Re: [RTG-DIR] Rtgdir early review of draft-ietf-ospf-mpls-elc-09

Peter Psenak <> Thu, 03 October 2019 13:11 UTC

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From: Peter Psenak <>
To: Dhruv Dhody <>,
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Date: Thu, 3 Oct 2019 15:11:14 +0200
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Subject: Re: [RTG-DIR] Rtgdir early review of draft-ietf-ospf-mpls-elc-09
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Hi Dhruv,

please see inline (##PP)

On 12/09/2019 12:11, Dhruv Dhody via Datatracker wrote:
> Reviewer: Dhruv Dhody
> Review result: Has Issues
> Subject: RtgDir Early review: draft-ietf-ospf-mpls-elc-09
> Hello
> I have been selected to do a routing directorate “early” review of this draft.
> ​
> The routing directorate will, on request from the working group chair, perform
> an “early” review of a draft before it is submitted for publication to the
> IESG. The early review can be performed at any time during the draft’s lifetime
> as a working group document. The purpose of the early review depends on the
> stage that the document has reached.
> As this document is in working group last call, my focus for the review was to
> determine whether the document is ready to be published. Please consider my
> comments along with the other working group last call comments.
> For more information about the Routing Directorate, please see
> ​
> Document: draft-ietf-ospf-mpls-elc-09
> Reviewer: Dhruv Dhody
> Review Date: 12-09-2019
> Intended Status: Standards Track
> Summary: I have some minor concerns about this document that I think should be
> resolved before it is submitted to the IESG.
> The draft is focused and straightforward, the reader needs to be aware of
> RFC6790 and draft-ietf-mpls-spring-entropy-label beforehand. I have reviewed
> this and the IS-IS I-D together and you will find similar comments for both
> I-Ds.
> Minor
> *****
> (1) Please use updated requirement language text as per RFC 8174, as you do
> have a mix of upper-case and lower-case terms in your I-D.
>        The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
>        "MAY", and "OPTIONAL" in this document are to be interpreted as
>        described in BCP 14 [RFC2119] [RFC8174] when, and only when, they
>        appear in all capitals, as shown here.

RFC 8174 allows the usage of a mix of upper and lower case. If used in 
lower case "they have their normal English meanings", which is the case 
in this draft. Do you have any specific concerns in that regard?

> (2) Could you mark that the codepoints mentioned in the draft are early
> allocated by IANA? This would make it clear that you are not squatting on them.
> I also suggest following change in Section 7 (IANA Considerations) -
> OLD:
>     This document requests IANA to allocate one flag from the OSPFv2
>     Extended Prefix TLV Flags registry:
>        0x20 - E-Flag (ELC Flag)
>     This document requests IANA to allocate one flag from the OSPFv3
>     Prefix Options registry:
>        0x04 - E-Flag (ELC Flag)
> NEW:
>     IANA is requested to confirm the early allocation of the following
>     code point in the OSPFv2 Extended Prefix TLV Flags registry:
>        0x20 - E-Flag (ELC Flag)
>     IANA is requested to confirm the early allocation of the following
>     code point in the  the OSPFv3 Prefix Options registry:
>        0x04 - E-Flag (ELC Flag)

I'm not sure above is necessary, given that the above text would change 
eventually to simply say which code points have been allocated.

> (3) Section 4, I think a reference to RFC 8476 is needed as well to state the
> ERLD is advertised as part of Node MSD advertisement as defined in [RFC8476].

I have updated the normative reference from 
ietf-isis-segment-routing-msd to RFC 8476.

> As mentioned in my review of the IS-IS I-D, what happens if one receives ERLD
> in the Link MSD advertisement? As per my understanding this is not allowed,
> better to add normative text for the case then.

added a sentence to ignore it in Link MSD Sub-TLV.

> (4) Section 8, suggest to also add one sentence for the impact of advertising
> incorrect ERLD. If there isn't any, that can also be stated.

##PP added the sentence.

> Nits
> ****
> (1) Suggested ordering of sections - ..ELC/ERLD/BGP-LS/ACK..  [matching between


> (2) Section 2, add [I-D.ietf-mpls-spring-entropy-label] for terminology
> reference


> (3) Section 3, Add reference to draft-ietf-mpls-spring-entropy-label for the
> definition and usage of ERLD

The Introduction section has:

"This capability, referred to as Entropy Readable Label Depth (ERLD) as 
defined in[I-D.ietf-mpls-spring-entropy-label]"

Is not that sufficient?

> (4) Section 6,
>     The ERLD MSD-type introduced for OSPF in Section 4 is advertised
>     using the Node MSD TLV (TLV 266) of the BGP-LS Node NLRI Attribute as
>     defined in section 3 of [I-D.ietf-idr-bgp-ls-segment-routing-ext].
> I think you mean draft-ietf-idr-bgp-ls-segment-routing-msd here!

right, corrected it.

> Also, maybe change the title "BGP-LS Extension" as there is no 'extension'
> required, ELC/ERLD is BGP-LS would be automatically supported.

renamed to "Signaling ELC and ERLD in BGP-LS".

> (5) Expand MSD on first use.


> Thanks!
> Dhruv