Re: [OSPF] WG Adoption Poll for "OSPF LLS Extensions for Local Interface ID Advertisement"

Peter Psenak <ppsenak@cisco.com> Tue, 09 May 2017 10:54 UTC

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Date: Tue, 09 May 2017 12:54:08 +0200
From: Peter Psenak <ppsenak@cisco.com>
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To: prz <prz@zeta2.ch>, "Acee Lindem (acee)" <acee@cisco.com>
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Subject: Re: [OSPF] WG Adoption Poll for "OSPF LLS Extensions for Local Interface ID Advertisement"
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Hi Tony,

let me try to clarify.

1. This draft does not change, nor does it conflict with RFC3630 in any way.

2. This draft does not change anything in RFC4203 either. It provides an 
alternative and more generic way to exchange Link Local Identifier on 
the interface. Your are right that in our draft we need to specify the 
behavior in case the mechanism described in RFC4203 AND the new 
mechanism specified in our draft are both active at the same time. We 
will add a new section in a next version that covers this part. I don't 
believe it will be too difficult, given that the value of the Link Local 
Identifier is the same same in both cases, the only difference is the 
the mechanism how it is advertised.

Hopes this helps and moves us forward.

thanks,
Peter

On 08/05/17 06:01 , prz wrote:
> OK, intention clear.
>
> What baffles me: can you specify where the idea of "repurposing"
> existing, implemented and deployed standards RFC comes from? And what
> does that look like in practice? You intend to publish an errata? And
> how will we deal with deployed gear that uses RFC3630 on all interfaces?
> And how will traffic engineering metrics be obtained on interfaces if
> RFC3630 is "repurposed" to some type of interfaces only?
>
> Or do you expect RFC3630 being advertised without the sub-TLV 2 now on
> some kind of interfaces while still using all the others sub-TLVs after
> being "repurposed" and all the tooling rewritten to look for the
> suggested draft while being backwards compatible without having an
> indication what is actually implemented on the combination of both
> routers on both sides of an interface?
>
> Any hack works for a super special deployment case but that seems to be
> suggest an orthogonal, clean standard. Really?
>
> --- tony
>
> On Mon, 8 May 2017 00:13:21 +0000, "Acee Lindem (acee)" <acee@cisco.com>
> wrote:
>
>> From: prz <prz@zeta2.ch <mailto:prz@zeta2.ch>>
>> Date: Sunday, May 7, 2017 at 3:47 PM
>> To: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com
>> <mailto:ginsberg@cisco.com>>
>> Cc: Acee Lindem <acee@cisco.com <mailto:acee@cisco.com>>, OSPF WG List
>> <ospf@ietf.org <mailto:ospf@ietf.org>>
>> Subject: Re: [OSPF] WG Adoption Poll for "OSPF LLS Extensions for
>> Local Interface ID Advertisement"
>>
>>     I try to parse that and am still not clear what you both are saying
>>
>>     1. It seems you both saying that RFC3630 is expected now to be
>>     used on unnumbered only (for which I find no indication) or are
>>     you claiming it's only used that way? Based on which
>>     implementation or document? What is "repurposing"? RFC3630 is a
>>     published Standards track RFC and I don't know what "re-purposing"
>>     standards RFCs means?
>>
>> RFC 3630 is specific to OSPF TE Opaque LSAs and what I’m saying is
>> that for this specific usage for interface ID discovery, the
>> repurposing the TE LSAs is limited to unnumbered interfaces. For the
>> second time, can you confirm???
>>
>>     2. Or are you saying that the new draft will be restricted to
>>     unnumbered only? In which case I expect a new version of draft to
>>     discuss further and agree taht the backwards compat section
>>     colllapses to "unnumbered link" considerations only  ...
>>
>> Absolutely not – the draft that is under WG consideration is for
>> general purpose discovery of interface IDs. I believe this point is
>> clear if you read the draft.
>> Thanks,
>> Acee
>>
>>     ?
>>
>>     --- tony
>>
>>     On Sat, 6 May 2017 18:15:21 +0000, "Les Ginsberg (ginsberg)"
>>     <ginsberg@cisco.com <mailto:ginsberg@cisco.com>> wrote:
>>
>>         Tony –
>>
>>         It is known that link identifiers are useful even in cases of
>>         numbered links e.g. some telemetry applications prefer to use
>>         link identifiers to identify all links (numbered and unnumbered).
>>
>>         So I share Acee’s expectations.
>>
>>            Les
>>
>>         *From:*OSPF [mailto:ospf-bounces@ietf.org] *On Behalf Of *Acee
>>         Lindem (acee)
>>         *Sent:* Saturday, May 06, 2017 10:04 AM
>>         *To:* prz
>>         *Cc:* OSPF WG List
>>         *Subject:* Re: [OSPF] WG Adoption Poll for "OSPF LLS
>>         Extensions for Local Interface ID Advertisement"
>>
>>         Hi Tony,
>>
>>         I’ll have to discuss with the authors - but my impression is
>>         that this would not be limited to unnumbered links.  My
>>         understanding is that the repurposing of link–local OSPF TE
>>         LSAs is only done on unnumbered links so that would be the
>>         main focus of the backward compatibility discussion.
>>
>>         Thanks,
>>
>>         Acee
>>
>>         *From: *prz <prz@zeta2.ch <mailto:prz@zeta2.ch>>
>>         *Date: *Saturday, May 6, 2017 at 12:58 PM
>>         *To: *Acee Lindem <acee@cisco.com <mailto:acee@cisco.com>>
>>         *Cc: *OSPF WG List <ospf@ietf.org <mailto:ospf@ietf.org>>
>>         *Subject: *Re: [OSPF] WG Adoption Poll for "OSPF LLS
>>         Extensions for Local Interface ID Advertisement"
>>
>>             Hey Acee,
>>
>>             1. looking fwd to read the revision with backwards
>>             compatibility section and definition which Hello FSM
>>             states the extension applies to
>>
>>             2. I try to read what you say carefully but please
>>             clarify: there's nothing in rfc5613 that prevents LLC on
>>             any link so do you mean, you suggest  to use this TLV on
>>             unnumbered links _only_?  Or do you suggest that RFC3630
>>             implies somehow that LS TE LSAs are used on unnumbered
>>             links _only_? If so, I don't see anything in the RFC to
>>             this effect ...
>>
>>             --- tony
>>
>>             On Fri, 5 May 2017 15:14:30 +0000, "Acee Lindem (acee)"
>>             <acee@cisco.com <mailto:acee@cisco.com>> wrote:
>>
>>                 Hi Tony,
>>
>>                 The authors will cover this in the next revision.
>>                 Based on discussions, the usage of link-scoped TE LSAs
>>                 is limited to unnumbered point-to-point links. If this
>>                 is the case, the backward compatibility is much
>>                 simpler than the other discussions we’ve been having.
>>
>>                 Thanks,
>>
>>                 Acee
>>
>>                 *From: *prz <prz@zeta2.ch <mailto:prz@zeta2.ch>>
>>                 *Date: *Friday, May 5, 2017 at 11:09 AM
>>                 *To: *Acee Lindem <acee@cisco.com <mailto:acee@cisco.com>>
>>                 *Cc: *OSPF WG List <ospf@ietf.org <mailto:ospf@ietf.org>>
>>                 *Subject: *Re: [OSPF] WG Adoption Poll for "OSPF LLS
>>                 Extensions for Local Interface ID Advertisement"
>>
>>                     Not sure it made it from my other address so rtx
>>                     to the list ...
>>
>>                     A conditional against here ...
>>
>>                     I am fine with adoption if I see a version that
>>                     spells the detailed behavior and especially
>>                     interactions between RFC4302 and this draft in a
>>                     detailed section, i.e. both on, RFC4302 gets
>>                     configured/unconfigured, are the LLS extensions
>>                     advertised on every hello or just until a specific
>>                     state (like ISIS padding thingies) and so on ...
>>
>>                     I'd rather have this now than a LC discussion ...
>>
>>                     The idea is deceptively simple but it is a
>>                     redundant mechanism and those always end causing
>>                     inter-op problems unless cleanly spelled out ...
>>
>>                     --- tony
>>
>
>
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