JP2013207636A - Method and device for controlling path switching in network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for controlling path switching, by which the path switching can be performed at high speed with a transmission-path-dependent characteristic considered.SOLUTION: A path switching control device in a network to which a plurality of nodes (N1-N10) are connected via transmission paths includes: a path dispersion value memory (102) that stores the characteristic values of transmission paths between the nodes; and a path selection control unit (103) that, when switching a path running from a transmission end node (N1) to a reception end node (N10), selects a switching destination path by using the characteristic values of paths that are associated with the switching.

Description

  The present invention relates to a communication network management technique, and more particularly to a path switching control method and apparatus.

  With the recent increase in network traffic, the necessity of constructing a mesh network with wavelength division multiplexing (WDM) transmission is increasing. In general, in a WDM transmission system, it is necessary to set an optical receiver in consideration of the characteristics of individual transmission paths as the transmission speed increases. This is because signal conduction cannot be achieved without considering the characteristics of the transmission line. As a characteristic of such a transmission line to be considered, there is chromatic dispersion. It is known that signal conduction cannot be achieved unless an optimum dispersion value is set in the optical receiver by chromatic dispersion compensation. A WDM system considering wavelength dispersion is disclosed in, for example, Patent Document 1 and Patent Document 2.

  As described above, chromatic dispersion compensation is essential for signal conduction in WDM transmission. However, since chromatic dispersion is a characteristic that depends on the transmission path, for example, when the transmission path is switched due to a failure or the like, the dispersion compensation process must be performed again on the new transmission path. However, in general, the dispersion compensation process requires minutes. For this reason, when the path is switched, the time required for dispersion compensation is lost as it is. Usually, since path switching for a transmission path failure requires a short time of about several tens of ms to 1 sec, it is practically impossible to perform arbitrary path switching. Therefore, a transmission path switching in a WDM network is generally a fixed path, and a predetermined path is used when a transmission path failure occurs. If the switching path is fixed, dispersion compensation processing can be performed in advance, and switching can be performed immediately without performing dispersion compensation processing when a transmission path failure occurs.

  In the case of a ring network, the device that becomes the receiving end at the time of switching is self-explanatory for the path through which the main signal is conducted, so it is possible to switch the chromatic dispersion value by holding the chromatic dispersion value of the planned switching path in advance. Is possible.

JP 2006-033248 A Japanese Patent Laid-Open No. 2003-060577

  However, in the mesh network, the planned switching path cannot be specified. Therefore, when switching occurs inside the mesh network, the device serving as the receiving end cannot determine the path through which the main signal is conducted. For this reason, it is necessary to execute dispersion compensation processing again at the receiving end, and there is a problem that the signal cannot be conducted during the dispersion compensation processing time. In this way, in a network in which the planned switching path is not fixed or changes, path switching considering transmission path dependent characteristics cannot be executed at high speed.

  Accordingly, an object of the present invention is to provide a path switching control method and apparatus capable of performing path switching considering transmission path dependence characteristics at high speed.

  A path switching control apparatus according to the present invention is a path switching control apparatus in a network in which a plurality of nodes are connected by a transmission path, and includes storage means for storing characteristic values of transmission paths between nodes, and a transmission end node to a reception end. And a route selection control unit that selects a switching destination route using a characteristic value of a route related to the switching when the route to the node is switched.

  A path switching control method according to the present invention is a path switching control method in a network in which a plurality of nodes are connected by a transmission path, wherein the characteristic value of each inter-node transmission path is stored in the storage means, and the transmission end node to the reception end When switching the route to the node, the switching destination route is selected using the characteristic value of the route related to the switching.

  According to the present invention, in a network in which a planned switching path is not fixed or changes, path switching considering transmission path dependent characteristics can be performed at high speed.

FIG. 1 is a block diagram showing an example of a communication network system including a path switching control device according to an embodiment of the present invention. FIG. 2 is a network diagram schematically showing an example of route switching in FIG. FIG. 3 is a flowchart showing the operation of each node in FIG. FIG. 4 is a flowchart showing the registration operation of the upper network apparatus in FIG. FIG. 5 is a flowchart showing the path switching operation of the upper network apparatus in FIG.

  According to the embodiment of the present invention, a chromatic dispersion value that is a characteristic value unique to a transmission line such as an optical fiber through which a signal is conducted is managed by a control plane (upper network management device). When a transmission line failure occurs and the transmission line needs to be switched, the switching point is determined by referring to the transmission line characteristic value managed by the control plane (upper network management device). It is possible to select the optimum route at. At this time, the switching can be executed without dispersion compensation processing by notifying the receiving end node of the dispersion value after switching. Furthermore, by switching to a transmission line that exhibits the characteristic closest to the characteristic value of the transmission line before switching (that is, by switching so that the influence is minimized), it is possible to avoid signal interruptions due to dispersion value switching.

  More specifically, the distributed values of all routes in the network are measured before the operation is started, and are managed by the control plane (upper network management device). In addition, a dispersion value measurement signal (a signal with a different wavelength is used as the main signal) is connected between each node, the dispersion value during normal operation is always measured, and the measured dispersion value is controlled by the control plane (upper network management). If the notification is sent to the device, the control plane can always update the dispersion value to be managed, and the transmission path can be switched in accordance with the actual network state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a WDM mesh network as an example.

1. One Embodiment As shown in FIG. 1, consider a network in which nodes N1-N10 are connected by a transmission line. Each node is a device constituting a WDM network, and has a wavelength Add / Drop function, an optical amplification function, a wavelength cross-connect function, and the like.

  The host network management device 100 is a device that manages the entire network belonging to the control plane, and has a function of collecting and managing information on the nodes N1 to N10 in the network. As an example, the upper network management apparatus 100 includes a management control unit 101 that controls the operation of the entire management apparatus, a path distributed value memory 102 that stores internode transmission paths in the network and their distributed values in association with each other, and switching And a route selection control unit 103 that selects an optimum route when it occurs.

  In FIG. 1, the numerical value described in each inter-node transmission path represents a dispersion compensation value in the transmission path. For example, the dispersion value on the transmission line between the nodes N3 and N6 is “10”, and the dispersion value on the transmission line between the nodes N6 and N8 is “20”. These distributed values are measured at each node and notified to the upper network management apparatus 100.

  The management control unit 101 of the higher-level network management apparatus 100 registers the distributed value notified from each node in the path distributed value memory 102 and configures the distributed value map of the entire network. When path switching becomes necessary due to a transmission path failure or the like, the path selection control unit 103 selects a path with a variance value closest to the current value among candidate paths while referring to the path variance value memory 102, Notify the node to change the route. At that time, the distributed value after the path switching is also notified to the receiving end node.

  For example, in FIG. 1, when a client signal having the node N1 as a transmission end and the node N10 as a reception end is transmitted via the nodes N2, N3, N6, N8 and N9, as shown in FIG. And a failure in the transmission path between N8 and N8 (such as an optical fiber break). In this case, the node N8 notifies the failure occurrence information to the higher-level network device 100. As a detour route candidate of the route in which the failure has occurred (node N2-N3-N6-N8), there are a route of node N2-N5-N8 and a route of node N2-N4-N7-N8. The route selection control unit 103 refers to the route variance value memory 102, compares the variance values of the two detour route candidates, and selects the candidate closest to the failure occurrence variance value of the nodes N2-N3-N6-N8. To do. Therefore, in this case, the route of the nodes N2-N4-N7-N8 is determined as a bypass route. By notifying the receiving end N10 of the dispersion value of the determined route, the route can be switched without dispersion compensation processing.

2. Node Operation Before the start of operation, each of the nodes N1 to N10 measures a variance value between nodes using a variance value measurement signal, and notifies the higher level network apparatus 100 of the measurement value. During normal operation (in a state where no switching has occurred), the variance value may vary depending on the operation. Therefore, the variance value is measured and notified as shown in FIG.

  In FIG. 3, each node periodically transmits a dispersion value measurement signal to measure a dispersion value between the nodes (operation 201). It is determined whether or not there is a change in the measured variance value (operation 202). If there is a change in the variance value (operation 202; YES), the higher-level network management apparatus 100 is notified of the variance value information (operation 203). ).

3. 3. Operation of upper network management apparatus 3.1) Registration operation As shown in FIG. 4, when the management control unit 101 of the upper network management apparatus 100 receives the distributed value information from the node (operation 301), the path distributed value memory 102 is stored. A search is performed to determine whether or not the transmission path of the variance value information is a registered path (operation 302). If registered (operation 302; YES), the received distributed value information is overwritten in the route distributed value memory 102 as an updated value (operation 303). If the transmission path is not registered in the path variance value memory 102 (operation 302; NO), it is registered in the path variance value memory 102 as a new path (operation 304).

3.2) Path switching operation When transmission path failure occurrence information is received from a node (operation 401), the management control unit 101 refers to the path variance value memory 102 and routes that bypass the fault location and the variance values in the routes Is obtained (operation 402). Subsequently, the route selection control unit 103 determines the optimum detour route by comparing the variance values between the candidate routes (operation 403). As a selection criterion, a candidate route having a variance value as close as possible to the variance value of the failure occurrence route is selected. For example, in the case where a failure occurs in the transmission path between the nodes N6 and N8 in FIG. 2, the detour path (node N2- N4-N7-N8) is selected.

  When the detour route is determined, the management control unit 101 notifies each node of the route change (operation 404), and notifies the node serving as the receiving end of the distributed value after the route switching (operation 405). Thus, the node that has received the notification of the route change changes the route as notified, and the node that becomes the receiving end changes the setting to the notified distributed value. In this way, signals can be transmitted and received through the detour route between the transmitting end node and the receiving end node.

4). Effect As described above, according to the present embodiment, when a node that detects a transmission path failure notifies the control plane (upper network management device) of the fact, the control plane (upper network management device) that has received the notification A route whose variance value is closest to the current value is determined as a switching route among routes that bypass the failure location. Each node is notified of the route change, and the node that is the receiving end is notified of the distributed value after switching. The node that becomes the receiving end that has received the dispersion value switches the dispersion value in the apparatus to the received value, so that the path can be switched without performing dispersion compensation processing again. Furthermore, since a route with a close variance value is selected before and after the occurrence of a failure, it is possible to avoid a main signal loss due to variance value switching.

  As described above, according to the present invention, it is not necessary to secure a fixed path for switching when a transmission path failure occurs, and an optimum detour path can be selected when a failure occurs. In addition, the redispersion compensation processing at the node that becomes the receiving end when switching occurs is not necessary. Furthermore, since the redispersion compensation process is not required, the time until the main signal conduction after switching can be shortened.

  According to the present invention, even in the case of route switching such as trouble transfer, the route can be switched without re-dispersion compensation processing by notifying the node that is the receiving end of the dispersion value after switching. In the case of trouble transfer, since the dispersion value between the nodes is managed by the higher-level network management device, it is possible to select a switching route that has the least influence on the main signal.

  Further, the present invention can obtain the same effect even if transmission path characteristics other than the chromatic dispersion value are used. For example, the present invention can be applied to the gain efficiency of an optical amplifier, and it is possible to eliminate the need to recalculate the transmission path characteristics by switching paths. In addition, the present invention is not limited in network configuration, and can be implemented in any network configuration.

  The present invention is applicable to a network including transmission apparatuses using wavelength division multiplexing transmission.

100 Host Network Management Device 101 Management Control Unit 102 Path Distribution Value Memory 103 Path Selection Control Unit N1-N10 Node

Claims (9)

A path switching control device in a network in which a plurality of nodes are connected by a transmission path,
Storage means for storing characteristic values of transmission paths between nodes;
A path selection control means for selecting a switching destination path using a characteristic value of a path related to the switching when switching a path from the transmitting end node to the receiving end node;
A path switching control device comprising:   The path switching control device according to claim 1, wherein a characteristic value of the switching destination path is notified to the receiving end node.   The route switching control device according to claim 1, wherein the route selection control unit selects a route having a characteristic value closest to the characteristic value of the route as a switching destination.   The path switching control device according to claim 1, wherein the network is a mesh network of a wavelength division multiplexing transmission system. A path switching control method in a network in which a plurality of nodes are connected by a transmission path,
Store the characteristic value of each inter-node transmission path in the storage means,
When switching the route from the transmitting end node to the receiving end node, the switching destination route is selected using the characteristic value of the route related to the switching.
A path switching control method characterized by the above.   6. The path switching control method according to claim 5, wherein a characteristic value of the switching destination path is notified to the receiving end node.   The route switching control method according to claim 5 or 6, wherein a route showing a characteristic value closest to the characteristic value of the route is selected as a switching destination.   The path switching control method according to claim 5, wherein the network is a mesh network of a wavelength division multiplexing transmission system. A network management device for managing a network in which a plurality of nodes are connected by a transmission path,
Storage means for storing characteristic values of transmission paths between nodes;
A path selection control means for selecting a switching destination path using a characteristic value of a path related to the switching when switching a path from the transmitting end node to the receiving end node;
A network management apparatus comprising:

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