Communication network, path setting method and recording medium having path setting program recorded thereon
To prevent load of route calculation from being centralized in part of units. A node calculates routes of a primary path and an alternate path and sends them to a management center. The management center checks whether SRLGs of the two routes overlap, and instructs the node to perform calculation again if the routes overlap. The management center searches for an alternate path having a route overlapping the route of the above described alternate path. When an overlapping alternate path exists, and SRLGs of a primary path corresponding to the alternate path and the above described primary path do not overlap, a link is shared in an overlapping portion of the routes of the two alternate paths.
1. A path setting method in a communication network comprising a plurality of nodes constituting a network,
wherein each of said nodes has topology information of said network, information on a risk sharing resource group, and information on a currently set path passing the node itself, and
said method comprises:
a first step in which a source node refers to said topology information of the network and said information on the risk sharing resource group to calculate routes of a first path and a second path so as not to pass the same risk sharing resource group; and
a second step in which each node on said routes receives a signal from an upstream node, refers to said information on the risk sharing resource group and said information on the currently set path passing the node itself to detect a second path having an overlapping route in a link group between the node itself and a downstream node and compare said risk sharing resource groups of said first path.
2. A path setting method in a communication network in which a communication network as set forth in claim 1 consists of a plurality of subnetworks,
wherein each of said node comprises an external routing table showing a boundary node that a route passes when a path to a destination node in another subnetwork is set, and
said method comprises:
a third step in which a first path and a second path from a source node to said boundary node are set; and
a fourth step in which a first path and a second path from said boundary node to a destination node in another subnetwork are set.
3. A recording medium storing a path setting program for controlling a node in a communication network comprising a plurality of nodes constituting a network,
wherein each of said nodes has topology information of said network, information on a risk sharing resource group, and information on a currently set path passing the node itself, and said path setting program comprises:
a first set of instructions in which a source node refers to said topology information of the network and said information on the risk sharing resource group to calculate routes of a first path and a second path so as not to pass the same risk sharing resource group; and
a second set of instructions in which each node on said routes receives a signal from an upstream node, refers to said information on the risk sharing resource group and said information on the currently set path passing the node itself to detect a second path having an overlapping route in a link group between the node itself and a downstream node and compare said risk sharing resource groups of said first path.
4. A path setting method according to claim 1 , wherein in said second set of instructions, signaling message to set said second path includes the identity information of all of the risk sharing resource groups through which said first path passes.
5. A recording medium according to claim 3 , wherein in said second set of instructions, signaling message to set said second path includes the identity information of all of the risk sharing resource groups through which said first path passes.
6. A plurality of nodes constituting a network,
each said node comprising information including: topology information of said network, information on a risk sharing resource group, and information on a currently set path passing the node itself, and when calculating a first path and a second path having different routes, said node refers to this information, and
wherein said node receives signaling message from an upstream node including the identity information of all of the risk sharing resource groups through which said first path passes to detect the second path having an overlapping route in a link group between the node itself and a downstream node and compare said risk sharing resource groups of said first path.