Sparse-Mode with no RP

From: gladston@br.ibm.com
Date: Tue Aug 30 2005 - 12:34:50 GMT-3


Trying to check the following discussion:

http://www.groupstudy.com/archives/ccielab/200407/msg01404.html

specifically the statement:

============
The mode of the interface DOES NOT determine whether a mcast group runs in
sparse or dense mode.
============

I got this:

If a interface is configured as sparse-mode, the router does not forward
traffic out the interface if there is no RP. That was revealed by debug,
and the tests are at the end of this email.

I am concerned with the following: is it possible to forward multicast if
there is no RP and the interfaces are configured for sparse-mode?

Tests:

When the interfaces are configured for sparse-dense-mode, R2 forwards the
multicast traffic to R6 and R8 (and receives the prune from remote
router):

Aug 30 11:42:41: PIM(0): Received v2 Join/Prune on Serial0/0.28 from
148.5.28.8, to us
Aug 30 11:42:41: PIM(0): Prune-list: (148.5.235.5/32, 239.200.1.1)
Aug 30 11:42:41: PIM(0): Prune Serial0/0.28/239.200.1.1 from
(148.5.235.5/32, 239.200.1.1)
Aug 30 11:42:41: PIM(0): Received v2 Assert on Serial0/0.26 from
148.5.126.6

When the interface 0/0.28 (lead to R8) is configured for sparse-mode, the
router does not forward multicast traffic to that router:

no result from debug for R8

Version is 12.2T. Have you seen different results?



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