/mcpshow ip pim rp map PIM Group-to-RP Mappings
Group(s) 224.0.0.0/4 RP 10.1.1.1 (?), v2v1 Info source: 10.1.1.1 (?), elected via Auto-RP Uptime: 00:21:26, expires: 00:02:24 router2#
The RP for 224.1.1.1 is 10.1.1.1. Check if this is one of the interfaces of router2:
<#root> router2# show ip interface brief
Interface IP-Address OK? Method Status Protocol Ethernet0/0 10.1.1.2 YES NVRAM up up Ethernet1/0 10.2.1.1 YES NVRAM up up Ethernet2/0 unassigned YES NVRAM administratively down down router2#
Since router2 is not an RP, it must not have received this RP-Join packet. Check why the downstream router sent the Join to router2, while it must not:
<#root> router3# show ip pim rp map PIM Group-to-RP Mappings
Group(s) 224.0.0.0/4 RP 10.1.1.1 (?), v2v1 Info source: 10.1.1.1 (?), elected via Auto-RP Uptime: 00:24:30, expires: 00:02:16 Group(s): 224.0.0.0/4, Static-Override RP: 10.2.1.1 (?) router3#
As you see, router3 has statically configured RP information and points to router2, which is incorrect. This explains why router3 sends RP-Join to router2. Possible Fixes Either make router2 the RP for the group 224.1.1.1 or change the configuration on router3 so it refers to the correct RP address.