Re: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)

[John Scudder <[e-mail]>]

Hi Folks,

I’m having a hard time untangling the conversation from the various deeply-nested quotes with different quoting conventions, but I think the only thing for me to address right now is to reiterate my earlier response from September 6 regarding implementation:

> - I can tell you right now that there are not implementations of this version of the draft, strictly speaking, because it calls for a new path attribute, which hasn’t been allocated. [*]
> - On the other hand, as the introduction discusses, Juniper’s earlier implementation, on top of a different attribute number but otherwise substantially the same, has been in the field for quite some time. I will be surprised if there’s a second such implementation, but there are many things I don’t know. :-)


Of course I can’t speak for anyone else.

—John

> On Sep 16, 2022, at 12:32 PM, [e-mail] wrote:
> 
> Sue,
>  
> Please see inline [Bruno2]
>  
>  
> Orange Restricted
> From: Idr <[e-mail]> On Behalf Of Susan Hares
> Sent: Friday, September 16, 2022 2:47 PM
> To: DECRAENE Bruno INNOV/NET <[e-mail]>
> Cc: [e-mail]; [e-mail]
> Subject: Re: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)
>  
> Bruno:
>  
> I’m sorry that part of the email did not come through.  See below along with comments.
>  
> From: [e-mail] <[e-mail]> 
> Sent: Friday, September 16, 2022 8:29 AM
> To: Susan Hares <[e-mail]>
> Cc: [e-mail]; [e-mail]
> Subject: RE: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)
>  
>  
> Sue,
>  
> Thank you for your reply.
> Please see inline [Bruno]
>  
>  
> Orange Restricted
> From: Idr <[e-mail]> On Behalf Of Susan Hares
> Sent: Friday, September 16, 2022 1:20 PM
> To: DECRAENE Bruno INNOV/NET <[e-mail]>
> Cc: [e-mail]; [e-mail]
> Subject: Re: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)
>  
> Bruno:
>  
> I’m sorry this response is so delayed (M to Friday)
> [Bruno] Definitely not an issue on my side.
>  
> From: [e-mail] <[e-mail]> 
> Sent: Monday, September 12, 2022 8:09 AM
> To: Susan Hares <[e-mail]>
> Cc: Alvaro Retana <[e-mail]>; [e-mail]; Dongjie (Jimmy) <[e-mail]>; [e-mail]
> Subject: RE: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)
>  
>  
> Sue,
>  
> Thank you for your clarification questions.
> Please see inline.
>  
>  
> Orange Restricted
> From: Susan Hares <[e-mail]> 
> Sent: Friday, September 9, 2022 8:09 PM
> To: DECRAENE Bruno INNOV/NET <[e-mail]>; [e-mail]
> Subject: RE: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)
>  
> Bruno and John:
>  
> The target for the adoption for draft-scudder-idr-entropy-label-01
> is a bis draft for [RFC6790] to fix a bad RFC.  
>  
> The IDR chairs did start this call for draft-scudder-idr-entropy-label-01
> to compete with draft-ietf-idr-next-hop-capability-08.txt or
> other drafts regarding next hops or bgp attributes
> (e.g. draft-scudder-idr-entropy-label-01 as a “bis” document).   
>  
>  
> Thanks for the info. Why is there a desire from IDR chairs to bring a second solution (draft-scudder-idr-entropy-label) to compete with the first (draft-ietf-idr-next-hop-capability)?
> - Is this that in general two solutions are better than one?
> - Is this that the WG expressed comments/limitations on draft-ietf-idr-next-hop-capability?
>  
> [Sue]:  IDR has in the past standardized the existing solutions on its way to the final solution.  I see this as another case of that approach.  My understanding is that John’s solution has multiple implementations to fix the “bis”.  Draft-ietf-idr-next-hop-capability has nice generic properties, but no implementations. 
> [Bruno2] Assuming that you are referring to the draft being called for adoption, my understanding is that ELCv3 has no implementation. (Note that it has no codepoint allocated)
>  
> [Bruno] Your answer is not showing in my mailer. Would you be kind enough to retype it?
> [Sue2]: let me know if you see it now. 
>  
> [Bruno2] I see it now. Thank you.
>  
> Bruno argues that it would be better to include this in
> draft-ietf-next-hop-capability-08.txt as a fix.
>  
> For this shepherd to monitor this portion of the adoption call,
> I need John and Bruno to provide additional input:
>  
> John: you need to address Bruno’s comments on
>  
> “So ELCv2 is not to be used. But this draft is more or less saying the opposite in Appendix A, therefore I object the content of Appendix A.
> ELCv2 is a proprietary solution. Migrating away of ELCv2 may be handled without the IETF.”
>  
> Bruno: if we are going to consider draft-ietf-next-hop-capability-08.txt
> as alternate short term fix to [RFC 6790] I need to know the following:
>  
> Why do you say that draft-ietf-next-hop-capability is a short term fix, while it 1) fixes the problem and 2) it provides a generic tools to advertise BGP Next-Hop dependent capability which will be needed for current MPLS WG evolutions (In Stack Data, Post Stack Data)?
> Why are you considering draft-ietf-next-hop-capability as the possible alternate while it’s the solution been adopted by the IDR WG. In my opinion those qualifiers “alternate” and “if we are going to consider” would better apply to the recent individual draft (draft-scudder-idr-entropy-label)
>  
> [Sue]: Bruno.  Perhaps it is my English. 
> Short term == are you ready to go to WG LC now?  
>  
> [Bruno] Why not if this helps, minus the fact that so I’m not familiar with the procedure that I’m assuming you’re meaning (WGLC then parking the document in the IDR WG while waiting for 2 implementations?)
> But I’m not sure to see what this would change in term of implementations, publication of RFC, and period of time.
>         [Sue2]:  My question should have been – does draft-ietf-next-hop-capability have 2 implementations?
>         Does draft-ietf-next-hop-capability define an equivalent to draft-scudder-idr-entropy-label-01?
>  
> [Bruno2] Both draft-scudder-idr-entropy-label and draft-ietf-idr-next-hop-capability have no codepoints, so a priori no implementations.
> Personally I’d say that functionally draft-ietf-idr-next-hop-capability is a superset of draft-scudder-idr-entropy-label-01.
>  
> A “bis” == a fix to an existing document’s text errors with no additional content.
> Alternatives ==  alternatives to problem of broken existing document: 1) bis, or 2) bis fix + other
>  
> [Bruno] The WG already has an alternative to the broken document (RFC 6790); it’s draft-ietf-idr-next-hop-capability Why would we need an alternative to this alternative?
>     [Sue]: Because draft-ietf-idr-next-hop-capability does not have implementations now, and the draft-scudder-idr-entropy-label-01 does.
>  
> [Bruno2] I’d be curious to know the implementations of draft-scudder-idr-entropy-label-01. They would be squatting on codepoints.
>                  
>  
> 1) Do you have a specific proposal for adding this fix to
> draft-ietf-next-hop-capability?
>  
> If the WG express the need for a non-transitive BGP attribute in order to avoid the software upgrade on the RR it seems straightforward for draft-ietf-next-hop-capability to replace the non-transitive attribute with a transitive attribute recording the latest BGP NH which has modified the attribute. I don’t recall such request from the IDR WG.
>  
>              [Sue-2]: if you posit that it is straight-forward, I would suggest you write preliminary text. 
>  
> [Bruno2] I did. I have initiated an email thread on the list. https://mailarchive.ietf.org/arch/msg/idr/iSCnMtdzygqt8Opoq8eJvM2CeoM/ I’ll update the draft after collecting the feedback from the WG.
>  
> 2) what is the implementation status is for draft-ietf-next-hop-capability-08.txt.
>  [how many implementations and how many features]? 
>  
> I’m not aware of any publically announced implementation.
> [Sue]:
> No implementations == longer term solution
> in draft-ietf-next-hop-capability-08.txt
>  
> [Bruno] Both draft-scudder-idr-entropy-label and draft-ietf-idr-next-hop-capability have no public implementation. So by this logic, both should be equally named as long-term, and not a reason to duplicate the solutions.
>  
> [Sue]: I have two vendors giving me information on implementations of draft-scudder-idr-entropy-label.  I can take private information on draft-ietf-next-hop-capability-08.txt, if you have vendors implementing this draft.
>  
> [Bruno2] Can the WG have this information public? draft-scudder-idr-entropy-label has no codepoint allocated so those implementations could only be squatting on codepoint.
> So basically, one implementation may define whatever it wants in private, squat on codepoint, deploys the squatted codepoint in a mono vendor environment, and then uses this to have its solution rubber stamped by the WG, including in the presence of an existing solution adopted by the WG. Interesting.
>  
> Regards,
> --Bruno
>  
>  
> How   
> MPLS transitioning away from “Entropy Label for the New Thing”
> does not really impact a “bis” draft.  The focus here is publishing a fix
> to a broken draft.
>  
> - If the focus is publishing a fix for a broken draft, we already have a WG document for this: draft-ietf-idr-next-hop-capability
> - IMO, as we know that we need the signal more than ELC, it looks more futureproof to work on a generic solution. draft-ietf-idr-next-hop-capability provides this generic solution, draft-scudder-idr-entropy-label does not
>  
> [sue-2]: I will comment on this part of your email – once I have caught up to the mail threads.
>  
> [Bruno] Ack. For the record, above comment is from Sue, not Bruno.
> [Sue-2]: Agreed.  I really should have drunk more coffee this morning before typing this response (smile).  I’m afraid the typographical error comes from that point.  
>  
> Regards,
> --Bruno
>  
>  
> Thank you,
> Regards,
> --Bruno
>  
> As shepherd, I expect that John Scudder and Bruno will answer
> these questions as part of their upcoming posts.
>  
> Cheerily, Sue
>  
>  
>  
> From: [e-mail] <[e-mail]> 
> Sent: Thursday, September 8, 2022 10:20 AM
> To: Susan Hares <[e-mail]>; [e-mail]
> Subject: RE: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)
>  
>  
> Sue,
>  
>  
>  
> Orange Restricted
> From: Idr <[e-mail]> On Behalf Of Susan Hares
> Sent: Tuesday, September 6, 2022 10:32 PM
> To: [e-mail]
> Subject: [Idr] WG adoption call for draft-scudder-idr-entropy-label-01 (9/6/2022 to 9/20/2022)
>  
> This begins a 2 week WG Adoption and IPR call for:
> https://datatracker.ietf.org/doc/draft-scudder-idr-entropy-label/
>  
> The co-authors should respond to this message with an IPR statement.
>  
> The specification revised the BGP attribute for Entropy Label Capability.
> The abstract of the document states:
>  
>   “This specification defines the Entropy Label Capability Attribute
>    version 3 (ELCv3), a BGP attribute that can be used to inform an LSP
>    ingress router about an LSP egress router's ability to process
>    entropy labels.  This version of the attribute corrects a
>    specification error in the first version, and an improper code point
>    reuse in the second.
>  
>  
> 1)    We already have a solution for this; an IDR WG document. https://datatracker.ietf.org/doc/html/draft-ietf-idr-next-hop-capability-08
> “This document also defines a Next-Hop capability to advertise the
>    ability to process the MPLS Entropy Label as an egress LSR for all
>    NLRI advertised in the BGP UPDATE.  It updates RFC 6790 with regard
>    to this BGP signaling.”
>  
> I don’t recall that the WG expressed an issue on this solution. Nor asked for the use of a non-transitive attribute.
> Now if there is a compelling reason to use a transitive attribute, this can be discussed by the WG as part of regular WG work on draft-ietf-idr-next-hop-capability. If needed, both drafts may also be merged.
>  
>  
> 2) Initiating a technical comparison of transitive vs non-transitive attribute:
>  
> Non-transitive:
> - require the software upgrade of PE, ASBR, RR
>  
> Transitive:
> - require the software upgrade of PE, ASBR.
> - require the re-implementation, test and debugging of the non-transitive-like filtering.
>  
> All in all, small gain in term of deployability at a small cost in term of implementation. Obviously, “small” is in the eye of the beholder. 
> Regarding software upgrade, the only difference is the BGP Route Reflector which: is a small number of nodes (typically at least two order of magnitude smaller), control plane only / no impact on customers, typically centralized in a very small number of locations, control plane only so very possibly we are talking about a VM or container. I would not call this a ‘forklift upgrade’.
>  
> Again, this is a discussion that we can have on the WG document that we have (draft-ietf-idr-next-hop-capability)
>  
> 3) lack of feature coverage
> draft-ietf-idr-next-hop-capability is a generic tool allowing the advertisement of different kind of BGP Next-hop dependent capabilities. Entropy label is one, but the MPLS WG is currently defining new data plane features (In Stack Data, Post Stack Data) which will require to advertise different type de capabilities, possibly with related parameters. Therefore the general tool is needed. (and some people in the MPLS WG have even proposed to deprecate the Entropy Label for the New Thing, so defining a new BGP Capability just for Entropy Label may seem a bit late). There are other usages for other dataplane such as IOAM (another IDR WG using draft-ietf-idr-next-hop-capability)
>  
> 4) In all cases, I don’t think we need two solutions for this simple problem. (the operational differences are small, a few %)
>  
>  
> In your comments consider:  
> 1) Does this specification fixes errors in versions 1 and 2?
>  
> 2) Are there any additional errors or weakness in this specification
> of version 3?  For example, has this specification clearly described what
> happens if version 1, 2 and 3 exist in a network?
>  
> Not really. As already expressed on the list, what happens if ELCv2 and ELCv1 exist in the network is BGP sessions reset with a major impact on the network.
> So ELCv2 is not to be used. But this draft is more or less saying the opposite in Appendix A, therefore I object the content of Appendix A.
> ELCv2 is a proprietary solution. Migrating away of ELCv2 may be handled without the IETF.
>  
> 3) Will deployment of version 3 of Entropy Label Capability
> BGP attribute aid in fixing problems in current networks?
>  
> 4) Are there enough implementations that this draft should
> Be moved quickly to WG LC?
>  
> There are no implementations of ELCv3.
>  
> Regards,
> --Bruno
>  
> Cheerily, Sue
>  
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