I think the catch is 'BSR' configuration in 2811 with candidate RP being Fa0/1.1. 1841 is using (*, 239.1.1.1).(*, 239.1.1.1), 00:08:12/stopped, RP 172.16.0.2, flags: SJC  Incoming interface: FastEthernet0/1, RPF nbr 172.16.0.2  Outgoing interface li...