JP3749205B2 - Multilayer path network and nodes - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a network composed of multi-layer paths, each node of the network advertises the information of the path from its own node to other nodes, each node aggregates the information of the advertised path, It is used for a network that can handle multi-layer topology information in an integrated manner. In particular, it relates to a path opening procedure.
[0002]
[Prior art]
There is GMPLS (Generalized Multi Protocol Label Switching) as a protocol technology for managing and configuring a multi-layer network. The article “Generalized Multi protocol Label Switching: An Overview of Signaling Enhancements and Recovery Technique” (pp. 144-151) in the July 2001 issue of IEEE Communications Magazine describes a multi-layer path network composed of a plurality of layers.
[0003]
The hierarchies are fiber, wavelength, time slot, and packet in order from the lower layer, and path disconnection in each layer can be performed using GMPLS signaling & routing. Further, in GMPLS, each node can handle the topology information of each layer in an integrated manner.
[0004]
In such a multi-layer path network, a virtual network is configured from lower layer paths, and upper layer paths are routed. FIG. 7 shows an example of a multipath network composed of fiber path, wavelength path, and electrical path layers. Wavelength path routing is performed on the fiber path topology to construct a virtual network (wavelength path topology) composed of wavelength paths. The electrical path is routed on the wavelength path topology.
[0005]
In such a multi-layer path network, the virtual topology can be changed by disconnecting the path at a certain layer.
[0006]
[Problems to be solved by the invention]
As described above, since the multi-layer path network can easily change the virtual topology, the network resource can be efficiently operated by changing the virtual topology according to the traffic.
[0007]
For example, since the traffic flowing through a path has decreased, it is possible to efficiently operate network resources by disconnecting the path and allocating resources used by the path to other paths.
[0008]
At this time, if the path is suddenly disconnected, the upper layer path that has flowed through the path is disconnected. In the GMPLS network, the information that the path is disconnected is flooded to each node, so that each node reroutes the upper layer path based on the new topology information. Therefore, between the time when the path is disconnected and the time when the notification reaches each node and rerouting is performed, the path of the upper layer remains disconnected and traffic is lost.
[0009]
The present invention has been made in such a background, and provides a multilayer path network, a node, a program, and a recording medium that can disconnect a path and reconfigure a virtual topology without loss of traffic. With the goal.
[0010]
[Means for Solving the Problems]
According to the present invention, a state in which a disconnection is delayed with respect to a path to be disconnected is defined as a pre-blocking state. When a node disconnects a path starting from its own node, the path is first predicted. Declare that it is blocked. Notify all nodes in the network that the path is in a pre-blocked state. The node that receives the notification knows that the path will be disconnected, so if there is an upper-layer path routed using that path that originates from its own node, the higher-layer path Detour. The starting node trying to cut the path confirms that the upper layer path passing through the path is no longer detoured, and then cuts the path. Alternatively, the starting node that is trying to cut the path cuts the path after a predetermined time has elapsed. In any case, after the path is disconnected, the disconnection is notified to all other nodes.
[0011]
That is, the first aspect of the present invention comprises a multi-layer path, means for publishing information on a path starting from the own node to other nodes, and aggregating the information on the advertised path. It is a multi-layer path network including a node provided with means for centrally handling topology information.
[0012]
Here, a feature of the present invention is that a state in which a disconnection is delayed with respect to a path scheduled to be disconnected is defined as a pre-blocking state, and the node is in a pre-blocking state where the path starting from its own node Means for notifying other nodes of the fact, and means for grasping the pre-blocking state of the path in the network and routing the upper layer path starting from the own node so as to bypass the pre-blocked path; And means for notifying other nodes that the path has actually been disconnected from the pre-blocking state.
[0013]
Further, means for grasping the status of detour processing of another node for the notification after the own node has notified the pre-blocking state, and the notification of the pre-blocking state performed by the own node in the other node by the grasping means It is desirable to provide a means for actually disconnecting the path after confirming the completion of the detour routing for the target path.
[0014]
As a result, even if the path to be cut is actually cut, a path that bypasses the cut point is already formed at that time, and the virtual topology can be reconfigured without any traffic loss.
[0015]
Alternatively, the node may be provided with means for actually disconnecting a path to be notified after a predetermined time has elapsed after the node notifies the pre-blocking state.
[0016]
According to this, although the completion of the detour routing of the other node is not completely confirmed, the actual path can be disconnected at the time when the detour routing of the other node is almost completed. The virtual topology can be reconfigured while keeping the loss low. In this configuration, it is possible to omit the process of collecting detour routing completion notifications from other nodes, and to simplify the processing procedure.
[0017]
The second aspect of the present invention is applied to a multi-layer path network composed of multi-layer paths, and includes means for publishing information on a path starting from the own node to other nodes, and information on the advertised path. This node is provided with a means for collectively handling multi-layer topology information.
[0018]
Here, the feature of the present invention is that a state in which a disconnection is delayed with respect to a path to be disconnected is defined as a pre-blocking state, and a path starting from the own node is in a pre-blocking state. Means for notifying other nodes, means for grasping the pre-blocking state of the path in the network, routing the upper layer path starting from the own node so as to bypass the path of the pre-blocking state, and pre-blocking state And a means for notifying other nodes that the path has actually been disconnected.
[0019]
Further, means for grasping the status of detour processing of another node for the notification after the own node has notified the pre-blocking state, and the notification of the pre-blocking state performed by the own node in the other node by the grasping means It is desirable to provide a means for actually disconnecting the path after confirming the completion of the detour routing for the target path.
[0020]
Alternatively, it is desirable to provide means for actually disconnecting a path that is a target of the notification after a predetermined time has elapsed after the node notifies the pre-blocking state.
[0021]
A third aspect of the present invention is a program characterized in that, when installed in an information processing apparatus, the information processing apparatus realizes a function corresponding to the node of the present invention.
[0022]
A fourth aspect of the present invention is a recording medium readable by the information processing apparatus on which the program of the present invention is recorded. By recording the program of the present invention on the recording medium of the present invention, the information processing apparatus can install the program of the present invention using this recording medium. Alternatively, the program of the present invention can be directly installed in the information processing apparatus via a network from a server holding the program of the present invention.
[0023]
Accordingly, it is possible to realize a multilayer path network and a node that can disconnect a path and reconfigure a virtual topology without loss of traffic using an information processing apparatus such as a computer apparatus.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A multilayer path network and nodes according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram of a multilayer path network according to the present embodiment. FIG. 2 is a block diagram of the node of this embodiment.
[0025]
As shown in FIG. 1, this embodiment is composed of a multi-layer path, and aggregates the information of the notified path 1 that advertises the information of the path starting from the own node to other nodes, and the information of the announced path. It is a multi-layer path network including a node including a topology information collecting unit 2 that handles multi-layer topology information in a centralized manner.
[0026]
Here, a feature of the present invention is that a state in which a path is scheduled to be disconnected is defined as a pre-blocking state, and this pre-blocking state is a virtual topology according to a change in traffic status. The pre-blocking state generation unit 3 receives a virtual topology change instruction to change the pre-blocking state, generates the pre-blocking state generation unit 3 based on the virtual topology change instruction, and the notification unit 1 has a path starting from its own node. A means for notifying other nodes of the pre-blocking state is provided. Based on the notification received by the topology information collection unit 2, the pre-blocking state of the path in the network is grasped and the path of the upper layer starting from the own node is determined. A pre-blocking location detour routing unit 4 is provided for routing so as to bypass the pre-blocked state path, and the notification unit 1 is configured so that the pre-blocking location detour routing unit 4 actually starts from the pre-blocked state. Some that were cut in the scan at which includes a means for notifying the other nodes.
[0027]
Further, the pre-blocking location detour routing unit 4 has means for grasping the status of detour processing of other nodes in response to the notification after the notification unit 1 has notified the pre-blocking state based on the notification collected by the topology information collection unit 2. And means for actually disconnecting the path after confirming the completion of the detour routing for the path to be notified of the pre-blocking state performed by the own node in the other node.
[0028]
Alternatively, the pre-blocking location detour routing unit 4 actually disconnects the path to be notified after a predetermined time has elapsed after the notification unit 1 has notified the pre-blocking state according to the instruction of the pre-blocking state generation unit 3. Means are provided.
[0029]
In the former case, since the pre-blocking location detour routing unit 4 grasps the information collected by the topology information collection unit 2 from the signal line indicated by the broken line in FIG. 2, the control accuracy is high but the processing is complicated. In the latter case, the signal line indicated by the broken line in FIG. 2 is not necessary, and a timer is provided in the pre-blocking state generation unit 3 or the pre-blocking location detour routing unit 4, and the path is triggered when the timer expires. Since the cutting can be executed, the processing can be simplified, but the accuracy of the control is lower than the former.
[0030]
The node of the present embodiment can be realized using a computer device that is an information processing device. That is, by installing in the computer device a program that realizes a function corresponding to the node of this embodiment in the computer device by installing in the computer device, the function corresponding to the node in this embodiment in the computer device. Can be realized.
[0031]
By recording the program of the present embodiment on the recording medium of the present embodiment, the computer apparatus can install the program of the present embodiment using this recording medium. Alternatively, the program of this embodiment can be directly installed on the computer device from the server holding the program of this embodiment via the network.
[0032]
Accordingly, it is possible to realize a multilayer path network and a node that can disconnect a path and reconfigure a virtual topology without loss of traffic using a computer device.
[0033]
Hereinafter, this embodiment will be described in more detail.
[0034]
A case where the wavelength path OLSP 54 connecting Area 4 and Area 5 is disconnected in the wavelength path topology of the multilayer path network shown in FIG. 1 will be described. At this time, in the electric path topology, the electric paths ELSP 35 and ELSP 36 pass through the OLSP 54. Here, if the OLSP 54 is suddenly disconnected, traffic loss occurs in the ELSP 35 and ELSP 36. For this reason, all nodes are notified that the OLSP 54 is in the pre-blocking state. The node that has received the notification avoids the OLSP 54 and performs routing of the electrical path.
[0035]
That is, the ELSP 35 changes the route from the OLSP34-OLSP54 of the current routing route to the OLSP32-OLSP21-OLSP15. Similarly, ELSP 36 changes the path from OLSP34-OLSP54-OLSP15-OLSP16 of the current routing path to OLSP32-OLSP21-OLSP16.
[0036]
FIG. 3 is an example of a path state notification packet. In GMPLS, a routing protocol called OSPF (Open Shortest Path First) is used to notify the path status. In OSPF, the link state of the path state is mounted on the packet and flooded in the network. FIG. 3 shows that the second bit of the Option field in the link state is an operation state instruction bit, and 0 is in operation and 1 is pre-blocked, so that the path pre-block state is flooded to all nodes in the network. Show that it is possible.
[0037]
FIG. 4 is a state transition diagram of a path in which the own node is not the origin node. The state where no path is set is blocked. When the operation notification packet transmitted from the origin node is received after the path is set, the state transits to operation. During operation, when the pre-blocking notification packet transmitted by the originating node is received, the state transits to pre-blocking. If a disconnection notification packet or a timeout is detected during pre-blocking, the state transits to blocking state.
[0038]
5 and 6 show a sequence when the OLSP 54 is disconnected in the configuration of FIG. In the sequence of FIG. 5, the originating node of OLSP 54 notifies the pre-blocking state of OLSP 54 to all other nodes, the originating nodes of ELSP 36 and ELSP 35 perform detouring of ELSP 36 and ELSP 35, and the detour completion notification is included in the announcement. The origin node of the OLSP 54 receives the notification, confirms that there is no ELSP passing through the OLSP 54, and then disconnects the OLSP 54. In this embodiment, the detour completion notification is described as being included in the notification, but other methods such as using a detour completion notification packet may be used.
[0039]
In the sequence of FIG. 6, after the origin node of the OLSP 54 is pre-occluded, the OLSP 54 is disconnected after waiting for a timeout without confirming the detour of the ELSP in another node. The difference between the two effects is as described above.
[0040]
【The invention's effect】
As described above, according to the present invention, when a path is disconnected in a multi-layer path network, the advance notice of disconnection is notified to all the nodes so that other nodes can bypass the upper layer path. It is possible to disconnect the path and reconfigure the virtual topology without loss of traffic.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a multilayer path network according to an embodiment.
FIG. 2 is a block configuration diagram of a node according to the present embodiment.
FIG. 3 is a configuration diagram of a path state notification packet according to the present embodiment.
FIG. 4 is a diagram illustrating path state transition according to the embodiment.
FIG. 5 is a sequence diagram at the time of path disconnection (with detour completion confirmation) according to the present embodiment.
FIG. 6 is a sequence diagram at the time of path disconnection according to the present embodiment (no confirmation of detour completion).
FIG. 7 is a diagram for explaining a multilayer path network;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Notification part 2 Topology information collection part 3 Pre-occlusion state generation part 4 Pre-occlusion part detour routing part

Claims (8)

Consists of multi-layer paths,
A means for notifying other nodes of path information originating from the own node;
In a multi-layer path network including nodes equipped with a means for centrally handling multi-layer topology information by aggregating advertised path information,
Define the state where the disconnection is delayed for the path scheduled to be disconnected as the pre-occlusion state,
The node is
Means for notifying other nodes that the path originating from the own node is in a pre-blocked state;
Means for grasping the pre-blocking state of the path in the network and routing the upper layer path starting from the own node so as to bypass the path in the pre-blocking state;
A multilayer path network comprising: means for notifying other nodes that a path has actually been disconnected from a pre-blocking state. Means for grasping the status of detour processing of other nodes for the notification after the own node has notified the pre-blocking state;
2. The apparatus according to claim 1, further comprising: means for actually disconnecting the path after confirming completion of detour routing for the path to be notified of the pre-blocking state performed by the own node in the other node by the grasping means. Multi-layer path network. The multi-layer path network according to claim 1, further comprising means for actually disconnecting a path to be notified after a predetermined time has elapsed since the self-node has notified the pre-blocking state. Applied to multi-layer path networks consisting of multi-layer paths,
A means for notifying other nodes of path information originating from the own node;
In a node equipped with a means for centrally handling multilayer topology information by aggregating advertised path information,
Define the state where the disconnection is delayed for the path scheduled to be disconnected as the pre-occlusion state,
Means for notifying other nodes that the path originating from the own node is in a pre-blocked state;
Means for grasping the pre-blocking state of the path in the network and routing the upper layer path starting from the own node so as to bypass the path in the pre-blocking state;
A node comprising means for notifying another node that a path has been actually disconnected from the pre-blocking state. Means for grasping the status of detour processing of other nodes for the notification after the own node has notified the pre-blocking state;
5. The apparatus according to claim 4, further comprising: means for actually disconnecting the path after confirming completion of detour routing for the path to be notified of the pre-blocking state performed by the own node in the other node by the means for grasping. node. The node according to claim 4, further comprising means for actually disconnecting a path to be notified after a predetermined time has elapsed after the self-node notifies the pre-blocking state. A program that, when installed in an information processing apparatus, causes the information processing apparatus to realize a function corresponding to the node according to any one of claims 4 to 6. A recording medium readable by the information processing apparatus on which the program according to claim 7 is recorded.

Images