[spring] Dependency Issues (WAS: I-D Action: draft-ietf-spring-bfd-09.txt)

[Alvaro Retana <[e-mail]>]

On January 27, 2024 at 3:00:04 PM, Greg Mirsky wrote:


Greg/authors:

Hi!

> The draft is stable, and the authors believe that it is ready for the WG LC.
> We appreciate your consideration of moving this work forward to the WG LC.


I took a quick look at this document, and we need to address a couple
of dependency-issues before moving closer to WGLC.

[I will provide a more detailed review as we move forward.]


(1) I-D.ietf-spring-mpls-anycast-segments

I-D.ietf-spring-mpls-anycast-segments is listed as an Informative
reference, but it needs to be Normative because it is required in §2:

   If the target segment is an anycast prefix segment
   ([I-D.ietf-spring-mpls-anycast-segments]) the corresponding Anycast
   SID MUST be included in the Target TLV as the very last sub-TLV.
   Also, for BFD Control packet the ingress SR node MUST use precisely
   the same label stack encapsulation, especially Entropy Label
   ([RFC6790]), as for the LSP ping with the BFD Discriminator TLV
that bootstrapped the BFD session. Other operational aspects of using
BFD
   to monitor the continuity of the path to the particular Anycast SID,
   advertised by a group of SR-MPLS capable nodes, will be considered in
   the future versions of the document.

I-D.ietf-spring-mpls-anycast-segments expired almost 4 years ago! :-(

Before we try to revive it, is the reference needed?  This paragraph
is the only one that talks about anycast.  Also, it sounds (from the
last sentence) as if more could be said about anycast, so perhaps all
the considerations can be handled in a future document. (?)


(2) I-D.ietf-mpls-bfd-directed

I-D.ietf-mpls-bfd-directed is a Normative reference and is listed as
one of the options in §3 (Use BFD Reverse Path TLV over Segment Routed
MPLS Tunnel).  However, that document is Experimental, and this one is
on the standards track.

While downrefs are possible, using I-D.ietf-mpls-bfd-directed is
premature.  Not only has the document not become an RFC yet, allowing
for experience on the experiment to be collected, but the reason for
its Experimental status is precisely that the "return path that this
session might be less stable than the
tunnel being tested" [1].

Is the reference required?


Thanks!

Alvaro.


[1] https://datatracker.ietf.org/doc/draft-ietf-mpls-bfd-directed/shepherdwriteup/