Continuing with Multicast topics I will talk this time about Anycast RP. Anycast RP is used for RP redundancy. As I explained in my previous posts on multicast it is possible to have RP redundancy with Auto-RP by defining multiple RP servicing the same multicast groups (the RP with the highest IP will be selected as the active RP for a specific group by the MA). PIM BSR can also be used for RP redundancy and the process is the same as with Auto-RP apart from the fact that the BSR router doesn´t elect which RP is active for a specific group. In both cases the failover delay is based on the RP/BSR/MA advertisement intervals which are not fast by default (up to 60 seconds). So the whole point with Anycast RP is that the failover is based on the IGP running in the multicast domain which can be really fast (especially when using Bidirectional Forwarding Detection).
For this post I will use the same topology as the other multicast posts:
Scenario: R4 and R2 will be configured as static RPs sharing the same IP address. An MSDP session will be established between R4 and R2 in order to synchronize source IP information
RPs: R4 and R2 with IP 126.96.36.199
IGP: EIGRP AS 100
Platform/IOS: Cisco 2691/12.4(15)T11 Adv IP services
All the routers in the PIM SM topology are configured with PIM SM. For this post I will only use static RP assignment as it is the most commonly used method for group-to-RP mapping due to its deterministic nature. Auto-RP or PIM BSR could also have been used.