Re: [mpls-tp] Demultiplexing to BFD sessions

["Adrian Farrel" <[e-mail]>]

Greg'n'Shahram,

Please do check the terminology with the Survivability Framework.
It is (just) not too late to tweak if we have got something wrong or left 
something out.

cheers,
Adrian
----- Original Message ----- 
From: "Greg Mirsky" <[e-mail]>
To: "Shahram Davari" <[e-mail]>
Cc: "Mukund Mani" <[e-mail]>om>; <[e-mail]>
Sent: Friday, June 11, 2010 8:02 PM
Subject: Re: [mpls-tp] Demultiplexing to BFD sessions


> Hi Shahram,
> yes, we need to settle on terminology related to protection.
> It was discussed and presented at the last IETF meeting how bi-directional
> BFD session easily can operate in, effectively, unidirectional mode. I 
> think
> that operating BFD session in this mode is applicable to unidirectional 
> and
> associated bi-directional p2p LSPs.
>
> Regards,
> Greg
>
> On Fri, Jun 11, 2010 at 11:54 AM, Shahram Davari 
> <[e-mail]>wrote;wrote:
>
>>  Hi Greg,
>>
>>
>>
>> I assume by independent protection mode you mean unidirectional 
>> protection.
>> If unidirectional protection is required, then it is simpler to not use
>>  bidirectional BFD session.
>>
>>
>>
>> Regards,
>>
>> Shahram
>>
>>
>>
>> *From:* Greg Mirsky [mailto:[e-mail]]
>> *Sent:* Friday, June 11, 2010 11:18 AM
>> *To:* Shahram Davari
>> *Cc:* Mach Chen; Mukund Mani; [e-mail]
>>
>> *Subject:* Re: [mpls-tp] Demultiplexing to BFD sessions
>>
>>
>>
>> Dear Shahram,
>> assume one BFD session is applied to an associated bi-directional LSP. 
>> Then
>> failure in one direction will bring the session in Down state which is 
>> not
>> desired behavior for independent protection mode. Thus, I think, need for
>> two BFD, in essence unidirectional, sessions.
>>
>> Regards,
>> Greg
>>
>> On Fri, Jun 11, 2010 at 11:03 AM, Shahram Davari <[e-mail]>
>> wrote:
>>
>> Hi,
>>
>> Why would one need to run more than one BFD session over an LSP?
>>
>> Thanks,
>> Shahram
>>
>>
>> -----Original Message-----
>> From: [e-mail] [mailto:[e-mail]] On 
>> Behalf
>> Of Mach Chen
>> Sent: Friday, June 11, 2010 3:05 AM
>> To: Mukund Mani; [e-mail]
>> Subject: Re: [mpls-tp] Demultiplexing to BFD sessions
>>
>> Hi Mukund,
>>
>> I also have the same question about this.
>>
>> As to the BFD discriminator, IMHO, we should keep using it as it be,
>> because
>> it may not be enough to demultiplex the BFD session only based on the
>> label,
>> this is especially true when there are more than two BFD sessions over 
>> the
>> LSP.
>>
>> BTW, it seems that explicit null label distribution is not excluded (and
>> IMHO it should be excluded as PHP) in MPLS-TP (do I miss something?) , 
>> and
>> it is one of the issues that LSP-Ping for BFD session bootstrap is trying
>> to
>> reslove.
>>
>> Best regards,
>> Mach
>>
>> --------------------------------------------------
>> From: "Mukund Mani" <[e-mail]>
>> Sent: Friday, June 11, 2010 2:24 PM
>> To: <[e-mail]>
>> Subject: [mpls-tp] Demultiplexing to BFD sessions
>>
>> > Hi TP-Group
>> > **
>> > *draft-ietf-mpls-tp-lsp-ping-bfd-procedures-00 *states in Section 3
>> >
>> > "When using BFD over MPLS-TP LSPs, the BFD discriminator MUST either be
>> > signaled via LSP-Ping or be statically configured."
>> >
>> > *draft-ietf-mpls-tp-bfd-cc-cv-00 *states in Section 3.5.6
>> >
>> > "MPLS labels at peer MEPs are used to provide context for the received
>> BFD
>> > packets."
>> >
>> > As I understand from the statement in the CC/CV draft, since
>> discriminator
>> > values are not required for demultiplexing to the BFD session anymore, 
>> > we
>> > will not need LSP Ping to bootstrap BFD session for TP LSP.
>> >
>> > But *draft-ietf-mpls-tp-lsp-ping-bfd-procedures-00 *specifies that LSP
>> > Ping
>> > can also be used to signal BFD discriminator.
>> >
>> > So is LSP Ping still really needed in the context of BFD over MPLS-TP?
>> >
>> > Also as a part of MPLS-TP OAM could somebody explain why such a 
>> > deviation
>> > is
>> > taken from the BFD-BASE mode of demultiplexing which even BFD-MPLS uses
>> > (discriminator values instead of MPLS labels), but MPLS-TP goes in for
>> > demultiplexing using labels....
>> >
>> > Could somebody please clarify this..?
>> >
>> >
>> > With Regards
>> > Mukund
>> > <http://tools.ietf.org/html/draft-ietf-mpls-tp-bfd-cc-cv-00>
>> >
>>
>>
>>
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>> >
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