Method and apparatus for selecting between multiple equal cost paths
First Claim
1. A method of selecting between multiple equal cost paths in a communication network, the method comprising:
- determining a set of equal cost paths between a pair of nodes on a communication network, each path comprising at least one link;
constructing a first link identifier for each link of the at least one link on each of the equal cost paths, each of the first link identifiers being created by concatenating ordered node identifiers of nodes that connect to the link on the communication network;
constructing a first path identifier for each of the equal cost paths, each of the first path identifiers being created by concatenating first link identifiers of the at least one link forming the respective path through the communication network;
ranking the first path identifiers in a path-independent manner to select a first set of diverse paths through the communication network;
constructing a second link identifier for each link of the at least one link on the equal cost paths, each of the second link identifiers being created by concatenating a node identifier of one of the nodes that connect to the each link on the communication network with an inverted node identifier of other of the nodes that connect to the each link on the communication network, the node identifiers being concatenated to form the respective second link identifiers in the same order as determined when constructing the first link identifiers;
constructing a second path identifier for each of the equal cost paths, each of the second path identifiers being created by concatenating second link identifiers of the at least one link forming the respective equal cost path through the communication network; and
ranking the second path identifiers in a path-independent manner to select a second set of diverse paths through the communication network.
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Abstract
Each equal cost path is assigned a path ID created by concatenating an ordered set of link IDs which form the path through the network. The link IDs are created from the node IDs on either set of the link. The link IDs are sorted from lowest to highest to facilitate ranking of the paths. The low and high ranked paths are selected from this ranked list as the first set of diverse paths through the network. Each of the link IDs on each of the paths is then renamed, for example by inverting either all of the high node IDs or low node IDs. After re-naming the links, new path IDs are created by concatenating an ordered set of renamed link IDs. The paths are then re-ranked and the low and high re-ranked paths are selected from this re-ranked list as the second set of diverse paths.
182 Citations
23 Claims
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1. A method of selecting between multiple equal cost paths in a communication network, the method comprising:
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determining a set of equal cost paths between a pair of nodes on a communication network, each path comprising at least one link; constructing a first link identifier for each link of the at least one link on each of the equal cost paths, each of the first link identifiers being created by concatenating ordered node identifiers of nodes that connect to the link on the communication network; constructing a first path identifier for each of the equal cost paths, each of the first path identifiers being created by concatenating first link identifiers of the at least one link forming the respective path through the communication network; ranking the first path identifiers in a path-independent manner to select a first set of diverse paths through the communication network; constructing a second link identifier for each link of the at least one link on the equal cost paths, each of the second link identifiers being created by concatenating a node identifier of one of the nodes that connect to the each link on the communication network with an inverted node identifier of other of the nodes that connect to the each link on the communication network, the node identifiers being concatenated to form the respective second link identifiers in the same order as determined when constructing the first link identifiers; constructing a second path identifier for each of the equal cost paths, each of the second path identifiers being created by concatenating second link identifiers of the at least one link forming the respective equal cost path through the communication network; and ranking the second path identifiers in a path-independent manner to select a second set of diverse paths through the communication network. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a communication network, the communication network comprising a plurality of nodes interconnected by links, the method comprising, at each node:
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implementing a link state routing protocol process to enable the node to exchange network configuration information with other nodes on the communication network and to calculate paths through the communication network; and for each set of equal cost paths between a pair of nodes on the communication network, each path comprising at least one link; constructing a first link identifier for each link of the at least one link on each of the equal cost paths, each of the first link identifiers being created by concatenating ordered node identifiers of nodes that connect to the link on the communication network; constructing a first path identifier for each of the equal cost paths, each of the first path identifiers being created by concatenating the first link identifiers of the at least one link forming the respective equal cost path through the communication network; ranking the first path identifiers in a path-independent manner to select a first set of diverse paths through the communication network; constructing a second link identifier for each link of the at least one link on the equal cost paths, each of the second link identifiers being created by concatenating a node identifier of one of the nodes that connect to the each link on the communication network with an inverted node identifier of other of the nodes that connect to the each link on the communication network, the node identifiers being concatenated in the same order as determined when constructing the first link identifiers; constructing a second path identifier for each of the equal cost paths, each of the second path identifiers being created by concatenating the second link identifiers of the at least one link forming the respective equal cost path through the communication network; and ranking the second path identifiers in a path-independent manner to select a second set of diverse paths through the communication network. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification