IP Multicast Overview
Auto-RP automates the distribution of group-to-RP mappings in a network supporting PIM-SM. Auto-RP supports the use of multiple RPs within a network to serve different group ranges and allows configurations of redundant RPs for reliability purposes. Auto-RP allows only one RP to be active at once. Auto-RP can be used as the distribution mechanism to advertise the Anycast RP addresses previously discussed The automatic distribution of group-to-RP mappings simplifies configuration and guarantees consistency.
The Auto-RP mechanism operates using two basic components, the candidate RPs and the RP mapping agents.
Candidate RPs advertise their willingness to be an RP via “RP-announcement” messages. These messages are periodically sent to a reserved well-known group 18.104.22.168 (CISCO-RP-ANNOUNCE).
RP mapping agents join group 22.214.171.124 and map the RPs to the associated groups. The RP mapping agents advertise the authoritative RP-mappings to another well-known group address 126.96.36.199 (CISCO-RP-DISCOVERY). All PIM routers join 188.8.131.52 and store the RP-mappings in their private cache.
Cisco AVVID Network Infrastructure IP Multicast Design