TI-LFA with Flex-Algo over SR MPLS

When unexpected problems arise in the network, some good plans for rerouting are essential to ensure that services keep running smoothly. Network operators use algorithm-based forwarding rules to control how backup paths are selected, guaranteeing that rerouted traffic upholds the same service objectives as the primary route. This method benefits uninterrupted connectivity applications like real‐time collaboration or distance learning. Integrating such streamlined protection schemes enables consistent performance, simplifies engineering tasks, and enhances end‐user experiences by minimizing the impact of network failures.
The TI-LFA specification ensures that the node SIDs associated with a certain Flexible Algorithm (Flex-Algo) will be safeguarded by loop-free alternates, allowing rapid convergence when a link or node fails. In addition, it demands that these "repairs" computed by those standards should only consider node SIDs or adjacent SIDs related to FlexAlgo.
In this evaluation, we performed the TI-LFA test within a network that runs FlexAlgo 128 (which prioritizes paths with lower latency). After DUT detected a link failure on the primary path, automated traffic switching occurred quite rapidly to the alternate route under the strict definitions of Flex-Algo 128. It didn't default to a standard IGP alternative when making its path decision. Our measured failover times stayed almost always under the threshold of 50 ms, fully aligned with our sub-50-ms target for highly available services.

This test has generally confirmed the applicability of TI-LFA in protecting SR-MPLS networks under FlexAlgo constraints in fast reroute settings and adapting to link failures. We can ensure multi-vendor interoperability even in advanced SR deployments with minor changes, like merging routing capability into IGP advertisements.