From: Jason Guy \(jguy\) (jguy@cisco.com)
Date: Mon Jul 09 2007 - 12:25:33 ART
Yemi,
One small correction:
It is first important to understand the operation of pim
sparse-dense-mode. This is a Cisco-specific method of configuring pim
where the router will try and use sparse mode to service a given
multicast group joined on a connected interface. If there is no RP
setup to handle this specific group, the router will fallback to
dense-mode operation for the specific group.
The "no ip pim dm-fallback" forbids the router from falling-back to
dense-mode operation for any group that is not handled by an RP.
This does not apply to the Auto-RP groups as they are always run in
dense mode.
Jason
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Salau, Yemi
> Sent: Monday, July 09, 2007 11:08 AM
> To: Amit Kohli; ccielab@groupstudy.com
> Subject: RE: Multicast- Auto RP Question
>
> I would expect the Routers not to fallback to dense mode.
>
> Ip pim auto-rp listener temporarily allow flooding via the 224.0.1.39
> and 224.0.1.40 group (someone should correct me if I'm wrong). That
is,
> it enables the routers to use dense mode (flood) only for those 2
groups
>
> no ip pim dm-fallback ensures your Routers don't flood for every other
> group other than the 2 groups (224.0.1.39 and 224.0.140)
>
> So even with no ip pim dm-fallback, your mapping agent still need to
> push out the RP information using the 224.0.1.XX group towards the
other
> pim routers. Or in other words, if you have sparse mode configured and
> no ip pim dm-fallback, the routers can still obtain RP information
from
> the MA, provided you have the ip pim auto-rp listener configured.
>
>
> Many Thanks
>
> Yemi Salau
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Amit Kohli
> Sent: Monday, July 09, 2007 3:39 PM
> To: ccielab@groupstudy.com
> Subject: Multicast- Auto RP Question
>
> Hi
>
> In multicast, if I have the below configuration
>
>
> ip pim auto-rp listener (On every Router)
> no ip pim dm-fallback (On every Router)
> ip pim send-rp-announce loopback0 scope 16
> ip pim send-rp-discovery loopback0 scope 16
> int lo0
> ip pim sparse-dense-mode
>
>
> In the above configuration all the routers will work in sparse mode
> or dense mode?
>
> Does the command " ip pim sparse-dense-mode" takes precedence over
> the command " ip pim auto-rp-listener" ?
>
> Thanks
> Amit
>
>
>
>
>
>
> ---------------------------------
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