- Written by Sarah Chen
- Posted on January 12, 2022
- Updated on May 5, 2025
- 12399 Views
IS-IS flexible algorithm (FlexAlgo) provides a lightweight, simplified mechanism for performing basic traffic engineering functions within a single IS-IS area. FlexAlgo requires the cooperation of all nodes within the IS-IS area but does not require an external controller. Paths are computed by each node within the area, resulting in an MPLS switched forwarding path to nodes that are advertising a node Segment Identifier (SID) for the algorithm. The results of the path computation are placed in the colored tunnel RIB or system tunnel RIB, which simplifies route resolution.