Re: msdp sa message

Nice info! Thanks

I am rebuilding my lab, and plan on labbing this up as well.

Rock on team, and thanks!!!!!!

Andrew Lee Lissitz (all)

On Fri, Jan 28, 2011 at 6:24 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> Good link indeed.
> All, one thing that helped to grasp multicast is to understand that
> there is no synchronization between source and destination.
> What that means is that "it has to work" in two different scenarios:
>
> -source starts first (sending, i.e. active source w/o destinations)
> -destination starts first (i.e. no active source at that time)
>
> Most examples I've seen assume one of the cases, and that is missleading
> sometimes.
> MSDP is no exception. That is why SAs get sent every 60 seconds while
> there is an active source. SA caching helps reducing join latency too.
>
> My .02
> -Carlos
>
> ALL From_NJ @ 28/01/2011 18:56 -0300 dixit:
>
> Team!!!
>>
>> Thanks Dan. Yep, the doc also mentioned that ... looks pretty handy
>> indeed
>> ...
>>
>> Brian - that link is awesome!!! Early in the document it helps me learn
>> and
>> filled some holes in my understanding! In fact the first few bullet list
>> items are very helpful to me.
>>
>> I also want to thank Tyson who labbed this as well!!!
>>
>> Thanks team,
>>
>> You all rock! I hope you all have a great weekend!
>>
>> Andrew
>>
>>
>>
>> On Fri, Jan 28, 2011 at 2:01 PM, Dan Shechter <danshtr_at_gmail.com> wrote:
>>
>> A tip: use "*ip msdp mesh-group"* command to overcome MSDP RPF problems
>>> in
>>> the lab.
>>>
>>> So nice of Jeff Doyle to mention that... :)
>>>
>>>
>>> HTH,
>>> Dan #13685 (RS/Sec/SP)
>>> The CCIE troubleshooting blog: http://dans-net.com
>>>
>>>
>>> On Fri, Jan 28, 2011 at 8:55 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:
>>>
>>> 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
>>>>
>>>>
>>>> Blogs and organic groups at http://www.ccie.net
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>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Andrew Lee Lissitz
>>>> all.from.nj_at_gmail.com<mailto:all.from.nj_at_gmail.com>
>>>>
>>>>
>>>> Blogs and organic groups at http://www.ccie.net
>>>>
>>>> _______________________________________________________________________
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>>>> http://www.groupstudy.com/list/CCIELab.html
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>>>
>>> Blogs and organic groups at http://www.ccie.net
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>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>

-- 
Andrew Lee Lissitz
all.from.nj_at_gmail.com
Blogs and organic groups at http://www.ccie.net