BETTER ALTERNATE PATHS FOR MULTI HOMED IS-IS PREFIXES

摘要

A method is executed by a network device to determine a loop free alternate (LFA) for a multi-homed prefix in an IS-IS area or IS-IS domain. The method includes selecting a next node from the IS-IS area or the IS-IS domain and selecting a next prefix for the selected node. A check is made whether the selected prefix is a multi-homed prefix (MHP). A check is made whether a shortest path first (SPF) cost of the selected node and cost to the selected prefix is equal to an SPF cost of the selected prefix, whether a next hop of selected prefix is same as next hop of selected node, and whether a LFA next hop of the selected node is better protection than a current next hop protection of the selected prefix and the LFA next hop of the selected node is then inherited for the selected prefix.

主权项

1. A method executed by a network device to determine a loop free alternate (LFA) for a multi-homed prefix in an IS-IS area or IS-IS domain, the method comprising the steps:
selecting a next node from the IS-IS area or the IS-IS domain; selecting a next prefix for the selected node; checking whether the selected prefix is a multi-homed prefix (MHP); checking whether a shortest path first (SPF) cost of the selected node and cost to the selected prefix is equal to an SPF cost of the selected prefix; checking whether a next hop of selected prefix is same as next hop of selected node; checking whether a LFA next hop of the selected node is better protection than a current next hop protection of the selected prefix; and inheriting the LFA next hop of the selected node for the selected prefix.