Path routing computation method and optical communication network applying path routing computation method

Abstract

A path routing computation method enables reduction of the memory capacity for path routing computation. The method is characterized in that a wavelength convertible subnetwork in which paths are connected in a mesh form; a first and second wavelength inconvertible subnetworks have a starting point node and an end point node, respectively, and include a plurality of nodes and connected via the wavelength convertible subnetwork, and out of the nodes constituting the first and second wavelength inconvertible subnetworks, a node has a port connected to the wavelength convertible subnetwork is defined as a border node, and the method includes the steps of: obtaining, for the first wavelength inconvertible subnetwork, a path from the starting point node to a border node in the first subnetwork; and obtaining, for the second wavelength inconvertible subnetwork, a path from the end point node to a border node in the second wavelength inconvertible subnetwork.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a figure for explaining a ROADM ring network;

FIG. 2 is a configuration example of a ROADM device constituting a ring 1 in the network shown in FIG. 1;

FIG. 3 is a network in which a ROADM ring network 100 and a WDM network 200 are connected to each other;

FIG. 4 is a figure showing a network configuration in which a network with restricted wavelengths and a network with not restricted wavelengths are connected to each other;

FIG. 5 is a figure showing a configuration example of a network of a first embodiment of the present invention;

FIG. 6 is a figure for explaining notification of a border node;

FIG. 7 is a block diagram of a configuration example of a node device;

FIG. 8 is a figure showing a configuration example of a network of a second embodiment of the present invention;

FIG. 9 is a figure showing an example of link information when a routing protocol corresponding to the embodiment of FIG. 8 is used;

FIG. 10 is a figure for explaining exchange of border port identification information;

FIG. 11 is a flowchart of a path routing computation sequence according to the present invention;

FIG. 12 is a figure showing a state of search at the lowest cost from a starting point node A to a border node;

FIG. 13 is a figure showing a state of search at the lowest cost from an end point node Z to a border node;

FIG. 14 is a figure showing a state of search for the same border node through path search from the starting point node A and from the end point node Z;

FIG. 15 is a figure showing a path obtained from FIG. 12 through FIG. 14, the path being the lowest cost path; and

FIG. 16 is a figure showing an example in which another network 200 is connected to the network configuration shown in FIG. 8, and a plurality of border nodes are used as pathways.

Claims

1. A path routing computation method in an optical communication network including a wavelength convertible subnetwork in which paths are connected in the form of a mesh, a first wavelength inconvertible subnetwork having a starting point node, and a second wavelength inconvertible subnetwork having an end point node, the first and second wavelength inconvertible subnetworks being connected via the wavelength convertible subnetwork, wherein out of the nodes constituting the first and second wavelength inconvertible subnetworks, a node having a port connected to the wavelength convertible subnetwork is defined as a border node, the path routing computation method comprising the steps of: obtaining, for the first wavelength inconvertible subnetwork, a path from the starting point node to a border node in the first subnetwork; andobtaining, for the second wavelength inconvertible subnetwork, a path from the end point node to a border node in the second wavelength inconvertible subnetwork.

2. The path routing computation method according to claim 1, wherein when the end point node is searched by the step of obtaining, for the first wavelength inconvertible subnetwork, a path from the starting point node to a border node in the first wavelength inconvertible subnetwork, the routing computation is ended.

3. The path routing computation method according to claim 1, wherein if a border node, which is searched by the step of obtaining, for the first wavelength inconvertible subnetwork, a path from the starting point node to a border node in the first wavelength inconvertible subnetwork, does not have a border node which is searched by the step of obtaining, for the second wavelength inconvertible subnetwork, a path from the end point node to a border node in the second wavelength inconvertible subnetwork, routing computation is further performed alternately for the first wavelength inconvertible subnetwork and the second wavelength inconvertible subnetwork until the same border node is searched, with the searched border nodes as original points.

4. The path routing computation method according to claim 1, wherein a path of the lowest cost in a combination of the paths searched for the first wavelength inconvertible subnetwork and the second wavelength inconvertible subnetwork is taken as a shortest-distance path to be obtained.

5. The path routing computation method according to claim 3, wherein a path of the lowest cost in a combination of the paths searched for the first wavelength inconvertible subnetwork and the second wavelength inconvertible subnetwork is taken as a shortest-distance path to be obtained.

6. The path routing computation method according to claim 4, wherein the shortest path between the starting point node and the end point node is obtained as a predetermined shortest path in advance without considering wavelength limiting conditions, and the obtained shortest path is compared with the predetermined shortest path to determine whether to perform further routing search, on the basis of a predetermined rate with respect to the predetermined shortest path.

7. The path routing computation method according to claim 5, wherein the shortest path between the starting point node and the end point node is obtained as a predetermined shortest path in advance without considering wavelength limiting conditions, and the obtained shortest path is compared with the predetermined shortest path to determine whether to perform further routing search, on the basis of a predetermined rate with respect to the predetermined shortest path.

8. An optical communication network system comprising: a wavelength convertible subnetwork in which paths are connected in the form of a mesh;a first wavelength inconvertible subnetwork including a plurality of nodes, one of which is a starting point node and transmitting signals at a fixed wavelength; anda second wavelength inconvertible subnetwork including a plurality of nodes, one of which is an end point node and transmitting signals at a fixed wavelength,wherein, out of the nodes constituting the first and second wavelength inconvertible subnetworks, a node having a port connected to the wavelength convertible subnetwork is defined as a border node, and in the starting point node, a path to a border node in the first wavelength inconvertible subnetwork and a path from the end point node in the second wavelength inconvertible subnetwork to a border node in the second wavelength inconvertible subnetwork are obtained to set a path of the lowest cost, which is obtained in a combination of the paths searched for the first wavelength inconvertible subnetwork and the second wavelength inconvertible subnetwork, as a path from the starting point node to the end point node.

9. A node device which is connected to a wavelength convertible network and which constitutes a wavelength inconvertible subnetwork, out of a plurality of node devices each of which notifies address information and link information as topology information in order to search for and set a path from a starting point node to an end point node in a subnetwork which includes the plurality of node devices, wherein the information to be notified as the topology information includes information indicating that a home node of each of the node devices is a border node.