From: Joe Chang (changjoe@earthlink.net)
Date: Sun Dec 08 2002 - 12:24:19 GMT-3
> Hi Group,
> I have some question on Multicast over NBMA. I read from Cisco
> documentation that NBMA mode is to be used in a frame relay cloud and ip
> sparse mode should be used with this. However, I also understand
> Auto-RP, requires dense mode to broadcast its RP group advertisements.
> For example below,
>
>
> R1------R2-------FR--------R3
> \
> \___ R4
>
> R1 and R2 are connected to each other with ethernet cable. R2 is the
> central hub and R3 & R4 are spokes in the frame-relay cloud. Lets say, I
> am using R1 as my Candidate-RP and Mapping Agent. According to Cisco
> documentation I must run ip pim nbma-mode & ip pim sparse mode. R1 will
> be sending out RP information to all the routers. However, in a sparse
> mode environment the routers R3 & R4 must join the group 224.0.1.40 to
> receive this information in the first place. Theoretically, should not
> work....how then does it work?
>
You're right it won't work. ip pim sparse-dense-mode must be configured on
all the routers for this topology to work. In fact whenever multicast
routers are not directly connected to the mapping agent, sparse-dense mode
is required.
.
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