JP2010136299A - Communication system, network management device, network node, communication system control method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system, network management device, network node, communication system control method, and program capable of appropriate path computation when determining a backup resource for a communication line having lost redundancy due to a malfunction. <P>SOLUTION: The communication system for setting a backup resource for a communication line having lost redundancy due to a malfunction has a network management device. The network management device specifies a malfunction place based on a malfunction notification signal transmitted from a node that has detected a network malfunction; sets a given node on a path of the currently used communication line as an endpoint candidate according to the malfunction place; and decides the backup resource based on the results of the path calculation performed based on the endpoint candidate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication system, a network management apparatus, a network node, a communication system control method, and a program for setting a backup resource for a communication line whose redundancy has been lost due to a network failure.

  Conventionally, in an optical communication network, two types of path relief methods have been used in order to improve the reliability against a failure of a logical communication path (path) between nodes.

  One is path recovery. In this method, a working path and a protection path are prepared in advance, and when a failure occurs in the working path, the used path is switched to the protection path. In other words, this is a method of performing relief on a path basis. Here, the path is a logical communication path set in a start node and an end node, a relay node between them, and a link for the purpose of exchanging data. In the following, a path for which recovery by path recovery is set in advance in the event of a failure is referred to as a redundant path.

  The other is link protection. This is an autonomous link repair of a node for a link, such as SONET / SDH protection, in a device such as a wavelength switch or a time division multiplexing device which is a node in a communication network. In other words, this is a method of repairing in units of links, and all paths passing through the corresponding link are repaired. Here, a link is a physical or logical transmission path connecting adjacent nodes, and corresponds to an optical fiber, a SONET / SDH line, or the like. As for link protection, the type of link protection generally set for a link is used in path control as part of the reliability information of the link. Hereinafter, a link for which relief by link protection is preset in the event of a failure is referred to as a redundant link.

  A method for setting the backup path and the backup link (hereinafter collectively referred to as a backup resource) is disclosed in Patent Document 2, for example. In this method, a backup path end point node corresponding to each fault location is set in advance through a centralized management apparatus of the network, and a backup path is set between backup path end point nodes set according to the fault node.

  By the way, even when a backup resource is set on the communication network, if path relief occurs due to a failure, the redundancy of the path or link in which the switching has occurred is lost. As a result, if a failure occurs in the switching destination path or link during the path repair, it cannot be repaired immediately, so that the path reliability decreases. There is also known a method of setting up to further reserve resources in advance, but in this case, about three times as many resources are prepared for one path or link, and network resource utilization efficiency is increased. Will be lower.

  A method for solving this problem is disclosed in Patent Document 1, for example. This method is a path remedy method when multiple failures occur, that is, when a failure occurs simultaneously in the working path (or working link) and the protection path (or protection link). In this method, when a failure occurs in the working path (or working link) and switching to the protection path (or protection link) occurs, the node that detected the failure and switching is switched to the switching destination protection path (or switching destination). A new backup path (or a new backup link) is prepared for the backup link). It is to be noted that the node that detects the switching and prepares a new backup path (or a new backup link) is the node at the end point of the path for path recovery and the node adjacent to the failed link for link protection.

  Here, the operation described in Patent Document 1 will be described below with reference to FIGS. 15 and 16.

  First, the operation in the configuration of FIG. 15 will be described. In FIG. 15, a network is configured by nodes having the configuration described in Patent Document 1, and a link between the nodes 1511 to 1516 is a link having 1: 1 redundancy. Further, it is assumed that paths 1551 having paths of nodes 1511 to 1512 to 1513 to 1514 to 1515 to 1516 are set in the working links 1521 to 1525 between the respective nodes.

  In the network of FIG. 15, for example, when a failure occurs in the link 1523, the adjacent nodes 1513 and 1514 detect it and switch the used link from the working link 1523 to the protection link 1533 based on the 1: 1 link protection setting. Along with this, the path 1551 does not have a spare resource between the nodes 1513 to 1514, and the reliability decreases. In order to prevent the reliability of the path 1551 from being lowered, it is necessary to newly set a backup path. In the following, a new backup path may be referred to as a “new backup path”.

  According to the new backup path setting method disclosed in Patent Document 1, the nodes 1513 and 1514 that have performed link switching attempt to allocate a new backup resource. Specifically, the node 1513 performs routing using the nodes 1513 and 1514 that are adjacent nodes of the failed link as an end point, that is, performs route calculation, and allocates a free resource that can set a new backup path between the nodes 1513 to 1514. look for. In this case, since the links 1541, 1542, and 1543 are free, the routes of the nodes 1513 to 1517 to 1518 to 1514 are found. After that, the node 1513 is set as the starting point, the resources of the new backup path are secured by signaling along the discovered route, and the nodes 1513 and 1514 set the reserved new backup path as the new switching destination of the path 1551 to 1551 new protection path setting is completed.

  In this way, in the case of the network configuration as shown in FIG. 15, the reliability of the existing path 1551 can be prevented from being lowered by the new backup path setting method described in Patent Document 1.

  Next, the operation in the configuration of FIG. 16 will be described. In the case of the network configuration as shown in FIG. 16, the new protection path setting method described in Patent Document 1 cannot prevent the existing path reliability from being lowered. FIG. 16 is similar to FIG. 15 except that the network is configured by nodes having the configuration described in Patent Document 1 as in FIG. 15 and the connection nodes of the links corresponding to the link 1541 and link 1543 in FIG. 15 are different. Network configuration.

  In the network of FIG. 16, for example, when a failure occurs in the link 1623, the adjacent nodes 1613 and 1614 detect it, and the used link is switched from the working link 1623 to the backup link 1633 based on the 1: 1 link protection setting. As a result, the path 1651 does not have a spare resource between the nodes 1613 to 1614, and the reliability decreases. In order to prevent the reliability of the path 1651 from deteriorating, it is necessary to newly set a backup path.

  According to the new backup path setting method of Patent Document 1, the nodes 1613 and 1614 that have performed link switching try to allocate new backup resources. Specifically, the node 1613 performs route calculation using the nodes 1613 and 1614 that are adjacent nodes of the failure link as endpoints, and searches for free resources that can set a new backup path between the nodes 1613 to 1614. Looking at the network topology in FIG. 16, a route 1652 of nodes 1613 to 1612 to 1617 to 1618 to 1615 to 1614 can be candidates as a route of the new backup path with the nodes 1613 and 1614 as endpoints. When it is checked whether there is a free resource to which a new backup path is allocated on the route 1652, the links between the nodes 1612 to 1617 to 1618 to 1615 are free, but the nodes 1613 to 1612 and the nodes 1615 to 1614 are open. That is, there is no empty link in the sections 1661 and 1662. This is because the links 1622 and 1624 have already been assigned to resources for the path 1651 as working links of the path 1651 and the links 1632 and 1634 have been reserved links to the working links 1622 and 1624, respectively. Therefore, the node 1613 cannot find a route between the nodes 1613 to 1614 and fails in route calculation. As a result, the node 1613 determines that there is no backup path that can be newly set. Therefore, the method described in Patent Document 1 cannot prevent a decrease in the reliability of the path 1651 in the configuration shown in FIG.

  On the other hand, as can be seen from the network configuration of FIG. 16, the links 1641, 1642, and 1643 are free, and there are enough resources to allocate a new backup path for the existing path 1651. If the route calculation is performed not between the nodes 1613 to 1614 but between the nodes 1612 to 1615, the route 1652 can be found. Furthermore, if a new backup path is set along the route 1652, a decrease in the reliability of the path 1651 can be prevented.

As described above, in the new protection path setting method described in Patent Document 1, the end point of the new protection path is the node that detected the failure with respect to the path switched to the protection path or protection link due to the failure. Therefore, appropriate route calculation cannot be performed. Therefore, the method described in Patent Document 1 has a problem that, depending on the arrangement of network resources, the allocation of a new spare resource may fail even though the new spare resource can be sufficiently allocated. In addition, as an example of the arrangement of network resources that fail to allocate a new backup resource, as described above, when path recovery is performed by link protection, a free resource that only creates a new backup path between adjacent nodes of the failed link There may be no. Here, 1: 1 link protection is used as an example, but the same applies to other link protection types such as 1: N, 1 + 1, and BLSR ring protection.
Japanese Patent Laying-Open No. 2005-12306 (FIGS. 1, 3, 0012 to 0037, etc.) Japanese Patent Laid-Open No. 2000-324167 (FIGS. 1, 9, 11, etc.)

  The present invention has been made in view of the above circumstances, and when determining a backup resource for a communication line whose redundancy has been lost due to a failure, a communication system capable of calculating an appropriate route, a network management device, a network node, It is an object of the present invention to provide a control method and program for a communication system.

  In order to achieve this object, a communication system according to the present invention is a communication system for setting a backup resource for a communication line whose redundancy has been lost due to a network failure, and is a failure notification sent from a node that has detected the network failure. A fault resource is identified based on the signal, a predetermined node on the path of the working communication line is set as an endpoint candidate according to the fault location, and a spare resource is based on the result of path calculation performed based on the endpoint candidate A network management device for determining

  The network management device of the present invention is a network management device for managing a communication line on a network, a failure location specifying means for specifying a failure location based on a failure notification signal transmitted from a node that has detected a network failure, End point candidate setting means for setting a predetermined node on the path of the active communication line as an end point candidate according to the fault location, and end point spare for determining a spare resource based on the result of the route calculation performed based on the end point candidate Resource determining means.

  The network node according to the present invention is a network node arranged on the network, and when the node detects a network failure and sends a failure detection signal, or when a failure notification signal is received from another node And a notification destination determination means for determining a notification destination of the failure notification signal according to the transmission source of the failure notification signal and the setting status of switching to the spare resource in the own node.

  The communication system control method of the present invention is a communication system control method for setting a backup resource for a communication line whose redundancy has been lost due to a network failure, and is sent from a node that has detected a network failure. Based on the result of the route calculation performed based on the endpoint candidate, the failure location is identified based on the failure notification signal, the predetermined node on the path of the active communication line is set as the endpoint candidate according to the failure location And reserve resources are determined.

  As a first aspect, the program of the present invention is a program for setting a backup resource for a communication line whose redundancy has been lost due to a network failure, and includes a failure notification signal transmitted from a node that has detected the network failure. Fault location identification processing for identifying a fault location based on the endpoint, endpoint candidate setting processing for setting a predetermined node on the current communication line route as an endpoint candidate according to the failure location, and a route performed based on the endpoint candidate It is characterized by causing a computer to execute endpoint spare resource determination processing for determining a spare resource based on a calculation result.

  As a second aspect, the program of the present invention, when detecting a network failure at its own node and sending a failure detection signal, or when receiving a failure notification signal from another node, the source of the failure notification signal And a notification destination determination process for determining a notification destination of a failure notification signal in accordance with a setting state of switching to a spare resource in the own node.

  According to the present invention, when determining a backup resource for a communication line whose redundancy has been lost due to a failure, an appropriate route calculation can be performed.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 shows the configuration of a communication system according to the first embodiment of the present invention. The communication system in FIG. 1 includes a plurality of nodes (network nodes) 121 to 128 and a centralized management device (network management device) 111, and a path 161 passing through the nodes 121 to 126 is set. The links 131 and 141 are set as link pairs having 1: 1 redundancy of the working link and the protection link, respectively. The same applies to the links 132 and 142 to the links 135 and 145. The links 151 to 153 are empty links, and a new path passing through them can be set.

  When a failure occurs in the adjacent link (link adjacent to the node), the nodes 121 to 126 send a failure notification signal to the centralized management device 111. Further, switching to a backup link may be performed by a path relief method set in advance.

  The centralized management device 111 identifies the failure location based on the failure notification signal received from the node. Thereafter, the centralized management apparatus 111 determines a new backup path for the path 161 in accordance with the identified failure location.

  A configuration example of each of the nodes 121 to 126 of the communication system according to the first embodiment is shown in FIG. The nodes 121 to 126 in FIG. 2 include a failure detection unit 21, a node control unit 22, a resource switching unit 23, and a failure notification signal transmission / reception unit 24.

  The failure detection unit 21 detects a failure of a link (adjacent link) connected to the own node and notifies the node control unit 22 of a failure notification signal.

  Upon receiving the failure notification signal from the failure detection unit 21, the node control unit 22 instructs the resource switching unit 23 to switch resources when switching to a spare resource in the own node is set in advance. Further, the node control unit 22 sends a failure notification signal to another device (centralized management device, other node) through the failure notification signal transmission / reception unit 24.

  The resource switching unit 23 switches to a spare resource according to the resource switching instruction from the node control unit 22.

  When the failure notification signal transmission / reception unit 24 receives the failure notification signal from the node control unit 22, the failure notification signal transmission / reception unit 24 transmits the failure notification signal to other devices (centralized management device, other nodes). The failure notification signal transmission / reception unit 24 receives a failure notification signal sent from another node and sends it to the node control unit 22.

  A configuration example of the centralized management apparatus of the communication system according to the first embodiment is shown in FIG. 3 includes a failure notification signal receiving unit 30, a failure notification analysis unit 31, a backup path creation determination unit 32, a route calculation unit 33, a link information database (DB: Data Base) 34, an existing And a path information database (DB: Data Base) 35.

  The failure notification signal receiving unit 30 receives a failure notification signal sent from a failure detection node (a node that has detected a failure) and sends the failure notification signal to the failure notification analysis unit 31.

  The failure notification analysis unit 31 analyzes the failure notification signal sent from the failure notification signal reception unit 30, identifies the failure location (location where the failure has occurred), and provides the failure location information indicating the identified failure location as a backup path. The creation determination unit 32 is notified. The failure notification analysis unit 31 can be called failure location specifying means.

  The protection path creation determination unit 32 identifies an existing path (a path currently in use) that needs to be newly set up based on the failure location information indicating the failure location notified from the failure notification analysis unit 31. . Further, the backup path creation determination unit 32 also sets end point candidates for the new backup path of each existing path, and also instructs the node when a new backup path route is found, to set a new backup path. The backup path creation determination unit 32 can be called an end point candidate setting unit and a backup resource determination unit.

  The route calculation unit 33 uses the link information database 34 to calculate a route between the end point candidates set by the backup path creation determination unit 32.

  The link information database 34 stores topology information regarding nodes and the like arranged on the network. Specific examples of the topology information include node information regarding nodes and link information regarding links. Note that the link information includes what redundancy each link has.

  The existing path information database 35 stores route information related to routes set on the network. Specific examples of route information include existing path information related to nodes and links through which existing paths pass, and backup path information related to nodes and links through which backup paths of existing paths pass.

  Next, the operation of the communication system according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a communication system according to the first embodiment of the present invention as described above. FIG. 4 is a flowchart showing the operation of the communication system of the present invention.

  In the communication system of FIG. 1, for example, when a failure occurs in the link 133, the nodes 123 and 124 detect it and switch to the backup link 143 (S41). In addition, the nodes 123 and 124 send a failure notification signal to the central management apparatus 111. The failure notification signal is a signal that is used in the centralized management device 111 to identify a location where a failure has occurred (failure location). Examples include node identifiers and node connection interface identifiers (link identifiers). For example, when a failure occurs in the link 133, the content of the failure notification signal is a set of the identifiers of the nodes 123 and 124 that have detected the failure and the identifier of the connection interface to the link 133 of those nodes.

  The centralized management apparatus 111 holds an identifier (node information) of each node of the network and an identifier (link information) attached to the connection interface to the link as the link information database 34. Therefore, the centralized management device 111 searches the link information database 34 based on the received failure notification signal, thereby specifying the link where the failure has occurred and obtaining link information of the specified link.

  In addition, when the network node is a node that transparently transmits an optical communication signal (described later in the sixth embodiment), in addition to the content of the failure notification signal (node and connection interface identifier) described above, Whether the failure detection signal is an OSC (Optical Supervisory Channel) signal is included. The centralized management device 111 uses only the failure notification signal based on the OSC signal for specifying the failure location. Here, the OSC signal is a monitoring signal that is terminated for each of two devices connected by an optical fiber in a wavelength division multiplexing network.

  In the case of FIG. 1, the centralized management apparatus 111 receives a failure notification signal including an identifier for specifying the link 133 from the node 123 and the node 124. Then, it is determined that the failure location is only the link 133 (S42). In FIG. 1, the failure location is only one link, but the failure location may be a plurality of links. For example, when a failure occurs in a node itself, all links connected to that node become failure locations.

  Next, the centralized management apparatus 111 sets a new backup path for the path 161 passing through the link 133 that is the identified failure location. The centralized management apparatus 111 first sets the nodes 123 and 124, which are adjacent nodes of the link 133 (nodes connected to the link), as end point candidates of the new backup path (S43), and performs route calculation between the end points (S44). .

  As a result of the route calculation, if the route is not found (S45 / No), the centralized management device 111 sets another node pair through which the path 161 passes as a new endpoint candidate (S451), and again calculates the route. I do. In this way, when the central management apparatus 111 repeats S44 to S451 and performs route calculation using the node 122 and the node 125 as endpoint candidates, for example, the route 162 is found (S45 / Yes). As described above, in the present embodiment, two nodes existing at positions where a failure point is sandwiched are set as endpoint candidates on the route of the active communication line.

  When the route is found (S45 / Yes), the central management apparatus 111 sets a new backup path along the found route 162 (S46). The new backup path set along the route 162 is hereinafter referred to as a new backup path 162. When the setting of the new backup path 162 is completed, the centralized management apparatus 111 sets a switching destination backup resource when a failure occurs next for each node on the path 161 (S47). For example, the centralized management apparatus 111 sets the nodes 122 and 125 to switch to the new backup path 162 when a failure occurs in the link 143.

  The centralized management apparatus 111 stores the correspondence between the failed link and the new backup path, that is, the correspondence between the link 133 and the new backup path 162, and releases the new backup path when the fault is recovered. It may be used. In the communication system of FIG. 1, when the failure of the link 133 is recovered, the nodes 123 and 124 that are adjacent nodes of the link 133 notify the centralized management apparatus 111 of a recovery notification signal. The centralized management device 111 specifies that the recovery location is the link 133 based on the received recovery notification signal in the same manner as in the case of link failure detection. Alternatively, the network operator may input to the central management apparatus 111 that the link 133 has been restored. When the centralized management device 111 knows that the failure of the link 133 has been recovered, the new backup path is transferred to the node 122 that is the starting point node of the new backup path 162 from the stored correspondence relationship between the link 133 and the new backup path 162. Command to release 162 resources. As a result, the resources of the new backup path 162 are released, and the links 151 to 153 can use other paths.

  Here, as an example, the case where the link through the path has 1: 1 redundancy has been described, but the same applies to other link protection types such as 1: N, 1 + 1, and BLSR ring protection.

  Next, the operation of each node of the communication system according to the first embodiment will be described with reference to FIGS. As shown in FIG. 2, when a failure occurs in an adjacent link of a node, the failure detection unit 21 detects the failure (S51) and sends a failure notification signal to the node control unit 22.

  When the node control unit 22 that has received the failure notification signal is set to switch to a spare resource in its own node for the notified failure (S52 / Yes), the resource switching unit 23 switches to the spare resource. In response to this, the resource switching unit 23 switches to the spare resource (S521).

  After the switching instruction to the spare resource or when the switching to the spare resource in the own node is not set (S52 / No), the node control unit 22 passes through the failure notification signal transmission / reception unit 24, and the centralized management apparatus And a fault communication signal is transmitted to the adjacent node opposite to the fault link on the path of the path passing through the fault location (S53).

  The operation when the node control unit 22 receives a failure notification signal from another node (S51) is the same as the operation after receiving the failure notification signal from the failure detection unit 21 of the own node.

  The operation of the centralized management apparatus of the communication system according to the first embodiment will be described with reference to FIGS. When a failure notification signal is received from the failure detection node via the failure notification signal reception unit 30 (S10), the failure notification analysis unit 31 identifies a failure location based on the failure notification signal (S11). The specific method is as described in the operation of the communication system according to the present embodiment.

  Next, the failure notification analysis unit 31 notifies the protection path creation determination unit 32 of failure location information indicating the identified failure location (S12).

  The backup path creation determination unit 32 refers to the notified failure location information, the link information database 34, and the existing path information database 35, and identifies an existing path (path 161 in the example of FIG. 1) that passes through the failure location ( S13). The link information database 34 stores network topology information (node information and link information). The existing path information database 35 stores network route information (existing path information and backup path information).

  The backup path creation determination unit 32 refers to the link information database 34 to identify a link whose redundancy has been lost due to a failure, and further refers to the existing path information database 35 so as to pass through the existing path. (A path whose redundancy has been lost as a result of link protection) or an existing path whose redundancy has been lost due to a failure (a path whose redundancy has been lost as a result of path recovery) is identified. For this existing path, the protection path creation determination unit 32 sets endpoint candidates to set a new protection path (S14), and requests the route calculation unit 33 to perform route calculation (S15). As a method for setting endpoint candidates, for example, there is a method described in detail in the description of a fourth embodiment of the present invention described later.

  Receiving the route calculation request, the route calculation unit 33 performs the requested calculation (S16), and returns the calculation result to the backup path creation determination unit 32 as a route calculation response (S17).

  If the route calculation response includes the route of the new protection path, the protection path creation determining unit 32 instructs the start node of the new protection path to set the new protection path along the route (S18). . When the route calculation response does not include the route of the new backup path, the route calculation has failed, and therefore the backup path creation determination unit 32 sets another node as a new endpoint candidate and again sends a route calculation request to the route calculation unit. Send to 33.

  In the present embodiment, the route calculation is performed by the centralized management device 111. However, the route calculation may be performed by a device other than the centralized management device 111. For example, there is a case where a path calculation server such as PCE (Path Computation Element) is used. In this case, as another device, a server having the function of the route calculation unit 33 of FIG. 3 and the function of communicating with the centralized management device 111 is arranged on the network. The central management apparatus 111 makes a route calculation request shown in S15 of FIG. 6 to the server. At this time, the centralized management apparatus 111 transmits the endpoint candidate information indicating the endpoint candidates to the server and permits the server to access the link information database 34. When the server receives the route calculation request and the endpoint candidate information, the server accesses the link information database 34 of the central management apparatus 111. Then, similarly to the route calculation unit 33, the server uses the link information database 34 to calculate a route between the endpoint candidates indicated by the endpoint candidate information. The server may be provided with the link information database 34 shown in FIG. Thereafter, the server transmits the route calculation result to the centralized management apparatus 111. The centralized management device 111 makes a determination based on the received route calculation result (FIG. 4 / S45). If a route is found, a new backup path is set for the route (FIG. 4 / S46). If it is not found, another node is used as an end point candidate, and a route calculation is requested to the server again (FIG. 4 / S451).

[Second Embodiment]
FIG. 7 shows the configuration of a communication system according to the second embodiment of the present invention. The communication system of FIG. 7 includes a plurality of nodes 721 to 728 and a centralized management device 711 as in FIG. 1, but the node 727 is adjacent to 723 instead of 722, and the node 728 is not 725. 1 is different from FIG.

  The configurations of the nodes 721 to 728 and the centralized management apparatus 711 are the same as those described in the first embodiment, and thus description thereof is omitted here.

  Next, the operation of the communication system according to the second exemplary embodiment of the present invention will be described with reference to FIGS. In the communication system of FIG. 7, for example, when a failure occurs in the link 733, the nodes 723 and 724 detect the failure and switch to the backup link 743 (S41). In addition, the nodes 723 and 724 send a failure notification signal to the central management apparatus 711.

  The centralized management device 711 identifies a failure location by the same method as in the first embodiment based on the received failure notification signal (S42). Here, the failure location is the link 733.

  Next, the centralized management apparatus 711 sets a new backup path for the path 761 passing through the link 733 that is the identified failure location. Nodes 723 and 724 that are adjacent nodes of the link 733 are set as end point candidates of the new backup path (S43), and a route calculation between the end points is performed (S44).

  As a result of the route calculation, a route 762 is found. The operation after the path 762 is found is the same as the operation after the central management apparatus 111 finds the path 162 in the communication system of FIG.

  Also, the operations of the nodes and the centralized management apparatus of the communication system according to the second embodiment are the same as those described in the first embodiment, and a description thereof is omitted here.

[Third Embodiment]
FIG. 8 shows the configuration of a communication system according to the third embodiment of the present invention. The communication system in FIG. 8 includes a plurality of nodes 821 to 828 and a centralized management device 811 as in FIG. 1, but the node 827 is adjacent to 823 instead of 822 as in FIG. Different.

  Since the configurations of the nodes 821 to 828 and the centralized management device 811 are the same as those described in the first embodiment, description thereof is omitted here.

  Next, the operation of the communication system according to the third embodiment of the present invention will be described with reference to FIGS. In the communication system of FIG. 8, for example, when a failure occurs in the link 833, the nodes 823 and 824 detect it and switch to the backup link 843 (S41). In addition, the nodes 823 and 824 send a failure notification signal to the centralized management device 811.

  The centralized management device 811 identifies the failure location by the same method as in the first embodiment based on the received failure notification signal (S42). Here, the failure location is the link 833.

  Next, the centralized management apparatus 811 sets a new backup path for the path 861 passing through the link 833 that is the identified failure location. Nodes 823 and 824 that are adjacent nodes of the link 833 are set as end point candidates of the new backup path (S43), and a route calculation between the end points is performed (S44).

  As a result of the route calculation, if a route is not found (S45 / No), another pair of nodes through which the path 861 passes is set as a new endpoint candidate (S451), and the route calculation is performed again. In this way, S44 to S451 are repeated, and the route calculation is performed using the node 823 and the node 825 as endpoint candidates.

  As a result of the route calculation, a route 862 is found. The operation after the path 862 is found is the same as the operation after the central management apparatus 111 finds the path 162 in the communication system of FIG.

  Also, the operations of the nodes and the centralized management apparatus of the communication system according to the third embodiment are the same as those described in the first embodiment, and thus description thereof is omitted here.

  As described above, in the first to third embodiments of the present invention, since the centralized management device identifies a fault location and sets endpoint candidates, a new spare resource for a communication line whose redundancy has been lost is allocated. When determining, an appropriate route calculation can be performed. Therefore, the reliability of the path can be improved.

[Fourth Embodiment]
In the fourth embodiment of the present invention, in the communication system of any one of the first to third embodiments, a route is found when the central management apparatus designates the next endpoint candidate node in S451 of FIG. Another node located in the direction away from the fault location is designated as a new end point with respect to the end point candidate that did not exist.

  The configuration example of the communication system according to the fourth embodiment of the present invention is any one of FIG. 1, FIG. 7, and FIG. 8, and the configuration of the node and the centralized management apparatus is the same as that described in the first embodiment. It is. Therefore, the description here is omitted.

  The operation of the communication system according to the fourth embodiment will be described with reference to FIG. 1, FIG. 4, and FIG. In the communication system of FIG. 1, for example, after a failure occurs in the link 133, the centralized management apparatus 111 sets the nodes 123 and 124 as end point candidates for the new backup path and calculates the route between the end points (S41 to S44). ) Is as described in the first embodiment.

  In FIG. 1, since the route between the nodes 123 and 124 is not found (S45 / No), the central management apparatus 111 sets another node pair as a new endpoint candidate (S451). Here, the following method is taken as an example of the end point candidate designation. Initially, nodes 123 (new backup path start point candidates) and 124 (new backup path end point candidates) for which link switching has been performed are designated. If the backup path route is not found, the new backup path start point candidate is fixed at the node 123, and the new backup path end point candidate is sequentially shifted from the node 124 along the path 161 to the new backup path 125 and 126. Search for a path. If the backup path route is not found even if this is repeated up to 126, which is the end node of the path 161, the new backup path start point candidate is shifted from the node 123 to 122, which is an adjacent node on the path 161. Then, the calculation is performed while sequentially shifting the new backup path end point candidates from 124 to 126 in the same manner as described above to search for a new backup path. This is repeated until the new backup path route calculation for all node pairs on the path 161 is completed. If the new backup path route is still not found, the central management apparatus 111 determines that a new backup path cannot be set.

  If the method described above is followed, the centralized management apparatus 111 performs calculations for all possible end point candidates, so that the effect of finding a new backup path as much as possible is obtained. That is, a backup path can be appropriately set regardless of the arrangement of network resources. According to the above method in FIG. 1, the centralized management device 111 sequentially designates endpoint candidates between the nodes 123 and 124, between the nodes 123 and 125, between the nodes 123 and 126, between the nodes 122 and 124, between the nodes 122 and 125, and so on. Repeat the route calculation. Then, when the route calculation is performed between the nodes 122 and 125, the centralized management device 111 finds the route 162. FIG. 9 shows the result of repeating the end point designation and the backup path route calculation until the centralized management apparatus 111 finds the route 162 in this way. Since the operation after the centralized management apparatus 111 finds the path 162 is the same as that described in the first embodiment, a description thereof is omitted here.

  Here, the operation of the communication system of FIG. 1 has been described as an example, but the above method can be similarly applied when the communication system has the configuration of FIG. 7 or FIG.

  Since the operation of the node of the communication system according to the fourth embodiment is the same as that described in the first embodiment, a description thereof is omitted here.

  Next, the operation of the centralized management apparatus of the communication system according to the fourth embodiment will be described with reference to FIGS. In FIG. 6, the process until the protection path creation determining unit 32 specifies an existing path for setting a new protection path (S10 to S13) is the same as that described in the first embodiment.

  The protection path creation determination unit 31 designates end point candidates of the new protection path for the specified existing path. If the same endpoint candidate designation method as described in the communication system according to the present embodiment is used, the backup path creation determination unit 31 first designates the nodes 123 and 124 as endpoint candidates (S14), and calculates the route. A route calculation is requested to the unit 33 (S15).

  As described in the communication system according to the present embodiment, since there is no route between the nodes 123 and 124, the route calculation unit 33 returns a route calculation failure notification to the backup path creation determination unit 31 as a response (S16 to S17). ).

  Receiving the route calculation failure response, the backup path creation determining unit 31 next designates the nodes 123 and 125 as end point candidates (S14), and requests the route calculation unit 33 again for route calculation (S15). The route is not found (S16), and the route calculation unit 33 returns a route calculation failure notification (S17). Hereinafter, end point candidate designation and path calculation between the nodes 123 and 126, between the nodes 122 and 125, and between the nodes 122 and 125, that is, the portion surrounded by the dotted line in FIG. 6 is repeated.

  Then, when the route calculation is performed between the nodes 122 and 125 (S16), the route calculation unit 33 finds the route 162 and notifies the backup route creation determination unit 31 of the resulting route 162 (S17).

  The backup path creation determination unit 31 that has received the notification of the path 162 instructs the start node of the new backup path to set a new backup path along the path, as described in the first embodiment. (S18). The starting point node of the new backup path here is the node 122 that is the starting point of the route 162.

  In the above description, an example of the method for specifying an end point is given, but other methods may be used. In the above example, the calculation is performed while sequentially shifting the new backup path end point candidate and the start point candidate one node at a time. However, the calculation may be performed while sequentially shifting the plurality of nodes on the backup path route. In the above example, the calculation is performed while fixing the start point candidate or the end point candidate and shifting the end point candidates. However, the calculation may be performed while simultaneously shifting the start point candidate or the end point candidate.

[Fifth Embodiment]
According to a fifth embodiment of the present invention, in each communication system according to any one of the first to fourth embodiments, each network node performs optical-electrical conversion on a communication signal and detects a network failure or other When a failure notification signal is received from a node, it has means for determining a notification destination device of the failure notification signal by comparing the content of the failure notification signal with a preset criterion.

  An example of the configuration of a communication system according to the fifth embodiment of the present invention is shown in FIG. FIG. 10 includes a plurality of nodes 1021 to 10212 and a central management apparatus 1011, and a path 1061 passing through the nodes 1021 to 1026 is set. The links 1031 and 1041 are set as link pairs having 1: 1 redundancy of the working link and the protection link, respectively. The same applies to the links 1032 and 1042 to the links 1037 and 1047. The links 1051 to 1056 are empty links, and a new path passing through these links can be set. When a failure occurs in the adjacent link, the nodes 1021 to 10212 compare the content of the failure notification signal with a predetermined criterion (FIG. 13), and notify the central management device and other nodes of the failure notification signal. Alternatively, it is determined not to notify, and a failure notification signal is transmitted based on the determination. There is a case where switching to a backup link is performed by a path relief method set in advance. The centralized management apparatus 1011 identifies the failure location based on the failure notification signal received from the node. Thereafter, the centralized management apparatus 1011 determines a new backup path for the path 1061 according to the identified failure location.

  A configuration example of each node of the communication system according to the fifth embodiment is shown in FIG. The node in FIG. 11 includes a failure detection unit 1111, a node control unit 1112, a resource switching unit 1113, and a failure notification transmission / reception unit 1114, and has a failure notification destination determination unit 1115 in the node control unit 1112. And

  The failure detection unit 1111, resource switching unit 1113, and failure notification transmission / reception unit 1114 have the same functions as the failure detection unit 21, resource switching unit 23, and failure notification signal transmission / reception unit 24 of FIG. 2, respectively. Therefore, the description here is omitted.

  When the node control unit 1112 receives a failure notification signal from the failure detection unit 1111 or another node and sends a failure notification signal to another device, the node control unit 1112 does not determine the notification destination itself, but the failure notification destination determination unit 1115. 2 is different from the node control unit 22 of FIG. 2 in that a notification of a notification destination is requested and a failure notification signal is sent to the notification destination determined by the failure notification destination determination unit 1115. Further, the failure notification destination determination unit 1115 compares the content of the failure notification signal with a predetermined determination criterion (FIG. 13) when the node control unit 1112 is requested to determine the notification destination of the failure notification signal. The notification destination device of the failure notification signal is determined. The failure notification destination determination unit 1115 can be referred to as notification destination determination means.

  The configuration of the central management device of the communication system according to the fifth embodiment is the same as that described in the first and fourth embodiments. Therefore, the description here is omitted.

  The operation of the communication system according to the fifth exemplary embodiment of the present invention will be described with reference to FIGS. 4, 10, and 13. 4 is a flowchart of the overall operation of the communication system according to the fifth embodiment, FIG. 10 is a configuration of the communication system according to the fifth embodiment, and FIG. 13 is a failure notification signal transmission destination in a node of the communication system according to the fifth embodiment. It is a judgment standard.

  In FIG. 10, for example, when a failure 1 occurs in the link 1034, the nodes 1024 and 1025 detect the failure. Further, since the nodes 1024 and 1025 are set to switch to the backup link 1044 in response to the failure of the link 1034, the used link is switched according to the setting (S41). In FIG. 10, since the nodes 1024 and 1025 detect the failure of the link 1034 and switch to the backup link, the nodes 1024 and 1025 send a failure notification signal only to the centralized management apparatus 1011 according to the criteria of FIG.

  The centralized management apparatus 1011 that has received the failure notification signal identifies a failure location and determines a backup resource as in the first embodiment, and sets a new backup path 1062 along the path 1062 (S42 to S46). When the setting of the new backup path is completed, the centralized management apparatus 1011 sets the switching destination backup resource when the next failure occurs for each node on the path 1061 (S47). In FIG. 10, the nodes 1023 and 1026 are set to switch to the new backup path 1062 when a failure occurs in the link 1044.

  Next, an operation when failure 2 occurs in the link 1044 in a state where failure 1 is not recovered in FIG. 10 will be described. For example, when a failure 2 occurs in the link 1044, the nodes 1024 and 1025 detect this. Since the nodes 1024 and 1025 are not set to switch to the spare resource in response to the failure of the link 1044, the failure management signal 1012 and other devices are transmitted according to the criteria of FIG. To (adjacent node). Here, the node 1024 sends a failure notification signal to the centralized management apparatus 1011 and the node 1023, and the node 1025 sends a failure notification signal to the centralized management apparatus 1011 and the node 1026.

  Receiving the failure notification signal, the nodes 1023 and 1026 check whether or not switching to the spare resource in the own node is set for the failure content. As described in the operation when the failure 1 occurs, since the nodes 1023 and 1026 are set to switch to the new backup path 1062 when the failure occurs in the link 1044, the nodes 1023 and 1026 Switching to the new backup path 1062 is performed in accordance with the criteria of FIG. Further, since the nodes 1023 and 1026 have switched to the spare resource in the own node in response to the failure described in the failure notification signal received from the other node, the failure notification is sent to the other devices as shown in FIG. do not send.

  On the other hand, the centralized management apparatus 1011 that has received the failure notification signal identifies the failure location and determines the backup resource, as in the first embodiment, and sets a new backup path 1063 along the path 1063 (S42 to S46). ). When the setting of the new backup path is completed, the centralized management apparatus 1011 sets the switching destination backup resource when the next failure occurs for each node on the path 1062 (S47). In FIG. 10, the nodes 1022 and 1027 are set to switch to the new backup path 1063 when a failure occurs in any of the links 1051, 1052, and 1053.

  The operation of each node of the communication system according to the fifth embodiment will be described with reference to FIG. 11, FIG. 12, and FIG. FIG. 11 is a configuration example of the node, FIG. 12 is a flowchart of the operation of the node, and FIG.

  As shown in FIG. 11, when a failure occurs in an adjacent link of a node, the failure detection unit 1111 detects the failure (S121) and sends a failure notification signal to the node control unit 1112.

  The node control unit 1112 that has received the failure notification signal sets the resource switching unit 1113 to the spare resource when switching to the spare resource in the own node is set for the notified failure (S122 / Yes). In response to this, the resource switching unit 1113 switches to the spare resource (S1221).

  After the switching instruction to the spare resource or when the switching to the spare resource in the own node is not set (S122 / No), the node control unit 1112 sends a fault notification signal to the fault notification destination determination unit 1115. Send and request judgment of failure notification destination. Upon receiving the failure notification destination determination request, the failure notification destination determination unit 1115 determines the failure notification destination by comparing the content of the failure notification signal with the preset determination criteria shown in FIG. 13 (S123). The notification destination is sent to the node control unit 1112.

  The node control unit 1112 sends a failure notification signal to the failure notification destination received from the notification destination determination unit 1115 (S124). Further, the operation when the node control unit 1112 receives a failure notification signal from another node (S121) is the same as the operation after receiving the failure notification signal from the failure detection unit 1111 of its own node. The description here is omitted.

  The operation of the centralized management apparatus of the communication system according to the fifth embodiment is the same as that described in the first and fourth embodiments. Therefore, the description here is omitted.

[Sixth Embodiment]
An example of the configuration of a communication system according to the sixth embodiment of the present invention is shown in FIG. Each node is the same as that described in the fifth embodiment, except that the optical communication signal is transmitted transparently and the determination criterion of the failure notification destination is different.

  Since the configuration of each node of the communication system according to the sixth embodiment is the same as that described in the fifth embodiment, description thereof is omitted here. In addition, the configuration of the centralized management apparatus of the communication system according to the sixth embodiment is the same as that described in the first and fourth embodiments, and thus description thereof is omitted here.

  Operation of the communication system according to the sixth exemplary embodiment of the present invention will be described with reference to FIGS. 4, 10, and 14. 4 is a flowchart of the operation of the entire communication system according to the sixth embodiment, FIG. 10 is a configuration of the communication system according to the sixth embodiment, and FIG. 14 is a failure notification signal transmission destination in a node of the communication system according to the sixth embodiment. It is a judgment standard.

  In FIG. 10, for example, when a failure 1 occurs in the link 1034, in the sixth embodiment, all the nodes on the path passing through the link 1034 detect the failure. However, unlike the other nodes, the nodes 1024 and 1025 that are adjacent nodes of the link 1034 can be identified as the link 1034 by the OSC signal. As in the fifth embodiment, the nodes 1024 and 1025 that have detected a failure by the OSC signal switch the used link from 1034 to 1044 (S41). In FIG. 10, since the nodes 1024 and 1025 detect the failure of the link 1034 based on the OSC signal and switch to the backup link 1044, only the nodes 1024 and 1025 notify the centralized management apparatus 1011 of the failure according to the criteria of FIG. Send a signal.

  After receiving the failure notification signal, the centralized management apparatus 1011 determines the new backup path 1062 and sets the nodes 1023 and 1026 to switch to the new backup path 1062 when a failure occurs in the link 1044 (S42 to S47). ). The process up to this point is the same as in the fifth embodiment.

  Next, an operation when failure 2 occurs in the link 1044 in a state where failure 1 is not recovered in FIG. 10 will be described. For example, when a failure 2 occurs in the link 1044, each node through which the new backup path 1061 passes detects the failure, but only the nodes 1024 and 1025 identify the failure location as the link 1044 by the OSC signal. Since the nodes 1024 and 1025 are not set to switch to the spare resource in response to the failure of the link 1044, the failure notification signal is sent to the centralized management device 1011 and other devices in accordance with the criteria shown in FIG. To (adjacent node). Here, the node 1024 sends a failure notification signal to the centralized management apparatus 1011 and the node 1023, and the node 1025 sends a failure notification signal to the centralized management apparatus 1011 and the node 1026. Since the subsequent operation is the same as that of the fifth embodiment, description thereof is omitted here.

  The operation of each node of the communication system according to the sixth embodiment will be described with reference to FIG. 11, FIG. 12, and FIG. 11 is a configuration example of the node, FIG. 12 is a flowchart of the operation of the node, and FIG. 14 is a determination criterion of the failure notification signal transmission destination in the failure notification destination determination unit.

  As shown in FIG. 11, after a failure has occurred in the adjacent link of the node, until the failure notification signal reaches the node control unit 1112 (S121), it is the same as in the fifth embodiment. Receiving the failure notification signal, the node control unit 1112 checks whether only the failure notification signal based on the OSC signal is set to switch to the spare resource in the own node for the notified failure (S122). When the setting has been made (S122 / Yes), the node control unit 1112 instructs the resource switching unit 1113 to switch to the spare resource, and in response to this, the resource switching unit 1113 switches to the spare resource (S1221). ). Thereafter, the node control unit 1112 sends a failure notification signal to the failure notification destination determination unit 1115 to request determination of the failure notification destination.

  Upon receiving the failure notification destination determination request, the failure notification destination determination unit 1115 determines the failure notification destination based on FIG. 14 (S123), and sends the failure notification destination to the node control unit 1112. This criterion is characterized in that it is checked whether the failure notification signal is based on the OSC signal or not.

  Receiving the failure notification destination, the node control unit 1112 sends a failure notification signal to the notification destination (S124). Further, since the operation when the node control unit 1112 receives a failure notification signal from another node (S121) is the same as that of the fifth embodiment, the description thereof is omitted here.

  Further, the operation of the centralized management apparatus of the communication system according to the sixth embodiment is the same as that described in the first and fourth embodiments, so that the description thereof is omitted here.

  As described above, in the sixth embodiment, when each node detects a network failure or receives a failure notification signal from another node, the determination criterion in which the content of the failure notification signal is set in advance (FIG. 14). By determining the notification destination device of the failure notification signal, it is possible to prevent an excessive number of failure notification signals from being exchanged between the devices.

[Seventh Embodiment]
The configuration and operation of the centralized management apparatus and the node in each of the above-described embodiments can be executed by either hardware alone, software alone, or a combined hardware and software configuration.

  When executing processing by software, a program recording the processing sequence described in each of the above embodiments may be installed in a network management device or a memory in a node and executed.

  For example, the program can be recorded in advance on a hard disk or a ROM (Read Only Memory) as a recording medium. Alternatively, the program is temporarily or permanently stored on a removable recording medium such as a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto optical) disc, a DVD (Digital Versatile Disc), a magnetic disc, or a semiconductor memory. It can be stored (recorded). Such a removable recording medium can be provided as so-called package software.

  The program may be wirelessly transferred from the download site to the computer in addition to being installed on the computer from the removable recording medium as described above. Alternatively, the data may be transferred to the computer by a wire via a network such as a LAN (Local Area Network) or the Internet. The computer can receive the transferred program and install it on a recording medium such as a built-in hard disk.

  As mentioned above, although each embodiment of this invention was described, it is not limited to said each embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary. For example, the above embodiments can be arbitrarily combined in configuration and operation. In addition, for example, the processing operations described in the above embodiment are not only executed in time series, but are also executed in parallel or individually as required by the processing capability of the apparatus that executes the processing. It is also possible to construct.

It is a figure explaining the communication system by the 1st, 4th embodiment of this invention. It is a figure explaining the structure of the node in the communication system by the 1st-4th embodiment of this invention. It is a figure explaining the structure of the centralized management apparatus in the communication system by the 1st-6th embodiment of this invention. It is a flowchart explaining operation | movement of the 1st-6th communication system of this invention. It is a flowchart explaining operation | movement of the node in the communication system by the 1st-4th embodiment of this invention. It is a sequence diagram explaining operation | movement of the centralized management apparatus by the 1st-6th embodiment of this invention. It is a figure explaining the structure of the communication system by the 2nd Embodiment of this invention. It is a figure explaining the structure of the communication system by the 3rd Embodiment of this invention. In the communication system by the 4th Embodiment of this invention, it is the table | surface which showed the list | wrist of the endpoint node designated until the centralized management apparatus 111 of FIG. 1 finds the path | route 162, and the result of the path | route calculation with respect to each. It is a figure explaining the structure of the communication system by the 5th, 6th embodiment of this invention. It is a figure explaining the structure of the node in the communication system by the 5th, 6th embodiment of this invention. It is a flowchart explaining operation | movement of the node in the 5th, 6th embodiment of this invention. It is a figure which shows the rule which a failure notification destination determination part uses for determination of a failure notification signal transmission destination in the node of the 5th Embodiment of this invention. It is a figure which shows the rule which a failure notification destination determination part uses for determination of a failure notification signal transmission destination in the node of the 6th Embodiment of this invention. It is a network comprised by the node of patent document 1, and is a figure which shows the example of the network structure which can prevent the reliability fall of the existing path | pass by the method of patent document 1. FIG. FIG. 3 is a diagram illustrating an example of a network configuration that is configured by nodes described in Patent Literature 1 and that cannot prevent a decrease in reliability of an existing path by the method of Patent Literature 1;

Explanation of symbols

111 Centralized management devices 121-128 Network nodes 131-135 1: 1 working links 141-145 redundancy links 151-135 working links 131-135, free links 161-153, non-redundant links 161 working paths 162 working Path of new protection path of path 161 21 Failure detection unit 22 Node control unit 23 Resource switching unit 24 Failure notification signal transmission / reception unit 30 Failure notification signal reception unit 31 Failure notification analysis unit 32 Backup path creation determination unit 33 Route calculation unit 34 Link information Database 35 Existing path information database 711 Centralized management devices 721 to 728 Network nodes 731 to 735 1: 1 working links having redundancy of 1: 1 741 to 745 Backup links of working links 731 to 735 751 to 753 Free spaces without redundancy Link 761 working path 762 new protection path route of working path 761 811 centralized management device 821 to 828 network node 831 to 835 working link 841 to 845 having redundancy of 1: 1, protection link 851 to working link 831 to 835 respectively -853 Free link without redundancy 861 Working path 862 New backup path route of working path 861 Centralized management device 1021-10212 Network nodes 1031-1037 1: 1 working links 1041-1047 respectively working Backup links of links 1031 to 1037 1051 to 1056 Links without redundancy 1061 Active path 1062 New backup path route of active path 1061 1063 New backup path route of path 1062 1111 Fault detection unit 1111 Node control unit 1113 Resource switching unit 1114 Failure notification signal transmission / reception unit 1115 Failure notification destination determination unit 1511 to 1518 Network nodes 1521 to 1525 1: 1 working links having redundancy of 1531 to 1535 spare links of working links 1521 to 1525, respectively 1541 to 1543 Redundant link without redundancy 1551 Working path 1552 Route of new protection path of working path 1551 1611 to 1618 Network nodes 1621 to 1625 Redundant working links 1631 to 1635 Protection links of working links 1621 to 1625, respectively 1641 to 1643 Redundant links without redundancy 1651 Working path 1652 Possible paths 1661 to 166 in the route calculation of the new backup path of the working path 1651 2 Section where there is no free resource when setting up a backup path on route 1652

Claims (24)

A communication system for setting a backup resource for a communication line whose redundancy has been lost due to a network failure,
Identifying a failure location based on a failure notification signal sent from a node that has detected the network failure, setting a predetermined node on the path of a working communication line as an endpoint candidate according to the failure location, the endpoint A communication system comprising: a network management device that determines the spare resource based on a result of route calculation performed based on a candidate. The network management device includes:
2. The communication system according to claim 1, wherein two nodes existing at a position sandwiching the failure location on the path of the working communication line are set as the end point candidates. The network management device includes:
3. The communication system according to claim 1, wherein a node other than the node that has detected the network failure is set as the end point candidate among nodes on the path of the active communication line. The network management device includes:
If the route calculation fails, another node located in a direction away from the failure location with respect to the node set as the end point candidate among the nodes on the path of the active communication line is set as a new end point candidate. The communication system according to claim 1, wherein the communication system is set as follows. The network management device includes:
When the route calculation fails, a node that is adjacent to the node set as the end point candidate in the direction away from the failure location is set as the new end point candidate among the nodes on the path of the active communication line. The communication system according to claim 4, wherein the communication system is set. The node is
When the own node detects a network failure and sends a failure detection signal, or when a failure notification signal is received from another node, the source of the failure notification signal is switched to the spare resource in the own node. 6. The communication system according to claim 1, wherein a notification destination of the failure notification signal is determined according to a setting state of the communication system. A network management device for managing communication lines on a network,
A failure location identifying means for identifying a failure location based on a failure notification signal sent from a node that has detected a network failure;
Endpoint candidate setting means for setting a predetermined node on the path of the working communication line as an endpoint candidate according to the failure location;
Endpoint spare resource determining means for determining the spare resource based on the result of route calculation performed based on the endpoint candidate;
A network management apparatus comprising: The endpoint candidate setting means includes:
8. The network management apparatus according to claim 7, wherein two nodes existing at a position sandwiching the failure location on the path of the active communication line are set as the end point candidates. The endpoint candidate setting means includes:
9. The network management apparatus according to claim 7, wherein a node other than the node that has detected the network failure is set as the end point candidate among nodes on the path of the working communication line. The endpoint candidate setting means includes:
If the route calculation fails, another node located in a direction away from the failure location with respect to the node set as the end point candidate among the nodes on the path of the active communication line is set as a new end point candidate. The network management device according to claim 7, wherein the network management device is set as follows. The endpoint candidate setting means includes:
When the route calculation fails, a node that is adjacent to the node set as the end point candidate in a direction away from the failure location is set as the new end point candidate among the nodes on the path of the active communication line. The network management device according to claim 10, wherein the network management device is set. A network node arranged on the network,
When the local node detects a network fault and sends a fault detection signal, or when a fault notification signal is received from another node, the source of the fault notification signal and switching to a spare resource at the own node A network node, comprising: a notification destination determination unit that determines a notification destination of the failure notification signal according to a setting status. A communication system control method for setting a backup resource for a communication line whose redundancy has been lost due to a network failure,
The network management device identifies a failure location based on a failure notification signal sent from the node that has detected the network failure, and sets a predetermined node on the working communication line route as an endpoint candidate according to the failure location A communication system control method, comprising: setting and determining the spare resource based on a result of route calculation performed based on the end point candidate. The network management device includes:
14. The communication system control method according to claim 13, wherein two nodes existing at a position sandwiching the failure location on the route of the active communication line are set as the end point candidates. The network management device includes:
The communication system control method according to claim 13 or 14, wherein a node other than the node that has detected the network failure is set as the end point candidate among nodes on the path of the active communication line. The network management device includes:
If the route calculation fails, another node located in a direction away from the failure location with respect to the node set as the end point candidate among the nodes on the path of the active communication line is set as a new end point candidate. The communication system control method according to claim 13, wherein the control method is set as follows. The network management device includes:
When the route calculation fails, a node that is adjacent to the node set as the end point candidate in the direction away from the failure location is set as the new end point candidate among the nodes on the path of the active communication line. 17. The communication system control method according to claim 16, wherein the communication system control method is set. The node is
When the own node detects a network failure and sends a failure detection signal, or when a failure notification signal is received from another node, the source of the failure notification signal is switched to the spare resource in the own node. The communication system control method according to any one of claims 13 to 17, wherein a notification destination of the failure notification signal is determined according to a setting state of the communication system. A program for setting a backup resource for a communication line whose redundancy has been lost due to a network failure,
A failure location identification process for identifying a failure location based on a failure notification signal sent from a node that has detected a network failure;
Endpoint candidate setting processing for setting a predetermined node on the path of the working communication line as an endpoint candidate according to the failure location;
Endpoint spare resource determination processing for determining the spare resource based on a result of route calculation performed based on the endpoint candidate;
A program that causes a computer to execute. The endpoint candidate setting process includes:
20. The program according to claim 19, wherein the end point candidate is a process of setting two nodes existing at a position sandwiching the failure location on the path of the active communication line. The endpoint candidate setting process includes:
21. The program according to claim 19 or 20, wherein the end point candidate is a process of setting a node other than the node that has detected the network failure among nodes on the path of the active communication line. The endpoint candidate setting process includes:
If the route calculation fails, another node located in a direction away from the failure location with respect to the node set as the end point candidate among the nodes on the path of the active communication line is set as a new end point candidate. The program according to any one of claims 19 to 21, wherein the program is set as The endpoint candidate setting process includes:
When the route calculation fails, a node that is adjacent to the node set as the end point candidate in the direction away from the failure location is set as the new end point candidate among the nodes on the path of the active communication line. The program according to claim 22, wherein the program is a setting process.   When the local node detects a network fault and sends a fault detection signal, or when a fault notification signal is received from another node, the source of the fault notification signal and switching to a spare resource at the own node A program for causing a computer to execute notification destination determination processing for determining a notification destination of the failure notification signal according to a setting state.

Images