Re: MSDP CACHING PEER VS RPF PEER

Right, directly connected in this context means "having direct MSDP
peering session"

2011/12/23 Imran Ali <immrccie_at_gmail.com>:
> *THANKS for great info .*
>
> but how can you say msdp peer directly connected ? .
>
> IN my senario RP's are centrally located in each PIM SM domain , and are
> physically not directly connected .
>
> are you referring to logical tcp connection on port 639 ?
>
>
>
>
>
> On Fri, Dec 23, 2011 at 8:41 PM, Petr Lapukhov
> <petr_at_internetworkexpert.com>wrote:
>
>> I belive your question is "whether the SA messages in SA Response are
>> subject to peer-RPF checks" and "whether the caching peer must be on
>> RPF path toward the originating RP". The answer is no to both
>> questions, and there are two reasons:
>>
>> 1) MSDP SA request/response messages are not relayed, they are
>> exchanged on pure p2p basis between two directly connected MSDP
>> speakers (peers). Therefore, there is no need for RPF check for
>> request message - it could be sent to any caching peer. Futhermore,
>> the requesting RP does not know the originating RP address prior to
>> requesting group state. There is even no field in SA Request message
>> to encode this information :) So even if you want, you can't do an RPF
>> check - only request the cached state for a group.
>>
>> 2) MSDP SA response messages do not carry any piggy-backed multicast
>> data, unlike the SA message, so there is no need to relay that
>> information either, and hence no need to RPF check the SA Response
>> message.
>>
>> It is interesting to notice, that details on SA Request message
>> exchange did not make it to MSDP RFC, though you can find them in the
>> draft documents. The final RFC only specifies the TLV codes for
>> request/response messages.
>>
>> --
>> Petr Lapukhov, petr_at_INE.com
>> CCIE #16379 (R&S/Security/SP/Voice)
>> CCDE #20100007
>>
>> Internetwork Expert, Inc.
>> http://www.INE.com
>> Toll Free: 877-224-8987
>> Outside US: 775-826-4344
>>
>> 2011/12/23 Imran Ali <immrccie_at_gmail.com>:
>> > hI
>> >
>> > Does the caching RP in MSDP must be a peer RPF neighbor to the RP sending
>> > SA request messages ?
>> >
>> > can a non rpf peer in msdp act like a caching RP ??
>> >
>> >
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-- 
Petr Lapukhov, petr_at_INE.com
CCIE #16379 (R&S/Security/SP/Voice)
CCDE #20100007
Internetwork Expert, Inc.
http://www.INE.com
Toll Free: 877-224-8987
Outside US: 775-826-4344
Blogs and organic groups at http://www.ccie.net