Hi Samir, I would like to clarify what you are describing as the multicast source because from what I'm reading things don't quite seem to align with my understanding:
Whatever device is being used to ping the multicast group is the multicast source Whatever device has joined a particular multicast group is the multicast receiver (or client as you termed it) When you ping a multicast receiver from a multicast source, while the ping going to the receiver will be multicast, the ping response to the source will be unicast The multicast receiver does not see the RP or MSDP peer as the source of the multicast traffic (though the RP/MSDP peer may have the multicast traffic initially delivered to it via a tunnel) When a multicast source tries to ping a multicast group, the RP which is acting as a MSDP Peer will advertise to its other MSDP peer about this new multicast source enabling the multicast tree to be built. The fundamental rule of RPF checks needing to be successful still applies here. So if you haven't redistributed BGP into IGP, or don't have BGP enabled on all routers in the AS or have some other means to advertise reachability outside of the local AS problems may occur. Cheers, Adam On Mon, Sep 26, 2011 at 9:48 PM, Samir Idris <[email protected]> wrote: > Hello, > > A basic question on the operation of MSDP in regards to the packet flow > from > a client in one AS to the multicast-source in another AS. > > R1 - R2 (RP) - R3 ----- R4 - R5 - R6 (RP) > > R1, R2 and R3 = AS X > R4, R5 and R6 = AS Y > > Lets assume I have an auto rp in AS X and auto rp in AS Y. They both have > reachability and can form msdp peering, perfect up till this point. > > The client in AS X tries pinging the multicast-source in AS Y: My > understanding so FAR is that the client sends the packet to the RP and then > the RP should send the packet to the multicast-source so that when the > multicast-source responds back it knows the where to send the packet back > to > i.e. the RP in AS X. > > However when i ping from the RP in AS X, I see the multicast-source > replying > back to it (it has the route back to the initiators IP) ... when i ping > from > some other router in AS X, the multicast-source doesn't reply back. > Investigating it I found out that the multicast-source has no idea where > this new initiator is. > > If it is not the RP of AS X that multicast-source sees the packet from then > in this case I will have to redistribute igp into bgp, in other words > without route-maps and stuff at the point of redistribution I will be > basically advertising my internal network to another AS in this case AS Y. > Is this the right way? What am I missing? Is there any way that the > multicast-source sees the packet coming from the source IP of AS X's RP > when > pinging from R1? > > -- > Samir Idris > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
