JP5168499B2 - Communication network system and high-reliability method of path - Google Patents

Description

  The present invention relates to a communication network system and a path reliability method.

  With an increase in data communication traffic, it is important to improve reliability in a communication network, especially a transport network that is a core part of the communication network. In the transport network, a path for traffic transmission is set between nodes that transmit and receive data. If a failure or the like occurs in a node or link through which this path passes and communication becomes impossible, data cannot be transmitted between the transmitting and receiving nodes. Thereafter, communication cannot be performed until the transmission / reception nodes are connected by another communicable path.

  The reliability of the transport network can be expressed by using the time taken from when communication between transmitting and receiving nodes becomes impossible to when communication is possible again, that is, the path failure recovery time. In other words, the shorter the path failure recovery time, the higher the network reliability.

  The path failure recovery method is divided into two types: a protection method and a restoration method. In the protection method, an alternative path that does not intersect with the working path is set in advance for the working path used for normal traffic transmission. On the other hand, in the restoration method, an alternative path is set after a failure occurs in the working path.

  In the protection method, even if the working path becomes unusable, it is possible to recover from a failure only by switching the used path from the working path to the alternative path. However, since the alternate path is always maintained even when there is no failure in the working path, the utilization efficiency of the network resource (link bandwidth) is deteriorated. Therefore, 1 + 1 protection and M: N protection are properly used according to the level of reliability required for the path.

  In 1 + 1 protection, the same traffic can be sent to both the working path and the alternative path. Therefore, even if any of the paths becomes incapable of communication, the communication is recovered only by switching the path for receiving the signal at the receiving node. This makes it possible to recover from a failure very quickly. However, since two paths are secured for one communication, the network resource utilization efficiency is halved.

  On the other hand, in M: N protection, M alternative paths are shared by N active paths (M and N are natural numbers such that M ≦ N). When the working path becomes incapable of communication, each transmitting / receiving node performs switching processing from the working path to one of M alternative paths. Since the switching process is performed in the transmission / reception node, the failure recovery time becomes longer than that of 1 + 1 protection. However, since the same alternate path can be shared by a plurality of working paths, the utilization efficiency of network resources is better than that of 1 + 1 protection. Further, when the working path is communicable, traffic that may be low in reliability can flow on the alternative path, so that the utilization efficiency of network resources can be further increased.

  In the restoration method, after the working path becomes unusable, switching processing is performed not only at the transmission / reception node but also at the relay node in order to set an alternative path. For this reason, failure recovery takes as much time as setting one path. If the alternative path route is not determined in advance, the failure recovery is further delayed by the route calculation. If the necessary bandwidth is not available, the setting of the alternative path fails and the setting of the alternative path must be performed again. On the other hand, the use efficiency of the network resources is higher than the protection method because the alternative path is not set. Further, since the network resources for the alternative path can be shared by a plurality of working paths having different transmission / reception node pairs, the utilization efficiency of the network resources can be further increased.

  It is against a single failure (single node or link failure) in the network that 100% failure recovery can be guaranteed in the protection scheme. That is, when two or more failures occur in the network at the same time, it is not guaranteed that communication between the transmitting and receiving nodes is possible. In order to guarantee 100% recovery from a k-fault by the protection method, k alternate paths are required for one working path (k is an integer of 2 or more in this column). . In this case, although it is possible to recover from k-heavy faults, it will take the same time as 1 + 1 protection method or M: N protection method, and the network resource utilization efficiency will be reduced to about 1 / k. To do.

  On the other hand, although the restoration method can cope with an arbitrary failure, if there is not enough free bandwidth, the failure cannot always be recovered. Some network users, such as governments and banks, require extremely high reliability for paths, and there is a need for a mechanism that can quickly and reliably recover a single path even if multiple failures occur in the network. Yes. However, a method for a network operator providing a path to efficiently provide such a path in terms of cost has not been shown at present.

  For example, Japanese Patent Laid-Open No. 2006-135686 (see Patent Document 1) discloses a path recovery method for a plurality of link failures based on a protection method. However, the plurality of link failures in Patent Document 1 is limited to a case where a failure occurs in a pipeline in which a plurality of links are accommodated, and the plurality of links accommodated therein become unusable at the same time. Is done.

  Japanese Patent Laying-Open No. 2006-340058 (see Patent Document 2) shows a method in which a protection system can be expanded and a path can be surely recovered for a k-fault. However, according to this method, k alternative paths are required for one path. This is very inefficient from the viewpoint of network resource utilization efficiency.

  Japanese Patent Application Laid-Open No. 2007-49336 (refer to Patent Document 3) discloses a path recovery method for multiple failures by combining a protection method and a restoration method. However, this method does not necessarily guarantee that a path can be recovered 100% in a time equivalent to that of the protection method for a k-fault.

  Japanese Patent No. 3900194 (see Patent Document 4) discloses a method of recovering a path from multiple failures using a restoration method. However, the multiple failure here is limited only to the multiple link failure, and the multiple node failure is not supported.

JP 2006-135686 A JP 2006-340058 A JP 2007-49336 A Japanese Patent No. 3900194

  As described above, several failure recovery systems and methods for multiple failures have already been shown. However, there is a problem that there is no system or method that combines the three features of being able to recover from a failure as fast as the protection method, recovering a path even for multiple failures, and having good network resource utilization efficiency. there were.

  An object of the present invention is to provide a communication network system and a path high-reliability method that solves the above-described problem that can combine the three characteristics.

  A communication network system according to a first aspect of the present invention includes a path database and a path switching unit. The path database stores grouping data for grouping one working path and another working path protected by an alternative path into the same group. When a failure occurs in one working path, the path switching unit refers to the grouped data and performs switching to another working path belonging to the same group as the one working path.

  The path reliability improvement method according to the second aspect of the present invention includes: setting a first working path; setting a second working path; protecting; grouping; Switching. In setting the first working path, the first working path is set from the transmitting node to the receiving node in the communication network. In setting the second working path, the second working path is set from the transmitting node to the receiving node. In protection, the second working path is protected by an alternative path. In grouping, the first working path and the second working path are grouped into the same group. In switching, when a failure occurs in the first working path, the path is switched to the alternative path of the second working path belonging to the same group as the first working path.

  According to the present invention, a communication network system that can combine the three characteristics of being able to recover from a failure as quickly as the protection method, recovering a path even for multiple failures, and using network resources efficiently, It becomes possible to provide a highly reliable method.

Basic configuration diagram of the network assumed in the first embodiment Explanation of configuration of nodes in the first embodiment Explanatory drawing of the path setup request message received by the sending node Explanatory drawing of the path setup request message created by the sending node Illustration of path deletion request message A diagram showing an example of a path before a failure occurs Diagram explaining the state of the topology database before failure Diagram explaining the state of the path database before failure The figure which shows the example of the path after the failure recovery with 1 + 1 protection The figure explaining the switching process which node N6 performs by failure recovery by 1 + 1 protection Diagram showing an example of a path after multiple failure recovery The figure explaining the switching process which the node N6 performs by recovery from multiple failures Diagram explaining the state of the topology database when multiple failures occur Diagram explaining the state of the path database when multiple failures occur Diagram explaining the state of the path database after multiple failure recovery Explanatory diagram of failure recovery message Explanation of configuration of nodes in the second embodiment

  Embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a basic configuration diagram of a network assumed in the first embodiment. The network in FIG. 1 includes nodes N1 to N6 and links L1 to L8. In the figure, nodes N1 to N6 indicated by squares have a switching function and a function for setting a path between nodes. The links L1 to L8 indicated by solid lines connect the nodes, and are media for transmitting data, such as copper wires and optical fibers.

  FIG. 2 is a diagram for explaining the configuration of the node. Each of the nodes N1 to N6 illustrated in FIG. 1 has a configuration similar to that illustrated in FIG. In FIG. 2, one node includes a communication unit M1, a route calculation unit M2, a path setting unit M3, a path switching unit M4, a topology database M5, a path database M6, a switch M7, and an input signal monitor M8. To M11 and a failure analysis unit M100. In FIG. 2, the number of inputs and outputs of the switch M7 is 4 for convenience of explanation. The actual number of inputs / outputs depends on the scale of the switch M7.

  In the figure, the communication unit M1 has a function for communicating with a communication unit in another node. The route calculation unit M2 calculates the route of the path based on the topology information stored in the topology database M5. The path setting unit M3 operates the switch M7 via the path switching unit M4 to set a path and manage path information stored in the path database M6. The path switching unit M4 performs a switching operation of the switch M7. Input signal monitors M8 to M11 monitor signals input to the switch M7. The failure analysis unit M100 analyzes the failure based on monitoring by the input signal monitors M8 to M11.

  The topology database M5 stores topology information related to the network connection form. Specifically, information such as an output node, an input node, an output port at the output node, an input port at the input node, a free bandwidth, and a link state is stored for each of the links L1 to L8. The path database M6 stores path information related to each path. Specifically, for each current path or alternative path, the transmission node, the reception node, the input port, the output port, the bandwidth used, the presence / absence of protection, and the type of protection when protection is applied, are secured. Stores information such as alternative paths. Such information can be notified by a path setting request message transmitted / received between nodes.

《Explanation of operation to set path to network》
The communication unit M1 mediates message transmission / reception between the route calculation unit M2 or the path setting unit M3 and the communication unit in another node. First, an operation when the communication unit M1 receives a path setting request message from another node will be described. The communication unit M1 transfers the path setting request message to the path setting unit M3.

  [1-1. When the transmission node of the path specified in the received path setting request message is its own node] FIG. 3 is an explanatory diagram of the path setting request message. This path setting request message is received by the transmission node of the newly set path. As shown in the figure, the path setting request message S1 includes information on the transmission node, the reception node, and the path bandwidth.

  The path setting unit M3 requests the path calculation unit M2 to calculate the path of the path. The route calculation unit M2 requested to calculate the route from the path setting unit M3 refers to the free bandwidth information of the link stored in the topology database M5 and calculates the route of the path. The result is returned to the path setting unit M3. Upon receiving the path route calculation result from the route calculation unit M2, the path setting unit M3 registers information on the newly set path in the path database M6.

  Further, the path setting unit M3 requests the path switching unit M4 to switch the switch M7. The path switching unit M4 switches the switch M7 based on the request. Further, when the switching process is completed, this is notified to the path setting unit M3. The path setting unit M3 notifies the route calculation unit M2 that the switch M7 has been switched. Further, a path setting request message is created for the next hop node in the newly set path, and the path setting request message is passed to the communication unit M1.

  FIG. 4 shows an explanatory diagram of the path setting request message. This path setting request message is generated by the transmission node of the newly set path. As shown in the figure, the path setting request message S2 includes a path identification code, a transmission node, a reception node, a path bandwidth, and a link through which the path passes (in FIG. 4, a set of a node and an output port). Information about a pair of a node and an input port or may be expressed by a link identifier or the like). The communication unit M1 that receives the path setting request message from the path setting unit M3 transmits the path setting request message to the next-hop node.

  [1-2. When the transmission node of the path specified in the received path setting request message is not its own node] The path setting unit M3 registers information on the newly set path in the path database M6. Also, the switching is requested to the path switching unit M4. The path switching unit M4 performs a switching process. Further, when the switching process is completed, this is notified to the path setting unit M3. The path setting unit M3 notifies the route calculation unit M2 that the switch M7 has been switched. Further, a path setting request message as shown in FIG. 4 is created for the next hop node in the newly set path, and the path setting request message is passed to the communication unit M1. The communication unit M1 that receives the path setting request message from the path setting unit M3 transmits the path setting request message to the next-hop node.

  [1-3. When the receiving node of the path specified in the received path setting request message is its own node] The path setting unit M3 registers information on the newly set path in the path database M6. Also, the switching is requested to the path switching unit M4. The path switching unit M4 performs a switching process. Further, when the switching process is completed, this is notified to the path setting unit M3. The path setting unit M3 notifies the route calculation unit M2 that the switch M7 has been switched.

  The path calculation unit M2, which is notified by the path setting unit M3 that the switching process has been completed, updates information related to its own node in the topology database M5. Further, in order to notify the other nodes of the update of the topology information, a topology update message including the updated information is created and passed to the communication unit M1. The communication unit M1 that receives the topology update message from the route calculation unit M2 transmits the topology update message to the destination node.

  In the destination node, when the communication unit M1 in the destination node receives the topology update message, it transfers it to the route calculation unit M2. The route calculation unit M2 updates the topology database M5 based on the topology update message.

<Description of operation to delete a path from the network>
Next, an operation when the communication unit M1 receives a path deletion request message from another node will be described. The communication unit M1 transfers the path deletion request message to the path setting unit M3. FIG. 5 shows an explanatory diagram of the path deletion request message. As shown in the figure, the path deletion request message S3 includes information for specifying a path to be deleted, such as a path identification code.

  [2-1. When the receiving node of the path specified in the received path deletion request message is not its own node] The path setting unit M3 requests the path switching unit M4 to perform switching. The path switching unit M4 performs a switching process. Further, when the switching process is completed, this is notified to the path setting unit M3. The path setting unit M3 notifies the route calculation unit M2 that the switch M7 has been switched. In addition, the path information is deleted from the path database M6. Further, a path deletion request message similar to that in FIG. 5 is created for the next-hop node in the path to be deleted, and the path deletion request message is passed to the communication unit M1. The communication unit M1 that receives the path deletion request message from the path setting unit M3 transmits a path deletion request message to the next-hop node.

  [2-2. When the receiving node of the path specified in the received path deletion request message is its own node] The path setting unit M3 requests the path switching unit M4 to perform switching. The path switching unit M4 performs a switching process. Further, when the switching process is completed, this is notified to the path setting unit M3. The path setting unit M3 notifies the route calculation unit M2 that the switch M7 has been switched. In addition, the path information is deleted from the path database M6.

<< Operation example of the entire network: Explanation during normal operation >>
FIG. 6 shows a state where two pairs of working path and alternative path are set from the node N1 to the node N6 in the network having the same configuration as that in FIG. In FIG. 6, the working paths P1 and P2 are indicated by thick solid arrows, and these alternative paths B1 and B2 are indicated by dashed arrows. The working path P1 is a path from the node N1 to the node N6 via the node N2. The working path P2 is a path from the node N1 through the node N5 to the node N6. The alternative path B1 of the working path P1 is a path from the node N1 to the node N6 via the node N3. The alternate path B2 of the working path P2 is a path from the node N1 to the node N6 via the node N4.

  In the situation where the paths P1, P2, B1, and B2 shown in FIG. 6 are set, the topology database M5 in each of the nodes N1 to N6 stores topology information related to the network connection form as shown in FIG. . FIG. 7 is an explanatory diagram showing information held in the topology database M5 in a table format. However, in the example of FIG. 7, it is assumed that the bandwidth of each link L1 to L8 is C and the bandwidth of each path P1, P2, B1, B2 is c0. The free bandwidth field in FIG. 7 is described by subtraction of the link bandwidth and the path bandwidth.

  Referring to the table T1 shown in FIG. 7, the link L1 is normally operated from the output port # 1 of the output node N1 to the input port # 1 of the input node N2, the free bandwidth is C-c0. I understand that. It can be seen that the link L2 is operating normally from the output port # 2 of the output node N1 to the input port # 1 of the input node N3, the free bandwidth being C-c0. The same applies to the other links. For example, the link L8 operates from the output port # 2 of the output node N5 to the input port # 4 of the input node N6, the free bandwidth is C-c0, and operates normally. I understand that.

  On the other hand, path information regarding paths as shown in FIG. 8 is stored in the path database M6 in each of the nodes N1 to N6. FIG. 8 is an explanatory diagram showing information of the path database M6 in a table format. Referring to the table T2 shown in FIG. 8, the path P1 is a path from the transmission node N1 to the reception node N6, and passes through the output port # 1 of the node N1 and the output port # 2 of the node N2. It can be seen that the bandwidth of c0 is occupied, the path B1 is secured as a spare alternative path, and that it is operating normally. Further, the path B1 is a path from the transmission node N1 to the reception node N6, passes through the output port # 2 of the node N1, and the output port # 2 of the node N3, and occupies a bandwidth of c0. It can be seen that there is no spare alternative path, and that it is operating normally. Note that the hyphen “-” in the table T2 in FIG. 8 means a blank.

  Referring to the protection form column in FIG. 8, it can be seen that the path P1 and the path P2 are set to 1 + 1 protection. Referring also to the protection path column, the path P1 is protected by the protection form of 1 + 1 protection by the alternative path B1, and the path P2 is protected by the protection form of 1 + 1 protection by the alternative path B2. I understand that.

  Referring to the group column in FIG. 8, it can be seen that two sets of paths P1, B1 and paths P2, B2 are associated as the same group G1. In this way, the first set of paths P1 and B1 are set as 1 + 1 protection, the second set of paths P2 and B2 are also set as 1 + 1 protection, and the paths of the paths P1 and B1 are respectively paths. When the path does not intersect with any of the routes P2 and B2, the path setting unit M3 combines two sets of the paths P1 and B1 and the paths P2 and B2 into one group. If they intersect, the path setting unit M3 divides the two sets of the paths P1 and B1 and the paths P2 and B2 into different groups.

  In the network connection form shown in FIG. 6, the node N6 having the same configuration as that shown in FIG. 2 receives four input signals, input 1 to input 4. As apparent from FIG. 7, the input 1 at the node N6 is an input from the working path P1 passing through the node N2, and the input 2 is an input from the alternative path B1 passing through the node N3. Is an input from the working path P2 via the node N4, and the input 4 is an input from the alternative path B2 via the node N5. The node N6 outputs the data transmitted from the working path P1 (or the alternative path B1) to the output 1, and outputs the data transmitted from the working path P2 (or the alternative path B2) to the output 3.

  The path switching unit M4 in the node N6 causes the failure analysis unit M100 to analyze the input signal from the working path P1 and the input signal from the alternative path B1 monitored by the input signal monitors M8 and M9. Similarly, the failure analysis unit M100 analyzes the input signal from the working path P2 and the input signal from the alternative path B2 monitored by the input signal monitors M10 and M11. At this time, the path switching unit M4 outputs the signal from the input 1 to the output 1 and the signal from the input 3 unless the failure analysis unit M100 detects an abnormality in the input signal monitor M8 or the input signal monitor M10. The state of the switch M7 that outputs to the output 3 is maintained.

<< Operation example of the entire network: Explanation when a failure occurs on one path >>
An operation in the case where a failure occurs in the working path P1 due to an abnormality in the link L5 in the network illustrated in FIG. 6 will be described. As shown in FIG. 9, failure recovery processing is performed, and the alternative path B1 is used as an alternative to the working path P1. At this time, in the node N6, an abnormality is detected by the input signal monitor M8, and the failure analysis unit M100 notifies the abnormality to the path switching unit M4. As illustrated in FIG. 10, the path switching unit M4 switches the switch M7 so that the signal input to the input 2 is output to the output 1. Since the input 2 at the node N6 is connected to the input from the alternative path B1, the alternative path B1 is used instead of the working path P1 where the failure has occurred by switching the switch M7.

  When the node N6 detects that a failure has occurred in the working path P1, the topology database M5 and the path database M6 are updated in each of the nodes N1 to N6. In the topology database M5, the status column of the link L5 in an abnormal state is updated from “normal” to “abnormal”. In the path database M6, the status column of the working path P1 where the failure has occurred is updated from “normal” to “abnormal”.

  After the failure occurs, when no abnormality is detected in the input signal monitor M8 at the node N6, the path switching unit M4 switches the switch M7 so that the input 1 signal is output to the output 1, and the input 1 signal Can be returned to the original state so that is output to the output 1.

<< Operation example of the entire network: Explanation when a failure occurs on two paths >>
An operation when a failure occurs in the working path P1 and the alternative path B1 due to an abnormality in the link L5 and the link L6 in the network illustrated in FIG. 6 will be described. As shown in FIG. 11, failure recovery processing is performed, and the alternative path B2 is used as an alternative to the working path P1. When a failure occurs simultaneously in the working path P1 and the alternative path B1, the node N6 detects an abnormality in the input signal monitors M8 and M9. The failure analysis unit M100 determines from the observation status of the input signal monitors M10 and M11 that the alternate path B2 can be used as an alternate path because the working path P2 is normal.

  In the node N6, the failure analysis unit M100 transmits the failure analysis result to the path switching unit M4. The path switching unit M4 creates a failure recovery message for notifying the transmission node N1 that the failure recovery is performed using the alternative path B2, and transfers the failure recovery message to the communication unit M1. Further, as shown in FIG. 12, the switch M7 is switched so that the input from the input 4 is output to the output 1. Since the input 4 at the node N6 is connected to the input from the alternative path B2, the alternative path B2 is used instead of the working path P1 where the failure has occurred by switching the switch M7.

  In the node N6, when it is detected that a failure has occurred in the working path P1 and the alternative path B1, the topology database M5 and the path database M6 are updated. As shown in the table T3 of FIG. 13, in the topology database M5, the status columns of the link L5 and the link L6 that are in an abnormal state are updated from “normal” to “abnormal”, respectively. As shown in the table T4 of FIG. 14, in the path database M6, the status fields of the working path P1 and the alternative path B1 in which a failure has occurred are updated from “normal” to “abnormal”, respectively.

  Thereafter, switching from the working path P1 to the alternative path B2 is performed at the node N6, and when the failure recovery processing is completed, the path database M6 is updated. As shown in the table T5 of FIG. 15, in the path database M6, the protection column of the alternative path B2 is updated from the blank column to “P1”. “P1” in this protection column indicates that the alternative path B2 of the current path P2 protects the current path P1 belonging to the same group and is used as an alternative to the current path P1. Note that the topology database M5 is not updated in the table T3 of FIG.

  In the node N6, the communication unit M1 transmits the failure recovery message created by the path switching unit M4 to the transmission node N1 of the path P1. FIG. 16 is an explanatory diagram of the failure recovery message. As shown in the figure, the failure recovery message S4 includes information for specifying a path in which a failure has occurred, and information for specifying a path used as an alternative for recovering a connection through the path. Upon receiving the failure recovery message transmitted from the communication unit M1 of the node N6, the communication unit M1 of the node N1 transfers it to the path switching unit M4. The failure recovery process is also performed at the node N1, and the path switching unit M4 of the node N1 outputs the input data (input data to the working path P1) input from the input 1 to the output 4 (output to the alternative path B2). Switch M7.

  According to the first embodiment, in a communication network system, it is possible to recover k paths from k double failures at high speed, reliability, and efficiently using network resources. That is, there are k current paths protected by 1: 1 protection, and any route in a certain working path and alternate path pair does not intersect with any other path in any other working path and alternate path pair. In this case, it is possible to reuse k alternative paths between k active paths set between the same transmitting and receiving nodes.

The case where the alternative path is set by the 1 + 1 protection method has been described above in detail. The present invention can be applied to the case where an alternative path is set by the M: N protection method and the case where an alternative path is set by the restoration method. When an alternative path is set by the M: N protection method, data indicating a plurality of alternative paths may be stored in the spare path column in the path database M6. By a simple design change, the current path and alternate path pair of the 1 + 1 protection method and the current path and alternate path pair of the M: N protection method are grouped into the same group, or the current M ₁ : N ₁ protection method current A set of paths and alternative paths and a set of current paths and alternative paths of the M ₂ : N ₂ protection scheme can be grouped into the same group.

  When an alternative path is set by the restoration method, data of an alternative path that appears at the time of failure of the current path may be stored in the protection path column in the path database M6. It is possible to group the current path and alternative path pair of the protection method and the current path and alternative path pair of the restoration method, or to group a plurality of current path and alternative path pairs of the restoration method together. it can.

  In addition, according to the present invention, a current path lacking an alternative path and a current path protected by the alternative path by an arbitrary method can be grouped into the same group.

  Another embodiment for carrying out the present invention will be described with reference to the drawings. FIG. 17 is an explanatory diagram of a node configuration according to the second embodiment. Instead of the node having the configuration of FIG. 2, the node having the configuration of FIG. 17 can be applied to the network of FIG. The nodes in the second embodiment devise the connection form of the route calculation unit M2 in the first embodiment. As shown in FIG. 17, in the second embodiment, the communication unit M12, the route calculation unit M2, and the topology database M5 can be shared by a plurality of nodes in the network. The shared topology database M5 is connected to each path setting unit M3 in a plurality of shared nodes by connecting the shared communication unit M12 and the communication unit M1 in each node. This makes it possible to reduce the number of path calculation units M2 and topology databases M5 that must be deployed in the network to only one each.

N1 to N6: Nodes L1 to L8: Link M1: Communication unit M2: Path calculation unit M3: Path setting unit M4: Path switching unit M5: Topology database M6: Path database M7: Switches M8 to M11: Input signal monitor M12: Communication Unit M100: Failure analysis unit P1: Working path B1 that passes through nodes N1, N2, and N6: Alternate path P2 that passes through nodes N1, N3, and N6 P2: Working path that passes through nodes N1, N5, and N6 B2: Nodes N1 and N4 , N6 P2 alternative paths S1 to S4: Transmission / reception messages T1, T3: Tables describing the contents of the topology database T2, T4, T5: Tables describing the contents of the path database

Claims (12)

A path database for storing grouping data for grouping one working path and another working path protected by an alternative path of the 1 + 1 protection method into the same group;
In the case where the one working path is also protected by an alternate path, when the failure occurs in the one working path, the grouped data is stored when the failure occurs in the alternate path of the one working path. A communication network system comprising: a path switching unit that switches to the alternative path of the other working path belonging to the same group as the one working path.   In the communication network system according to claim 1,
  The path database is
  To group the one working path and the second working path protected by at least one of the M: N protection type alternative path or the restoration type alternative path into the same group. The grouping data of
  Communication network system. In the communication network system according to claim 1 or 2,
The path switching unit
When a failure occurs in the other working path and a failure occurs in an alternative path of the other working path, the grouping data is referred to, and the one of the ones belonging to the same group as the other working path A communication network system that switches the working path to an alternate path. In the communication network system according to any one of claims 1 to 3 ,
The path database is
When none of the one working path, the alternative path of the one working path, the other working path, and the alternative path of the other working path intersect, the one working path; A communication network system for storing grouped data for grouping the other working paths into the same group. 5. The communication network system according to claim 1 , further comprising a plurality of nodes forming the communication network, and the path switching unit for each node in the plurality of nodes. Node used in the installed system. In the node as claimed in claim 5 ,
A switch for connecting one input among a plurality of inputs inputted from a plurality of nodes in the previous hop and one output among a plurality of outputs outputted to the plurality of nodes in the next hop;
The path switching unit
A node that switches to an alternative path by switching the switch. In a node as claimed in claim 6 ,
The path switching unit
By switching the switch, when switching to an alternative path, a failure recovery message is generated for notifying other nodes of protection information data indicating which current path is protected by the switched alternative path. node. Setting a first working path from a sending node to a receiving node in a communication network;
Setting a second working path from the sending node to the receiving node;
Protecting each of the first working path and the second working path with an alternate path that protects with a 1 + 1 protection scheme ;
Grouping the first working path and the second working path into the same group;
The second working path that belongs to the same group as the first working path when a failure occurs in the alternate path that protects the first working path when the first working path fails. Switching the path to an alternative path of the path.   In the path reliability improvement method according to claim 8,
  In the grouping,
  Grouping the one working path and the second working path protected by at least one of the M: N protection type alternative path or the restoration type alternative path into the same group.
including
  Highly reliable path method. In the path reliability improvement method according to claim 8 or 9 ,
In switching the path,
The first working path that belongs to the same group as the second working path when a failure occurs in the alternative working path that protects the second working path when the second working path fails. A path reliability improvement method further comprising switching to an alternative path. In the path | route high-reliability method described in any one of Claims 8 thru | or 10 ,
In the grouping,
When none of the first working path, the alternate path protecting the first working path, the second working path, and the alternate path protecting the second working path intersect. A path reliability enhancement method comprising grouping the first working path and the second working path into the same group. A method for switching a path used in the path reliability improvement method according to any one of claims 8 to 11 , wherein one node among a plurality of nodes forming the communication network is:
Detecting that a failure has occurred in the first working path;
Switching a path to an alternative path of the second working path belonging to the same group as the first working path;
And notifying other nodes of a failure recovery message indicating which current path the switched alternate path protected.

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