EXTENDED REMOTE LFA FAST REROUTE

摘要

A method is implemented by a network element or controller for determining a backup path for a fast reroute process to be utilized in response to a network event invalidating a primary path to a destination node. The method identifies at least one intermediate node that has a backup loop free alternative (LFA) path to a destination node in a network where no path meeting LFA conditions can be found for a point of local repair (PLR).

主权项

1. A method implemented by a network element for determining a backup path for a fast reroute process to be utilized in response to a network event invalidating a primary path to a destination node, where the method identifies at least one intermediate node that has a backup loop free alternative (LFA) path to a destination node in a network where no path meeting LFA conditions can be found for a point of local repair (PLR), the method comprising the steps of calculating shortest paths from the PLR to each destination node in the network using a normal topology;
calculating shortest paths from the PLR to each destination node in the network using a unit cost topology; selecting a next destination node D in the network without a calculated backup path from the PLR; determining a primary path next hop node F for the destination node D; checking whether an LFA path or remote LFA (RLFA) path exists from the PLR to the destination node D where the backup LFA path or RLFA path does not traverse the primary path next hop node F in the calculated shortest paths using the normal topology; checking whether a remote RLFA path exists from the PLR to the destination node D where the backup LFA path or RLFA path does not traverse the primary path next hop node F in the calculated shortest paths using the unit cost topology; determining an intermediate node on a shortest path that does not traverse the primary next hop node F and that meets LFA conditions; and selecting the intermediate node on the shortest path as an intermediate destination for data traffic for destination node D.