Router R1 Failure

The following figure shows SMLT and RSMLT in Layer 3 environments.

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SMLT and RSMLT in Layer 3 environments

R3 and R4 both use R1 as their next hop to reach IP subnet A. Even though R4 sends the packets to R2, they are routed directly at R2 into subnet A. R3 sends its packets to R1 and they are also sent directly into subnet A. After R1 fails, all packets are directed to R2, with SMLT. R2 still routes for R2 and R1. After OSPF convergence, the routing tables in R3 and R4 change their next hop to R2 to reach IP subnet A. You can configure the hold-up timer (that is, for the amount of time R2 routes for R1 in a failure) for a time period greater than the routing protocol convergence, you can configure it as indefinite (that is, the members of the pair always route for each other).

Use an indefinite hold-up timer value for applications that use RSMLT at the edge instead of VRRP.