Re: Bidirectional PIM scenario

From: Jonathan Greenwood II (gwood83@gmail.com)
Date: Thu Jan 15 2009 - 03:18:38 ARST

I don't think bidirectional PIM is based upon the topology but more so what
are you trying to achieve like whether or not to allow certain
routers/switches to be able to install S,G entries from a particular source
or to prevent unicast PIM register messages being sent to a router/switch
from a particular source. In regards to your statement in relation to PIM
SM this is direct from the DocCD

"For packets that are forwarded downstream from the RP toward receivers,
there are no fundamental differences between bidir-PIM and PIM-SM. Bidir-PIM
deviates substantially from PIM-SM for traffic that is passed from sources
upstream toward the RP. "

http://cisco.com/en/US/docs/ios/ipmulti/configuration/guide/imc_basic_cfg_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1054929

HTH

Jonathan

On Wed, Jan 14, 2009 at 2:50 PM, Hobbs <deadheadblues@gmail.com> wrote:

> hello,
>
> I am trying to learn more about bidirectional PIM but no matter what type
> of
> lab topology I come up with, multicast works anyway. Anyone know a good
> topology I can configure where multicast would fail unless you enable bidir
> pim?
>
> The topology I use right now has this (copied from doccd config guide)
>
> R1 (Receiver) ---- R2 ---- R3 (RP) ----- R4 ----- R5 ----- R6 (Sender)
> |
> |
> R7----- R8 (Receiver)
>
> If you cant see the topology correctly R4 is where the split to R7 happens.
> R1 and R8 are receivers
> R3 is the RP
> R6 is the sender.
> All interfaces are PIM-SM, Autorp listener everywhere
>
> Even with this setup, R4 will accept (S,G) incoming from R5, forward it to
> R3, then accept (*,G) on that same interface from R3 to forward it out
> R7/R8. I always thought this could not happen. I have disabled the
> SPT-switchover (ip pim spt-threshold infinity).
>
> R4#sho ip mroute 225.0.0.1 | begin \(\*
> (*, 225.0.0.1), 00:12:10/00:03:08, RP 3.3.3.3, flags: S
> Incoming interface: Serial1/0, RPF nbr 192.168.34.3
> Outgoing interface list:
> Serial1/1, Forward/Sparse, 00:12:10/00:03:08
>
> (192.168.56.6, 225.0.0.1), 00:00:22/00:03:21, flags: T
> Incoming interface: Serial1/2, RPF nbr 192.168.45.5
> Outgoing interface list:
> Serial1/0, Forward/Sparse, 00:00:22/00:03:09, A
> Serial1/1, Forward/Sparse, 00:00:22/00:03:08
>
> On R4:
>
> s1/0 = R3
> s1/1 = R7
> s1/2 = R5
>
> thanks,
>
>
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