Lab 8 – Microloop Avoidance

This chapter provides a refreshing break from the Topology-Independent Loop-Free Alternate (TI-LFA) scenarios, which will resume in the upcoming chapters. It is well-suited to the current topology, requiring minimal changes from the previous lab and seamlessly transitioning to the next chapter. The TI-LFA labs have thoroughly covered the calculation of backup paths and the protection of traffic during failures by rerouting it to the post-convergence backup path.

However, what happens if a network topology change causes the primary path to potentially loop?

All routers running a link-state routing protocol, such as IS-IS, populate the Link State Database (LSDB) and independently run the Shortest Path First (SPF) algorithm to create a uniform topology map. This process results in routers converging at different times. During a topology change, some routers may have an updated map while others are still processing the SPF algorithm to arrive at...