RE: msdp sa message

Whether the SA is accepted or not uses a more complicated logic than a normal
RPF check. It is RFC defined, and you can see more info about it here:
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gt_msdp.html

HTH,

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com
Internetwork Expert, Inc.
http://www.INE.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705

From: ALL From_NJ [mailto:all.from.nj_at_gmail.com]
Sent: Thursday, January 27, 2011 9:33 PM
To: abderrahim sadki
Cc: Brian McGahan; abderrahim sadki; ccielab_at_groupstudy.com; Narbik
Kocharians
Subject: Re: msdp sa message

Hello and good evening wonderful team,

A quick question for clarification on the RPF check that each MSDP peer would
do in a larger network w/ multiple autonomous systems (or a CCIE scenario)
...

Lets say you have two separate AS, and YOU ARE NOT sharing all routes between.
There is no default or summary routes between the two AS.

MSDP peers share info and each learns about another source in the other AS.
Here is my confusion:

1) In this scenario, won't you have a RPF failure or will each MSDP peer
simply drop the advertisement since they do not know anything about the others
source?

2) If using BGP to overcome any RPF failures or to solve this scenario, do you
only have to advertise the source address from the other AS?

I believe you have to advertise each sending source address ...

3) Does each RP/MSDP peer become the next hop then in the BGP table?

Sorry team ... my lab is not up and running yet.

I am also interested in hearing others comments, gotchas, and good advice.
Many TIA team and have a good night,

Andrew

On Thu, Jan 27, 2011 at 3:36 PM, abderrahim sadki
<sadkia_at_gmail.com<mailto:sadkia_at_gmail.com>> wrote:
Thank you Narbik and Brian. It is clear.

Abderrahim

On 01/26/2011 01:23 AM, Brian McGahan wrote:
The only action taken is that the (S,G) entry is installed in the SA cache.
MSDP is just used to tell the RPs where the sources are, it doesn't have
anything to do with building the tree. PIM is still used for the formation of
the tree, which occurs once the RP receives a (*,G) PIM join for a group that
is in the SA cache. The (S,G) entry will then be installed in the multicast
routing table, and the (S,G) tree joined back to the source.

HTH,

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com

-----Original Message-----
From: nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>
[mailto:nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>] On Behalf Of
abderrahim sadki
Sent: Tuesday, January 25, 2011 2:24 PM
To: ccielab_at_groupstudy.com<mailto:ccielab_at_groupstudy.com>
Cc: sadkia_at_gmail.com<mailto:sadkia_at_gmail.com>
Subject: msdp sa message

Hi all,

After going through the multicast configuration guide I am a bit confused:

When the MSDP peer receives the SA message from the other domain, does he
send
a (S,G) join message back to the RP? or does it decapsulate it and forwards
it
to the receivers.

Thanks,
Abderrahim

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Received on Fri Jan 28 2011 - 12:55:52 ART