About configuring router advertisements on multiple switches with a common VLAN

Multiple routing switches transmitting RAs on the same VLAN or tunnel can provide redundancy. Typically, a host identifies the first router from which it receives an RA as the default router. The host uses any RAs received later from other routers to identify backup default routers.

While advertised prefixes can be different, the per-VLAN or per-tunnel RA policy should be the same for all routers transmitting RAs on a given VLAN. This includes the following parameters:

  • Managed-config-flag (M-bit)

  • Other-config-flag (O-bit)

  • Default router lifetime

  • Hop-limit

  • Reachable-time for neighbors

  • Retransmit time for neighbor solicitations