Subject: Re: [mpls] (no subject)

From: "Carlos Pignataro (cpignata)" <[email-masked]>
Date: Fri, 26 Oct 2018 03:47:46 +0000

Hi,

Cc BFD WG

It would be useful to understand the use case motivation or applicability of this draft, other than it can be done.

I’m also increasingly concerned by confusing scope and definition of specifications.

For example:

https://tools.ietf.org/html/draft-mirsky-mpls-p2mp-bfd-04#section-3.2

3.2.  Non-IP Encapsulation of Multipoint BFD

   Non-IP encapsulation for multipoint BFD over p2mp MPLS LSP MUST use
   Generic Associated Channel (G-ACh) Label (GAL) [RFC5586] at the
   bottom of the label stack followed by Associated Channel Header
   (ACH).  Channel Type field in ACH MUST be set to BFD CV [RFC6428].

First, there’s no definition for non-IP BFD in RFC 5586 — only in RFC 5885.
Second, the specification in RFC 6428 applies to MPLS Transport Profile only. NOT for MPLS, and explicitly NOT for P2MP!

https://tools.ietf.org/html/rfc6428#section-1

   This document specifies the BFD extension and behavior to satisfy the
   CC, proactive CV monitoring, and the RDI functional requirements for
   both co-routed and associated bidirectional LSPs.  Supported
   encapsulations include Generic Associated Channel Label (GAL) /
   Generic Associated Channel (G-ACh), Virtual Circuit Connectivity
   Verification (VCCV), and UDP/IP.  Procedures for unidirectional
   point-to-point (P2P) and point-to-multipoint (P2MP) LSPs are for
   further study.

So, no, this does not work.

RFC 6428 does not have scope for P2MP.
And RFC 5586 does not specify anything for BFD. Instead, what needs to be cited (appropriately and expanded) is RFC 5885

https://tools.ietf.org/html/rfc6428#section-4
      RFC 5884 - BFD CC in UDP/IP/LSP
      RFC 5885 - BFD CC in G-ACh
      RFC 5085 - UDP/IP in G-ACh
       MPLS-TP - CC/CV in GAL/G-ACh or G-ACh

Thanks,

— Carlos Pignataro

On Oct 13, 2018, at 4:24 PM, Greg Mirsky <[email-masked]<mailto:[email-masked]>> wrote:

Dear WG Chairs, et al.,
as the author of the BFD for Multipoint Networks over Point-to-Multi-Point MPLS LSP (draft-mirsky-mpls-p2mp-bfd) I would like to ask you to consider WG adoption call of the draft. The document addresses non-IP encapsulation of p2mp BFD over MPLS LSP that may be useful if the overhead of IP, particularly IPv6, encapsulation is the concern. The base specification of BFD for Multipoint Networks is at this time in IESG LC.

Regards,
Greg
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