Re: [IPv6] [IANA #1273836] [Errata Verified] RFC8754 (7102)

[Erik Kline <[e-mail]>]

I don't personally think that's required.

This erratum clarifies that Segments Left means "segments in the
segment list", not some "logical segments left where the SIDs might
actually be compressed and hold many segments."

This is really how implementations treated it in the first place.  My
understanding is that it's the compressed SID work that raised the
notion of "segments in the vs. 'logical' segments which might be
compressed".

If others care to argue otherwise I've no strong objection.

On Mon, May 29, 2023 at 11:07 AM Amanda Baber via RT
<[e-mail]> wrote:
>
> Hi all,
>
> Should the "Segment Routing Header (SRH)" entry in the Routing Types registry include a reference to this errata report (in addition to the existing reference to RFC 8754)?
>
> You can see the registration here:
>
> https://www.iana.org/assignments/ipv6-parameters
>
> thanks,
>
> Amanda Baber
> IANA Operations Manager
>
> On Mon May 29 04:31:55 2023, [e-mail] wrote:
> > The following errata report has been verified for RFC8754,
> >  "IPv6 Segment Routing Header (SRH)".
> >
> > --------------------------------------
> > You may review the report below and at:
> > https://www.rfc-editor.org/errata/eid7102
> >
> > --------------------------------------
> > Status: Verified
> > Type: Technical
> >
> > Reported by: Darren Dukes <[e-mail]>
> > Date Reported: 2022-08-23
> > Verified by: Erik Kline (IESG)
> >
> > Section: 2
> >
> > Original Text
> > -------------
> > Segments Left:  Defined in [RFC8200], Section 4.4.
> >
> > Corrected Text
> > --------------
> > Segments Left:  Defined in [RFC8200], Section 4.4.
> >  Specifically, for the SRH, the number of segments
> > remaining in the Segment List.
> >
> > Notes
> > -----
> > RFC8754 describes “The encoding of IPv6 segments in the SRH” where
> > IPv6 segments are defined in RFC8402.  RFC8402 describes binding SIDs
> > and adjacency SIDs for SRv6. Both these SID types identify more than a
> > single explicitly listed intermediate node to be visited.
> > The current definition of Segments Left only indicates it is defined
> > in RFC8200, and RFC8200 defines it as “Number of route  segments
> > remaining, i.e., number of explicitly listed intermediate nodes still
> > to be visited before reaching the final destination”.
> >
> > Previous versions of draft-ietf-6man-segment-routing-header (0-11)
> > referenced RFC2460/RFC8200 and described the Segments Left field by
> > use in the SRH; as an index into the Segment List. This was removed in
> > later versions (12/13) to consolidate the use of segments left to be
> > specific to the segment processed (now section 4.3.1).  However, that
> > removed the definition of its meaning in the SRH which led to the
> > current issue.
> >
> > The corrected text restores the meaning of Segments Left for the SRH
> > in relation to Segment List (which is not defined in RFC8200), while
> > still leaving its use during segment processing to the segment
> > definition (section 4.3.1 or future documents).
> >
> > --------------------------------------
> > RFC8754 (draft-ietf-6man-segment-routing-header-26)
> > --------------------------------------
> > Title               : IPv6 Segment Routing Header (SRH)
> > Publication Date    : March 2020
> > Author(s)           : C. Filsfils, Ed., D. Dukes, Ed., S. Previdi, J.
> > Leddy, S. Matsushima, D. Voyer
> > Category            : PROPOSED STANDARD
> > Source              : IPv6 Maintenance
> > Area                : Internet
> > Stream              : IETF
> > Verifying Party     : IESG
>