I have stucked on a problem with my configuration of multicast routing.
The topology is as simple as it it can be: R1 <-> R2 <-> R3 <-> R4 <-> R5 <-> R6
The links are either FR or Eth (i n my opinion it doesn't make any difference).
I launched OSPF (all links and loopbacks in area 0) and PIM sparse-dense mode (all links and loopbacks)
With Auto RP R6 is RP candidate and R5 is the mapping agent.
Everything worked great (R1 joined group 126.96.36.199 and ping from R6 was successful) until i changed the topology a little bit:
1. I blocked PIM neighbor relationship on R3 towards R2
2. I configured a GRE tunnel R1 <-> R3 (between loopbacks with pim sparse-dense and OSPF)
From there ping from R6 to the 188.8.131.52 is not successful any more.