from the protection path information associated with the corresponding “APS / PCC type (CfR)” (4005). After that, in the corresponding “adjacent node SW input corresponding IF”, when the confirmation response information from the node E inserted in the OTN frame that coincides with the first detected MFAS byte is detected, at the time of searching when the CfM is received The value of the confirmation response information transmitted from the corresponding “adjacent node SW output correspondence IF” is changed to a normal state value (NR + IDLE +...) (4006). After that, in the corresponding “adjacent node SW input correspondence IF”, the confirmation response information from the node E inserted in the OTN frame that matches the first detected MFAS byte is changed to the normal state value (NR + IDLE +...). If it is detected, the operation for the backup path under investigation is completed (4007). Further, if a problem occurs during each procedure, error processing (4000) is executed.

  FIG. 41 shows an example of the flow of normality confirmation information and confirmation response information exchanged between nodes. The numbers enclosed in a circle in the figure indicate the correspondence with the normality confirmation procedure numbers at the node F shown in FIG.

  As described above, it is possible to confirm the normality of the backup path with respect to the partial path of the origin node. Further, the use of the MFAS byte enables each node to confirm the normality of the backup path independently and asynchronously.

  Next, a line repair method using the above-described protection path normality confirmation method will be described. This method applies to the devices and networks described so far, and assumes that each node autonomously checks the normality of the backup path using the backup path normality check method described above. . This makes it possible to realize high-speed failure recovery in the mesh network while sharing the backup route.

  As shown in FIG. 42, this method is a line remedy method applied when a failure occurs in a transmission path (or the above-described relay node) and a branch point node of a mesh network. As shown in FIG. 42, transmission path failure factors include transmission path disconnection (4201), signal degradation (4202), and the like. As for the failure of the branch point node, there are a switch failure (4203), an interface unit failure (4204), a monitoring control unit failure (4205), a power failure (4206), and the like.

  FIG. 43 shows a procedure example of line rescue (failure recovery) for a transmission line failure. In the line rescue method using the protection path normality confirmation method described below, when the branch point node F4304 on the main signal reception side detects the transmission line failure 4307, the failure recovery action is started. An example of the sequence is shown in the lower part of FIG. As an outline, the node F4304 refers to the path table in the own node after detecting the failure, and since the own node is the end node of the partial path, The switch connection state is changed for the backup path with higher priority, and this is sent to the node C4303 to notify the node C4303 adjacent to the node F4304 at the branch point node on the backup path. Notification is made by inserting switching control information (“switching request”) in the APS / PCC byte included in the overhead (OH) information of the signal.

  Receiving this, the node C 4303 refers to the path table, and since the own node is neither the starting node nor the ending node of the partial path, if there is no abnormality in the backup path, after connecting the backup path, the node F 4304 In the same manner as described above, the branch point node on the protection path includes the overhead (OH) information of the signal transmitted to the node B 4302 to notify the adjacent node (here, the node B 4302) to which the switching control information is to be transmitted. Notification is made by inserting switching control information ("switching request") in the APS / PCC byte to be received.

  The node B 4302 receives the switching control information from the node C 4303 and then refers to the path table, and performs the same operation as the node C 4303 because the own node is neither the starting node nor the ending node of the partial path. In other words, if there is no abnormality in the protection path, after connecting the protection path, similar to the nodes F4304 and C4303, the branch node on the protection path is the adjacent node to which the switching control information should be transmitted (here Then, in order to notify the node E4301, the notification is made by inserting the switching control information ("switching request") into the APS / PCC byte included in the overhead (OH) information of the signal transmitted to the node E4301.

  In the node E4301, after receiving the switching control information from the node B4302, the path table is referred to, and since the self node is the starting node of the partial path, the connection state of the switch is changed when there is no abnormality in the backup path. . At this point, switching to the backup path is completed. Thereafter, the node E4301 notifies each branch point node on the backup path of the completion of the switching, so that the overhead (OH) of the signal sent to the adjacent node (here, the node B4302) to which the switching control information is to be transmitted. Notification is made by inserting switching control information ("switching complete") into the APS / PCC byte included in the information. Thereafter, each branch point node on the switched backup path transfers the switching control information (“switching complete”) to reach the branch point node F4304 which is the end point node of the partial path where the failure has occurred.

  As described above, each branch point node performs switch connection change and switch control information transmission in a chained manner, thereby realizing high-speed failure recovery in a mesh network.

  FIG. 44 shows a usage example of the MFAS byte 4401 and the APS / PCC byte 4404 at the time of failure recovery. The usage of the MFAS byte 4401 in this failure recovery method is interpreted in correspondence with the respective node IDs (4402, 4403) at each node in the sub-network, as in the normality confirmation method of the backup path. The switching control information issued or transferred by each node is used to make a multiframe (independent channel).

  As for the usage of the APS / PCC byte 4404 in this failure recovery method, the state of the node that issued or transferred the switching control information type 4405 and the switching control information to these 4 bytes as in the normality confirmation method of the protection path. Information 4406, protection path ID 4407, sub-network ID 4408, information on node ID 4409 in the sub-network, node ID 4410 in the sub-network of the end-point node of the starting node of the partial path to be switched (failed), etc. Assign.

  FIG. 45 shows an example of the switching control information type 4501 assigned in the APS / PCC byte and information 4507 related to the state of the node that issued or transferred the switching control information at the time of failure recovery. The switching control information type 4501 includes a normal state 4506 in which the switching control information is not issued / transferred, various factors of the switching request (intra-node switch failure 4503, signal disconnection 4504, signal degradation 4505, etc.), non-regulated information 4502, etc. Define a value corresponding to. For the information 4507 related to the state of the node that transmitted the switching control information, values corresponding to the normal state 4510, the switch connection changed (switching completed) state 4509, the abnormal state 4508, and the like are defined.

  FIG. 46 shows an example of the contents of the path table for failure recovery in the node F and the order of referring to the contents. The numbers enclosed in a circle in the figure indicate the correspondence with the numbers in the failure recovery procedure example in FIG. FIG. 47 shows an example of the correspondence between the interface ID and switch port ID represented by the values in the path table and each part of the node F, and a change example of the connection state.

  FIG. 48 shows an example of the failure recovery procedure in the node F. First, in the node E, when the transmission path failure (SF) is detected (4801) in the interface unit (IFi-02) that accommodates the partial path E → F, the operational status is detected from the path table in the own node. Among the partial paths of the path, “part having the highest backup path priority (01)” is searched for among the partial path information of which the own node is the origin node (4802). After that, among the information associated with the corresponding protection path (priority = 01), an information group with “APS / PCC type” of “transmission path failure (SF)” is searched (4803), and the corresponding “APS / PCS / Among the backup path information associated with “PCC type (SF)”, “adjacent node SW input compatible IF” and “adjacent node SW output compatible IF” are searched (4804). After that, a switching request (SF +...) Is inserted into the APS / PCC byte in the OTN frame in which the MFAS byte and its own node ID match for the OH information processing unit in the corresponding “adjacent node SW output compatible IF”. (4805).

  After that, in order to switch to the backup path, the “backup path SW input port ID” and “backup path SW output port ID” are obtained from the corresponding backup path information when the backup path is searched by “APS / PCC type”. A search (4806) is performed, and the connection state of the signal in the failed partial path E → F is changed to the corresponding information (4807). After that, when information indicating the completion of switching is detected in the OTN frame in which the MFAS byte and the own node ID match in the “adjacent node SW input compatible IF”, the switching transmitted from the “adjacent node SW output compatible IF” The request (SF +...) Value is changed to the normal state value (NR + IDLE...) (4808), and then the node table and path table information is updated (4809). Further, if a problem occurs during each procedure, error processing (4800) is executed.

  FIG. 49 shows an example of a failure recovery path table in node C and the order of reference when failure recovery starts in node F. The numbers enclosed in a circle in the figure indicate the correspondence with the numbers in the failure recovery procedure example in FIG. FIG. 50 shows an example of the correspondence between the interface ID and the switch port ID represented by the values in the path table, and the signal connection state before and after the failure recovery.

  FIG. 51 shows an example of the failure recovery procedure in the node C. First, in the node C, the switching request (SF +...) Is detected by the interface unit (IFi-02) (5101). Since the own node ID does not match the starting node ID and the ending node ID in the switching control information, the subsequent processing is executed.

  The path table is searched for a partial path of the active path that matches the detected start and end nodes, and the detected switch request is being detected from the backup paths of the corresponding partial path. A backup path that matches the backup path ID is searched (step 5102). After that, the information group of the switching factor (SF) of the APS / PCC byte whose “APS / PCC type” is requested to be switched is searched from the information associated with the corresponding protection path (5103). Thereafter, “adjacent node SW input corresponding IF” and “adjacent node SW output corresponding IF” are searched from the backup path information associated with the corresponding “APS / PCC type (SF)” (5104). Thereafter, for the OH information processing unit in the corresponding “adjacent node SW output corresponding IF”, a switching request (SF +...) Is transferred to the MFAS byte OTN frame that matches the MFAS byte when the switching request is detected. / PCC byte is inserted, and the switching request is transferred (5105).

  Thereafter, in order to switch to the backup path, search for “backup path SW input port ID” and “backup path SW output port ID” from the backup path information associated with “APS / PCC type (SF)” ( 5106) and connect the respective ports (5107). Thereafter, in the “adjacent node SW input compatible IF”, when information indicating the completion of switching is detected in the OTN frame of the MFAS byte that matches the MFAS byte when the switching request is detected, the “adjacent node SW output compatible IF” Change the value of the switching request (SF +...) Transmitted from (1) to the normal state value (NR + IDLE +...) (5108), and then update the node table and path table information (5109). Further, if a problem occurs during each procedure, error processing (5100) is executed.

  FIG. 52 shows an example of a failure recovery path table in the node B and the order of reference when the failure recovery is started in the node F. The numbers enclosed in a circle in the figure indicate the correspondence with the numbers in the failure recovery procedure example in FIG. FIG. 53 shows an example of correspondence between the interface ID and the switch port ID represented by the values in the path table, and the signal connection state before and after the failure recovery.

  FIG. 54 shows an example of a failure recovery procedure in the node B. First, in the node B, a switching request (SF +...) Is detected by the interface unit (IFi-02) (5401). Since the own node ID does not match the starting node ID and the ending node ID in the switching control information, the subsequent processing is executed. The path table is searched for a partial path of the active path that matches the detected start and end nodes, and the detected switch request is being detected from the backup paths of the corresponding partial path. A backup path that matches the backup path ID is searched (5402).

  Thereafter, the information group of the switching factor (SF) of the APS / PCC byte whose “APS / PCC type” is requested to be switched is searched from the information associated with the corresponding protection path (5403). Thereafter, “adjacent node SW input compatible IF” and “adjacent node SW output compatible IF” are searched from the backup path information associated with the corresponding “APS / PCC type (SF)” (5404). Thereafter, for the OH information processing unit in the corresponding “adjacent node SW output corresponding IF”, a switching request (SF +...) Is transferred to the MFAS byte OTN frame that matches the MFAS byte when the switching request is detected. / PCC byte is inserted, and the switching request is transferred (5405). Thereafter, in order to switch to the backup path, search for “backup path SW input port ID” and “backup path SW output port ID” from the backup path information associated with “APS / PCC type (SF)” ( 5406) to connect the respective ports (5407). Thereafter, in the “adjacent node SW input compatible IF”, when information indicating the completion of switching is detected in the OTN frame of the MFAS byte that matches the MFAS byte when the switching request is detected, the “adjacent node SW output compatible IF” Change the value of the switching request (SF +...) Transmitted from (5408) to the normal state value (NR + IDLE +...), And then update the node table and path table information (5409). Further, if a problem occurs during each procedure, error processing (5400) is executed.

  FIG. 55 shows an example of a failure recovery path table in the node E and the order of referring to this when the node F enters the failure recovery. The numbers enclosed in a circle in the figure indicate the correspondence with the numbers in the failure recovery procedure example in FIG. FIG. 56 shows an example of the correspondence between the interface ID and the switch port ID represented by the values in the path table, and the signal connection state before and after the failure recovery.

  FIG. 57 shows an example of a failure recovery procedure in the node E. First, in the node E, the switching request (SF +...) Is detected by the interface unit (IFi-01) (5701). Since the own node ID matches the starting node ID in the switching control information, the subsequent processing is executed. The path table is searched for a partial path of the active path that matches the detected start and end nodes, and the detected switch request is being detected from the backup paths of the corresponding partial path. A backup path that matches the backup path ID is searched (5702). After that, the information group of the switching factor (SF) of the APS / PCC byte whose “APS / PCC type” is requested to be switched is searched from the information associated with the corresponding protection path (5703).

  Thereafter, in order to switch to the backup path, search for “backup path SW input port ID” and “backup path SW output port ID” from the backup path information associated with “APS / PCC type (SF)” ( 5704) and the respective ports are connected (5705). At this point, the main signal flow is that the connection to the backup path that bypasses the failure that occurred in the partial path E → F has been completed. Thereafter, “adjacent node SW input corresponding IF” and “adjacent node SW output corresponding IF” are searched from the backup path information associated with the corresponding “APS / PCC type (SF)” (5706). After that, for the OH information processing unit in the corresponding “adjacent node SW output corresponding IF”, switching completion (NR + Switched +...) Is indicated in the MFAS byte OTN frame that matches the MFAS byte when the switching request is detected. An instruction to insert information into the APS / PCC byte is issued (5707), and the information in the node table and path table is updated (5708). Further, if a problem occurs during each procedure, error processing (5400) is executed.

  Next, an example of a failure recovery procedure for a node failure will be described. FIG. 58 shows a partial path (hereinafter referred to as partial path E → F5808) from the branch point node E5805 to the branch point node F5806 when a switch failure 5809 such as inability to connect a route occurs at the branch point node E5805. ) Is a terminal node F5806 which is an end point node, and an example in which a spillover fault having the same fault type as a transmission path fault is detected, and a fault recovery procedure example. Here, it is assumed that the partial path E → F5808 and the partial path D → E5807 are partial paths in the same path 5810 (the main signal flows as D → E → F).

  Since each of the nodes E5805 and F5806 detects a failure, each enters a failure recovery operation. However, since a conflict occurs when the switch connection state is changed in the node B5802, the partial path E → The priority of recovery from a node failure in the partial path D → E5807 may be set high with respect to the spillover failure in F5808 (having a priority similar to the transmission path failure). Specifically, the node B 5802 performs switch connection setting and switching control information processing according to this priority order.

  Next, each failure recovery operation will be described. First, since a failure such as inability to connect to a route has occurred in the switch at the node E5805, if this is detected, the partial path set in the own node is detected. It is necessary to change the route so that it does not go through its own node. However, in the case of a failure such as inability to connect the route, a spillover failure occurs on the receiving side of the main signal accompanying this, so node E5805 Then, the transmission / reception of the switching signal is performed in the same manner as the restoration of the failure at the time of detecting the transmission line failure, and the node F5806 side that receives the main signal from the node E5805 also detects the transmission line failure. By performing failure recovery similar to the time, a unified operation of “starting failure recovery mainly by the reception side of the main signal” becomes possible.

  Specifically, the protection path at the time of node failure detection in the partial path D → E5807 is set as D → A → B → E, and the protection path at the time of detection of the spillover failure in the partial path E → F5808 is E → The node B5802 is set to B → C → F, and the failure recovery operates so as to switch to each backup path, and the failure recovery priority in the partial path D → E5807 is high. The switch connection setting corresponding to the recovery from the node failure in the partial path D → E5807 may be performed (in this case, the main signal from the node A 5801 is set toward the node C 5803). These operations can also be realized by using the above-described failure recovery method using the path table.

  First, the failure recovery of the partial path D → E5807 will be described. The node E5805 enters a failure recovery operation after detecting a switch failure in the own node, and in the path table, a spare path for the partial path whose own node is the end node is entered. To select the backup path having the highest priority and the normality confirmation performed immediately before, and notify the node B 5802 adjacent to the node E5805 at the branch point node on the backup path. The switching control information 5811 indicating “switching request” is inserted into the APS / PCC byte included in the overhead (OH) information of the signal transmitted to the node B 5802. Thereafter, the switch connection state is changed to the connection to the backup path.

  Node B 5802 that has received the “switch request” from node E 5805 refers to the path table in the same manner as the operation of node B during the above-described failure recovery method procedure, and the node itself is neither the starting node nor the ending node of the partial path. Therefore, when there is no abnormality in the protection path, the signal sent to the node A5801 to notify the adjacent node (here, node A5801) to which the switching control information should be transmitted at the branch point node on the protection path. Is notified by inserting the switching control information 5811 indicating the received “switching request” into the APS / PCC byte included in the overhead (OH) information of the switch, and then the switch connection state is changed to the connection to the protection path. . At this time, since the switching factor of the “switch request” transmitted from the node E 5805 is a node failure (switch failure), the main signal of the connection port to the backup path in the path table is D → A → B → C → It only needs to be set to flow with F.

  After receiving the “switching request” from the node B 5802, the node A 5801 refers to the path table in the same manner as the operation of the node C in the above-described failure recovery method procedure, and the node A 5801 is the start node of the partial path or the end node. However, if there is no abnormality in the protection path, it is sent to the node D5804 in order to notify the adjacent node (node D5804) to which the switching control information should be transmitted at the branch point node on the protection path. This is notified by inserting the switching control information 5811 indicating “switching request” into the APS / PCC byte included in the overhead (OH) information of the existing signal, and then the switch connection state is changed to the connection to the protection path.

  The node D5804 detects the “switching request” from the node A5801, refers to the path table in the same manner as the operation of the node E in the above-described failure recovery method procedure, and since the own node is the starting node of the partial path, When there is no abnormality in the path, the switch connection state is changed to the connection to the protection path, and the adjacent node (to which the switching control information 5812 indicating “switching complete” is to be transmitted at the branch point node on the protection path. Here, in order to notify node A5801), notification is made by inserting switching control information 5812 indicating “switching complete” into the APS / PCC byte included in the overhead (OH) information of the signal transmitted to node A5801.

  In the node A5801, after receiving the “switching completion” from the node D5804, the “switching request” transferred to the node D5804 is changed to the value of the normal state, and thereafter, the “switching completion” is set to the node B5802 Forward. In addition, after receiving “switching complete” from the node A 5801, the node B 5802 changes the “switching request” transferred to the node A 5801 to a normal state value, and then sends a “switching complete” to the node E5805. ". Thereby, the failure recovery of the partial path D → E5807 is completed.

  Next, the failure recovery of the partial path E → F5808 will be described. Similarly to the example of the transmission path failure, the branch point node F5806 detects a failure (a switch failure spillover failure of the node E5805), and then the path table in its own node. Since the local node is the end node of the partial path, the backup path with the highest priority is selected from the backup paths that have been confirmed to be normal before the failure occurred, and branching is performed on the backup path. Switching control information 5813 indicating “switching request” in the APS / PCC byte included in the overhead (OH) information of the signal transmitted to the node C5803 in order to notify the node C5803 adjacent to the node F5806 at the point node Notify by inserting. The “switching request” inserted at this time has a lower priority than the “switching request” issued at the node E5805. Thereafter, the switch connection state is changed to the connection to the backup path.

  For the branch point node C5803 that has received the “switching request” from the node F5806, the path table is referred to in the same way as the operation of the node C in the above-described failure recovery method procedure, and even if the local node is the starting node of the partial path Since it is not a node, when there is no abnormality in the backup path, in the same manner as in node F, the branch point node on the backup path notifies the adjacent node (here, node B5802) to which switching control information is to be transmitted. , The switching control information 5813 indicating “switching request” is inserted into the APS / PCC byte included in the overhead (OH) information of the signal transmitted to the node B 5802, and then the connection state of the switch is set as a backup path. Change to connection to.

  When receiving a “switching request” from the node C5803, the node B5802 refers to the path table and performs the same operation as the node C5803 because the own node is neither the starting node nor the ending node of the partial path. Since the priority of the switching control information indicating the “switching request” received from the node E5805 at the time of the failure recovery from D → E5807 is higher, the connection of the backup path (switch connection change in the own node) should not be performed. Instead, only the “switch request” is transferred. That is, when there is no abnormality in the protection path, the signal sent to the node E5805 to notify the adjacent node (here, the node E5805) to which the switching control information should be transmitted at the branch point node on the protection path. This is notified by inserting switching control information 5813 indicating “switching request” into the APS / PCC byte included in the overhead (OH) information.

  The node E5805 receives the switching control information 5813 indicating the “switching request” from the node B5802, and then refers to the path table to recognize that the own node is the starting node of the partial path E → F5808. Because the cause of the above is lower in priority than the failure detected in the own node, the connection of the backup path (switch connection change in the own node) is not performed, and only the “switching completion” is issued. That is, in order to notify each branch point node on the protection path that the switching has been completed, the switching control information is included in the overhead (OH) information of the signal transmitted to the adjacent node (node B 5805 in this case). This is notified by inserting switching control information 5814 indicating “switching complete” in the APS / PCC byte.

  In the node B5802, after receiving the “switching completion” from the node E5805, the “switching request” transferred to the node E5805 is changed to the value of the normal state, and then received to the node C5803 from the node E5805. Transfer the completed “switch completed”. In addition, after receiving the “switching completion” from the node B 5802, the node C 5803 changes the “switching request” transferred to the node B 5802 to a value in the normal state, and then the node F 5806 receives the “switching completion”. ". Thereby, the failure recovery of the partial path E → F5808 is completed. As for the insertion of the switching control information, the information from the node that issued the “switching request” or “switching complete” can be processed by using the MFAS byte in the same way as the failure recovery method.

  The method described above is the ITU-T recommendation G.264. This is a case where switching control information is exchanged using the APS / PCC byte in the OTN frame in 709. The present invention can also be applied to a cross-connect device using an SDH frame conforming to 707 and a network in which the cross-connect device is arranged in a mesh shape.

It is a figure which shows the structural example of the cross-connect apparatus which can apply this invention. It is a figure which shows the structural example of the mesh network which can apply this invention. It is a figure which shows the structural example of the optical cross-connect apparatus which can apply this invention. It is a figure which shows the example of the form of the conventional network. ITU-T Recommendation G. 7 is a diagram for explaining the contents of an OTN frame defined in 709. FIG. It is a figure explaining the outline | summary of the Example of this invention. It is a figure explaining the Example of this invention. It is a figure explaining an example of the information which each apparatus in this invention has. It is a figure explaining the Example of this invention. It is a figure explaining an example of the path table data in this invention. It is a figure explaining an example of the path table data in this invention. It is a figure explaining an example of the switching control information in the Example of this invention. It is a figure which shows the structural example of the cross-connect apparatus applied to this invention (The normality confirmation method of a backup path, and the line | wire relief method using the same). It is a figure which shows the concept of the structure of a mesh network to which this invention (the normality confirmation method of a backup path, and a line relief method using the same), and a working path, a partial path, and a backup path are applied. It is an example of a delivery method of a path table in the present invention (a protection path normality confirmation method and a line repair method using the same) and an example of a path table configured in a memory of a monitoring control unit in a node. It is a figure which shows the example of a structure of a path table required for the normal check of a backup path, and failure recovery in this invention (The normality check method of a backup path, and a line | wire relief method using the same). FIG. 11 is a diagram (part 1) illustrating an example of a configuration of information regarding a backup path in a path table; FIG. 10 is a second diagram illustrating a configuration example of information regarding a backup path in a path table; FIG. 10 is a diagram illustrating a configuration example of information related to a backup path in a path table (No. 3); It is a figure which shows the structural example of the node table which shows the information regarding a node. It is a figure which shows the example of the transfer route about the normality confirmation information of a backup path in this invention (The normality confirmation method of a backup path, and the line | wire relief method using the same). It is an example (OTN frame and overhead defined in ITU recommendation G.709) of protection path normality confirmation information in the present invention (protection path normality confirmation method and line repair method using the same). It is an example of bit assignment of the MFAS byte and the APS / PCC byte used at the time of checking the normality of the backup path in the present invention (the backup path normality checking method and the line repair method using the same). It is an example of a definition of the value to be set in the APS / PCC byte used when checking the normality of the protection path in the present invention (the protection path normality confirmation method and the line repair method using the same). In the present invention (protection path normality confirmation method and line remedy method using the same), an example of the concept when the backup signal normality confirmation procedure is based on the branch point node on the main signal transmission side is there. Example of protection path normality confirmation procedure, example of normality confirmation information and confirmation response flow, and normality in APS / PCC byte in the present invention (protection path normality confirmation method and line repair method using the same) It is an example (the 1) of the value of confirmation information and confirmation response information. Example of protection path normality confirmation procedure, example of normality confirmation information and confirmation response flow, and normality in APS / PCC byte in the present invention (protection path normality confirmation method and line repair method using the same) It is an example (the 2) of the value of confirmation information and confirmation response information. Example of protection path normality confirmation procedure, example of normality confirmation information and confirmation response flow, and normality in APS / PCC byte in the present invention (protection path normality confirmation method and line repair method using the same) It is an example (the 3) of the value of confirmation information and confirmation response information. It is an example of the correlation about the item in a path table in this invention (The normality confirmation method of a backup path, and the line | wire relief method using the same). In the present invention (protection path normality confirmation method and line repair method using the same), an example of association for each item of the path table in the node E and an example of the reference order when the normality of the protection path is confirmed is there. Correspondence between path table value in node E and interface unit and switch unit in node E when normality of backup path is confirmed in the present invention (protection path normality confirmation method and line repair method using the same) It is an example. It is an example of the procedure (flow) in the node E at the time of confirmation of the normality of a backup path in the present invention (protection path normality confirmation method and line repair method using the same). It is an example about transmission / reception of the normality confirmation information and confirmation response information from the node E at the time of the normality confirmation of a backup path in this invention (the normality confirmation method of a backup path, and a line relief method using the same). In the present invention (protection path normality confirmation method and line repair method using the same), an example of the association of each item of the path table in the node B and an example of the reference order when the normality of the protection path is confirmed is there. Correspondence between the value of the path table in the node B and the interface unit and the switch unit of the node B when the normality of the backup path is confirmed in the present invention (protection path normality confirmation method and line repair method using the same) It is an example. It is an example of the procedure (flow) in the node B at the time of confirmation of the normality of the backup path in the present invention (protection path normality confirmation method and line repair method using the same). It is an example about transmission / reception of the normality confirmation information and confirmation response information from Node B at the time of confirmation of the normality of a backup path in the present invention (protection path normality confirmation method and line repair method using the same). In the present invention (protection path normality confirmation method and line repair method using the same), an example of association of each item of the path table in the node F and an example of reference order when the normality of the protection path is confirmed is there. Correspondence between the value of the path table in the node F and the interface unit and switch unit of the node F when the normality of the backup path is confirmed in the present invention (protection path normality confirmation method and line repair method using the same) It is an example. It is an example of the procedure (flow) in the node F at the time of confirmation of the normality of a backup path in the present invention (protection path normality confirmation method and line repair method using the same). It is an example about transmission / reception of the normality confirmation information and confirmation response information from the node F at the time of confirmation of the normality of a backup path in the present invention (protection path normality confirmation method and line repair method using the same). It is an example of a failure and a failure factor that may occur in the network. It is an example of the failure recovery procedure with respect to a transmission line failure in the present invention (protection path normality confirmation method and line repair method using the same). It is an example of bit assignment of MFAS byte and APS / PCC byte used at the time of failure recovery in the present invention (protection path normality confirmation method and line repair method using the same). It is an example of a definition of a value to be set in the APS / PCC byte used at the time of failure recovery in the present invention (protection path normality confirmation method and line repair method using the same). FIG. 6 is an example of association and reference order for each item of the path table in the node F at the time of failure recovery in the present invention (protection path normality confirmation method and line repair method using the same). Example of correspondence between path table value in node F and interface unit and switch unit of node F at the time of failure recovery, and failure in the present invention (normality confirmation method of backup path and line repair method using the same) It is an example of the switch connection state before occurrence and after failure recovery. It is an example of the procedure (flow) in the node F at the time of failure recovery in the present invention (a protection path normality confirmation method and a line repair method using the same). 5 shows an example of association and reference order of each item of the path table in node C at the time of failure recovery in the present invention (protection path normality confirmation method and line repair method using the same). Example of correspondence between path table value in node C and interface unit and switch unit of node C at the time of failure recovery, and failure in the present invention (protection path normality confirmation method and line repair method using the same) It is an example of the switch connection state before occurrence and after failure recovery. It is an example of the procedure (flow) in the node C at the time of failure recovery in the present invention (a protection path normality confirmation method and a line repair method using the same). FIG. 6 is an example of association and reference order for each item of the path table in the node B at the time of failure recovery in the present invention (protection path normality confirmation method and line repair method using the same). Example of correspondence between path table value in node B and interface unit and switch unit of node B at failure recovery in the present invention (protection path normality confirmation method and line repair method using the same) and failure It is an example of the switch connection state before occurrence and after failure recovery. It is an example of a procedure (flow) in the node B at the time of failure recovery in the present invention (a protection path normality confirmation method and a line repair method using the same). FIG. 6 is an example of association and reference order of each item of the path table in the node E at the time of failure recovery in the present invention (a backup path normality confirmation method and a line repair method using the same). Example of correspondence between path table value in node E, interface unit and switch unit of node E, and failure at the time of failure recovery in the present invention (protection path normality confirmation method and line repair method using the same) It is an example of the switch connection state before occurrence and after failure recovery. It is an example of the procedure (flow) in the node E at the time of failure recovery in the present invention (protection path normality confirmation method and line repair method using the same). It is an example of the failure recovery procedure with respect to a node failure in the present invention (protection path normality confirmation method and line repair method using the same).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 110 ... Input interface part, 130 ... Switch part, 140 ... Output interface part, 160 ... Switching control information transfer part, 210 ... Optical cross-connect apparatus, 220 ... Wavelength multiplexing apparatus, 230 ... Transmission path, 240 ... User line, 300 ... Optical cross-connect device, 310 ... Optical switch unit, 320 ... Wavelength multiplexing device, 330 ... Network node interface, 340 ... User network interface 350... Control unit 610 Branch node 620 Relay node 630 Transmission path 640 Line 660 Detour route 710 Management device 720: Network management network 740: Path table

Claims (10)

An optical cross-connect device that receives an optical signal from a first transmission path, sets a path, and outputs the received optical signal to a second transmission path,
At least one input interface unit that receives an optical signal from the first transmission path and extracts switching control information included in the received optical signal;
An optical switch unit configured to set the path of the received optical signal;
At least one output interface unit for outputting an optical signal from the optical switch unit to the second transmission line;
A switching control information transfer unit that transfers the switching control information extracted by the predetermined input interface unit to the predetermined output interface unit ;
It consists of a path table that stores switching reference information ,
The output interface unit multiplexes the switching control information from the switching control information transfer unit with the optical signal from the optical switch unit, and outputs the multiplexed signal to the second transmission path ,
The path table stores priority information for each path as the switching reference information,
The optical cross-connect device , wherein the switching control information is transmitted / received based on the priority information . The optical cross-connect device according to claim 1,
The optical signals transmitted and received on the first and second transmission lines are ITU-T recommendation G.264. An optical cross-connect device that is transferred using an OTN frame in 709. The optical cross-connect device according to claim 2,
The optical cross-connect device, wherein the switching control information is an APS / PCC byte defined as overhead information of the recommendation. The optical cross-connect device according to any one of claims 1 to 3,
The switching control information is
Detour route information indicating the detour route of the circuit,
An optical cross-connect device including repair node information indicating a node involved in line repair. A cross-connect device that receives a signal from a first transmission path, sets a path, and outputs the received signal to a second transmission path,
At least one input interface unit that receives a signal from the first transmission path and extracts switching control information included in the received signal; a switch unit that sets a path of the received optical signal;
At least one output interface unit for outputting a signal from the switch unit to the second transmission line;
A switching control information transfer unit that transfers the switching control information extracted by the predetermined input interface unit to the predetermined output interface unit ;
It consists of a path table that stores switching reference information ,
The output interface unit multiplexes the switching control information from the switching control information transfer unit with the signal from the switch unit, and outputs the multiplexed signal to the second transmission path ,
The path table stores priority information for each path as the switching reference information,
The cross-connect device , wherein the switching control information is transmitted / received based on the priority information . The cross-connect device according to claim 5,
The signals transmitted and received on the first and second transmission lines are ITU-T recommendation G.264. A cross-connect device that is transferred using an SDH frame in 707. The cross-connect device according to claim 6,
The cross-connect device, wherein the switching control information is an APS byte defined as overhead information of the recommendation. The cross-connect device according to any one of claims 5 to 7,
The switching control information is
Detour route information indicating the detour route of the circuit,
A cross-connect device including rescue node information indicating a node involved in line rescue.   The optical cross-connect device according to claim 2,
  The switching control information is
  An optical cross-connect device comprising MFAS bytes and APS / PCC bytes defined as the overhead information of the recommendation.   The cross-connect device according to claim 6,
  The switching control information is
  A cross-connect device characterized by the MFAS byte and the APS / PCC byte defined as the overhead information of the recommendation.

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