From: Venkataramanaiah.R (vramanaiah@gmail.com)
Date: Fri Dec 02 2005 - 20:36:49 GMT-3
Hi,
I have the following FR topology..
______R2_____R4
/
R1--
\______R3_____R5 (239.5.5.5)
I have PIM Sparse mode running everywhere.. and of course with PIM nbma
mode at R1.
R2 is the RP and R1 is the MA. R5 has joined some group, Say
239.5.5.5(Will call this Grp5 henceforth).
There are two issues in this topology. Let me discuss them one by one.
1) When R5 sends PIM join to the RP (R2) via R3, the joins are sent directed
to R2 from R3. This prevents the join to become successful. We can fix this
by adding a static mroute at R3 for the RP pointing to R1. THis will let the
shared tree to be built from the RP R2 via, R1-R3 and the receiver R5. Hope
there are no other solutions for this problem.
2) When we ping the Grp5 from R4, the packets would reach the receiver for a
while. After sometime, the last hop DR (i.,e R5) tries to switchover to SPT
and this breaks the multicast flow in the FR cloud. We can probably fix this
by using SPT threshold infinity at R5. Then the traffic would flow smoothly
to R5. The main issue that i am unable to address is when we have some group
say Grp3 joined at R3 and if we ping this group from R2. In this case,
setting spt-threshold infinity at R3, does not seem to help. Since the
source is on the same network address in the FR cloud, the ping works for a
while through the shared tree via R1, but after sometime, R3 seem to be
tearing down the source tree because it thinks the source is directly
connected and it stops the mulitcast flow for a while. I am sure you guys
would have faced this issue, so I am wondering if there is any solution for
this problem..
Thank you
-Venkat
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