Re: [Idr] 1 Week last call on changes to: draft-ietf-idr-bgp-ls-segment-routing-ext-17.txt [3/25/2021 to 4/1/2021]

Alvaro Retana <> Tue, 06 April 2021 17:37 UTC

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From: Alvaro Retana <>
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Date: Tue, 06 Apr 2021 10:36:57 -0700
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To: Susan Hares <>, "Les Ginsberg (ginsberg)" <>, "Ketan Talaulikar (ketant)" <>, "" <>
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Subject: Re: [Idr] 1 Week last call on changes to: draft-ietf-idr-bgp-ls-segment-routing-ext-17.txt [3/25/2021 to 4/1/2021]
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The text is not normative…but I do see your point about duplication.  I’m
fine with not adding the note.



On April 6, 2021 at 1:32:49 PM, Les Ginsberg (ginsberg) ( wrote:

Ketan –

I always prefer NOT to duplicate normative statements found in referenced
documents as there are only two possibilities – neither of which is useful:

1)You will get it right – in which case the text will be redundant

2)You will get it wrong – in which case the text will introduce ambiguity

You have referenced RFC 7794 – I think that should be all that is required.

No change please.


*From:* Idr <> *On Behalf Of * Ketan Talaulikar (ketant)
*Sent:* Tuesday, April 06, 2021 9:09 AM
*To:* Susan Hares <>;
*Subject:* Re: [Idr] 1 Week last call on changes to:
draft-ietf-idr-bgp-ls-segment-routing-ext-17.txt [3/25/2021 to 4/1/2021]

Hello All,

A minor point (IMHO worth clarification) related to this
draft-ietf-idr-bgp-ls-segment-routing-ext has come to my notice out of the
ongoing AD-review and discussion [1] for the

This is related to the Prefix Attribute Flags TLV :

Currently the draft says that for IS-IS they are derived from the IPv4/IPv6
Extended Reachability Attribute Flags sub-TLV as specified in

What we missed (though it is described in RFC7794 sec 2.1), is that for the
X-flag, the value needs to be picked from the IS-IS TLVs 236 and 237.

The proposed changes are in sec 2.3.2 as follows:


      *  IS-IS flags correspond to the IPv4/IPv6 Extended Reachability

         Attribute Flags defined in section 2.1 of [RFC7794]



      *  IS-IS flags correspond to the IPv4/IPv6 Extended Reachability

         Attribute Flags defined in section 2.1 of [RFC7794]. *Note: for*

*         the prefix reachability advertisement via IS-IS TLVs 236*

*         [RFC5308] and 237 [RFC5120], the value of the X-flag to be set*

*         in the BGP-LS TLV is determined from the fixed format of those*

*         IS-IS TLVs instead of the IS-IS IPv4/IPv6 Extended Reachability*

*         Attributes Flags sub-TLV.*


I wanted to check with WG/chairs/AD if this is something that we ought to
fix/update at this stage in the draft.




-----Original Message-----
From: Idr <> On Behalf Of Susan Hares
Sent: 25 March 2021 20:07
Subject: [Idr] 1 Week last call on changes to:
draft-ietf-idr-bgp-ls-segment-routing-ext-17.txt [3/25/2021 to 4/1/2021]


This is a 1 Week WG call for comments the changes to

The comments on this document are only for the changes from -16 to -17.txt

Ketan summarized the changes in his early message with

"This update to the BGP-LS SR draft (that was sitting in the RFC-editor Q
due to misref) was required to the recent changes in the

09 that was the missing reference as part of the AD review.

It updates the references to the Source Router Identifier TLV for OSPF and
introduces a new TLV for the Source OSPF Router-ID TLV to cover the new TLV
introduced by draft-ietf-lsr-ospf-prefix-originator."

It is a fine summary of the changes.

Please send comments if you are concerned about the changes.

Unless comments are heard, the intent is to allow the RFC editor to publish
based on the -17.txt version.

Cheers, Susan Hares


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