Re: [mpls-tp] Demultiplexing to BFD sessions

["Shahram Davari" <[e-mail]>]

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]<mailto:[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]> [mailto:[e-mail]<mailto:[e-mail]>] On Behalf Of Mach Chen
Sent: Friday, June 11, 2010 3:05 AM
To: Mukund Mani; [e-mail]<mailto:[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]<mailto:[e-mail]>>
Sent: Friday, June 11, 2010 2:24 PM
To: <[e-mail]<mailto:[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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