From: Blaine Williams (williams.blaine@gmail.com)
Date: Fri Jun 15 2007 - 10:36:10 ART
Antonio,
You just touched on the solution. Bidir is the only way to accomplish
this task. Any implementation of PIM-SM (even with no ip pim
dm-fallback) would have (S,G) entries from the source of every
multicast stream to the RP. You only avoid (S,G) entries from the
souce of each stream to the last hop router of each stream.
Bidir PIM solves this problem by allowing traffic to be sent up the
(*,G) route towards the RP as well as down it. If a multicast packet
is received on the interface in the Incoming Interface List, it is
sent out all of the interfaces in the Outgoing Interface List towards
the multicast receivers. If a multicast packet is received on an
interface in the Outgoing Interface List, it is sent out the inteface
in the Incoming Interface List towards the RP.
Blaine W.
On 6/15/07, Antonio Soares <amsoares@netcabo.pt> wrote:
> Hello group,
>
> Any takers to this ?
>
> I understand that with PIM-BIDIR no (S,G) entries are created. But when the
> RP becomes unavailable, i assume that PIM will fallback from SM to DM. Maybe
> not, if all the interfaces are configured as PIM-SM only. So i see the the
> combinations that follow in order to avoid any (S,G) entries:
>
> - PIM-BIDIR + all PIM interfaces configured in SM only.
>
> - PIM-SM + interfaces configured in SM-DM + no ip pim dm-fallback
>
> The command "ip pim spt-threshold infinity" does not resolve the problem in
> the path from the RP upstream to the Source. At least one router will have
> an (S,G) entry.
>
>
>
> Thanks,
> Antonio
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Antonio Soares
> Sent: sexta-feira, 15 de Junho de 2007 1:24
> To: ccielab@groupstudy.com
> Subject: Avoiding (S,G) Entries
>
> Hello group,
>
> I have some problems with the task wording when it calls to avoid (S,G)
> entries in the Mcast Routing Table.
>
> I see 3 options and i would like to have your inputs regarding the different
> behaviours we get with each command:
>
> - ip pim bidir-enable and ip pim rp-address x.x.x.x bidir
>
> - no ip pim dm-fallback
>
> - ip pim spt-threshold infinity
>
>
> Thanks,
> Antonio
>
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