Re: [RTG-DIR] RtgDir review: draft-ietf-isis-segment-routing-extensions-20

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Sun, 11 November 2018 04:10 UTC

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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
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Thread-Topic: RtgDir review: draft-ietf-isis-segment-routing-extensions-20
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Date: Sun, 11 Nov 2018 04:10:03 +0000
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Subject: Re: [RTG-DIR] RtgDir review: draft-ietf-isis-segment-routing-extensions-20
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Russ -

Thanx for the review.
Responses inline.


> -----Original Message-----
> From: 7riw77@gmail.com <7riw77@gmail.com>;
> Sent: Saturday, November 10, 2018 7:51 AM
> To: rtg-ads@ietf.org
> Cc: rtg-dir@ietf.org; draft-ietf-isis-segment-routing-extensions.all@ietf.org;
> lsr@ietf.org
> Subject: RtgDir review: draft-ietf-isis-segment-routing-extensions-20
> 
> Hello,
> 
> I have been selected as the Routing Directorate reviewer for this draft. The
> Routing Directorate seeks to review all routing or routing-related drafts as
> they pass through IETF last call and IESG review, and sometimes on special
> request. The purpose of the review is to provide assistance to the Routing
> ADs. For more information about the Routing Directorate, please see 
> http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir
> 
> Although these comments are primarily for the use of the Routing ADs, it
> would be helpful if you could consider them along with any other IETF Last
> Call comments that you receive, and strive to resolve them through
> discussion or by updating the draft.
> 
> Document: draft-ietf-isis-segment-routing-extensions-20
> Reviewer: Russ White
> Review Date: 10 November 2018
> IETF LC End Date: 12 December 2018
> Intended Status: Standards Track
> 
> Summary:
> 
> This document is basically ready for publication, but has nits that should be
> considered prior to publication.
> 
> Overall, this document is well written, and the mechanisms described are
> well thought out.
> 
> Major Issues:
> 
> No major issues found.
> 
> Minor Issues:
> 
> No minor issues found.
> 
> Nits:
> 
> Section 2.1
> 
> Algorithms identifiers are defined in Section 3.2.
> 
> "Algorithm" rather than "Algorithms."
> 

[Les:] Ack - thanx.

> Sections 2.1 and 2.2
> 
> "Length" is listed as "variable," but not further definition is provided. From
> the text it seems like valid values here would be 3 or 20, in octets, as this is
> explicit in section 2.3, but it might be good to clarify (ie, just copy the text for
> "Length" in section 2.3 to these sections as well).
> 
[Les:] The length of the sub-TLV  is variable because the length of the SID itself is variable.

Both sections have the text:

<snip>
SID/Index/Label: according to the V and L flags, it contains
      either:

      *  A 4 octet index defining the offset in the SID/Label space
         advertised by this router using the encodings defined in
         Section 3.1.  In this case the V and L flags MUST be unset.

      *  A 3 octet local label where the 20 rightmost bits are used for
         encoding the label value.  In this case the V and L flags MUST
         be set.
<end snip>

The text for Section 2.3 is necessarily different because there is no flags field in the SID/Label sub-TLV and there also are no additional fields in the sub-TLV other than the SID itself.

I therefore think the text as is should be fine - but I am open to suggestion.
Russ - could you review this one more time in light of the above and let me know what you think?

   Les


> 😊 /r