From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Fri Jun 15 2007 - 11:14:44 ART
Only bidirectional PIM will solve this task. The reason why is
that when the PIM DR running in sparse mode on the segment receives a
multicast packet from a server it sends a register message to the RP.
Normally this register message is an (S,G) register, which effectively
tells the RP that source "S" is sending traffic to group "G", and to
send me a sparse-mode join message back if you have any clients that
want group "G". In bidirectional mode register message are only sent as
(*,G), which potentially cuts down on the amount of entries in the
multicast routing table if you have a lot of sources that are sending
towards the same group.
HTH,
Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Antonio Soares
Sent: Friday, June 15, 2007 6:45 AM
To: ccielab@groupstudy.com
Subject: RE: Avoiding (S,G) Entries
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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