BGP Additional Paths

Hello Rodrigo

As far as R2 is concerned, it has both paths in its routing table, but advertises only one of them. However, R2 will not immediately converge if R4 goes down. The neighbor adjacency will have to be torn down which requires timers to expire before the specific next hop is considered dead. Once that happens, then BGP will reconverge placing 5.5.5.5 as the next hop for that particular route.

If the additional paths feature is not enabled, BGP must reconverge in order for R2 to realize that it must route packets via R5, which will not be immediate, but will take some time.

I hope this has been helpful!

Laz

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