Multicast - HSRP-aware PIM
Protocol Independent Multicast (PIM) is a multicast routing protocol. It has no inherent redundancy capabilities and its operation is completely independent of FHRP Protocols such as HSRP. As a result, IP multicast traffic is forwarded not necessarily by the same device as is elected by HSRP. The HSRP Aware PIM feature provides consistent IP multicast forwarding in a redundant network with virtual routing groups enabled.