From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Sat Oct 07 2006 - 19:06:58 ART
Hi Riaz.
Well I would think that I would depend on the IP PIM Mode you are using,
Let's assume that we are using PIM Dense Mode as the first case.
Since PIM Dense mode would flood MCast Stream to all interfaces when
neighbors Router are present (& if the RPF toward the Source is success) and
when that Traffic reaches to neighbors that haves (*,G) Entry then it would
not be necessary to know this information, but if the Neighbor is not
directly connected (or Local) then you would have problems since the RPF
would fail, also take in consideration that in the HUB Router you need a way
to forward that multicast feed if it came to the same physical interface
(Yes use tunnel, because you would have a OIL Problem).
On the other side if are using PIM Sparse, and if you have a Source located
in that unicast not reachable Network Segment by the Routing Protocol
(assuming that the DR is the same F router in that Network Segment), then
you would have problems, since the Register Message would arrive at the RP,
but the RP would not know how to reach that Message when sending the
Register Stop, or to send the S,G Join towards the source. So I would think
that the information would arrive to Groups known by the RP, but The PIM SM
Switchover would fail, and the S,G Joins would not have a Path to the Source
(Yes all kinds of Problems) also take in consideration that All routers
perform RFC Check to see if the current Mcast Data Stream Camed from the
Correct Interface (That is how the Routers in the Path knows that they have
joined the correct Source Stree, in that Jumbo Mumbo combination of Shared
and Source trees created by PIM Sparse Mode (but yet it works)
IMO, I would redistribute the information to the current IGP to have global
reachability
Just my 2 cents
Victor.-
-----Mensaje original-----
De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de riaz
shams
Enviado el: Sabado, 07 de Octubre de 2006 05:28 p.m.
Para: ccielab@groupstudy.com
Asunto: multicast question.
hi group ,
can anyone pls clear my doubt on this,
three routers, R1 R2 and R3 connected on frame -relay hub and spoke style.
R2 is hub. OSPF is running as a routing protocol and R3's one interface is
not part of ospf.
i have given igmp-join group on ethernet's interface of R3 and multicast is
running on all three routers.
now if i ping from R1 to that multicast address , it sometime pings and
sometimes not.
i have also checked RPFs and RP mappings.
do i need to bring that interface's subnet in routing domain for multicast
address to be pingable ?
Tia
riaz.
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