From: Sadiq Yakasai (sadiqtanko@gmail.com)
Date: Tue Apr 15 2008 - 06:53:17 ART
Hello,
First of all, an observation about the topology that you drew out:
R1 (s1/1) is also connected to R3 (s1/3)??? or is it:
R1 (s1/1) is also connected to R3 (s1/0)??
The show ip mroute suggests so anyway (I am jst confirming cos my
analysis depends on this premise).
On R3:
(*, 239.0.0.8), 00:15:07/00:03:22, RP
4.4.4.4, flags: SF
Incoming interface: Serial1/3, RPF nbr 172.12.34.4
Outgoing interface list:
Serial1/1, Forward/Sparse, 00:14:54/00:03:22
(172.12.13.1, 239.0.0.8), 00:00:53/00:02:43, flags: FT ====>>>> see below
Incoming interface: Serial1/0, RPF nbr 0.0.0.0
Outgoing interface list:
Serial1/1, Forward/Sparse, 00:00:53/00:03:22
That flag suggests R3 has joined the SPT tree towards R1 and hence
your filtering is being by-passed. Enter the command <ip pim
spt-threshold infinity> on R3 to prevent it from joining the SPT
towards the source and the traffic would flow through the RP and you
would see the expected behaviour (or at least move closer to what you
want to see).
PS: By default Cisco routers switch over from shared distribution
trees to SPT after they receive the first packet.
Pass the CCIE in six weeks, Guaranteed!
http://www.certscience.com/CCIE
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