Re: [mpls-tp] Demultiplexing to BFD sessions

Hi Mukund,

To my understanding, discriminator exchange is applicable in some 
scenario, but not necessary in other scenario, for BFD session bootstrap.

In RFC5884 section 3.2, it's indicated that LSP Ping is used to exchange 
discriminator and bootstrap the BFD session; But in RFC5885 section 3.1, 
it's also indicated that the VCCV control channel provides the context 
required to bootstrap the BFD session and no discriminator exchange 
needed.

In the MPLS-TP context, IMO it's similar to the scenario in RFC5885 and no 
discriminator exchange is needed to bootstrap BFD session.

Best Regards,
Xiao Min

Mukund Mani <mukund.mani@gmail.com> 
发件人:  mpls-tp-bounces@ietf.org
2010-06-11 14:24

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[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
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