Patent ID: 9647926
Date: 2017-05-09
CPC Classifications: H04L

Claim:
1. A method executed by a network device to identify multi-homed prefixes in an intermediate system-intermediate system (IS-IS) area or IS-IS domain during shortest path first (SPF) computation for use in a loop free alternate (LFA) computation, where a prefix is a range of Internet Protocol addresses, the method comprising the steps of: selecting a next node in a shortest path tree (SPT) representing a topology of the IS-IS area or IS-IS domain; determining a set of prefixes associated with selected node in the SPT; selecting a next prefix from the set of prefixes of the selected node; checking whether the selected prefix exists in the local RIB associated with another node of a same level in the SPT that is different from the selected node; marking the selected prefix as a multi-homed prefix where the selected prefix existed in the local RIB associated with the other node, where the marking is recorded in the local RIB or a multi-homed prefix tracking data structure of the network device; checking whether all prefixes associated with the selected node are processed; checking whether all nodes in the SPT have been processed; and downloading the local RIB to a global RIB.