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

"Acee Lindem (acee)" <> Mon, 08 May 2017 14:19 UTC

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From: "Acee Lindem (acee)" <>
To: prz <>
CC: OSPF WG List <>
Thread-Topic: [OSPF] WG Adoption Poll for "OSPF LLS Extensions for Local Interface ID Advertisement"
Date: Mon, 08 May 2017 14:19:06 +0000
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Subject: Re: [OSPF] WG Adoption Poll for "OSPF LLS Extensions for Local Interface ID Advertisement"
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From: prz <<>>
Date: Monday, May 8, 2017 at 12:16 AM
To: prz <<>>
Cc: Acee Lindem <<>>, OSPF WG List <<>>
Subject: Re: [OSPF] WG Adoption Poll for "OSPF LLS Extensions for Local Interface ID Advertisement"

Having thought a bit about it a possible idea is to think whether the suggested TLV 18 would try to take precedence over sub-TLV 2 in TLV on RFC3630.

That has another interesting problem. 3630 does not talk about scope of the opaque in normative language (Shraddha suggested it's link local but it looks like she was talking about 4203 in fact) but 3630 allures in Introduction that it's type 10 (area scope) talking about "flooding rules" which would make the "preference" idea null and void.

So IMO we have a really interesting backwards section here with deployed 4203 and 3630 backwards compatibility considerations.

The application we are talking about here is neighbor interface ID discovery and what Shraddha has, in fact, suggested is link-local flooding scope. Many see usage of TE Opaque LSAs for non-TE purposes as repurposing while one implementation sees it as a deployed standard. I think we have discussed to the point of impasse and further discussion is circular and would only impede WG progress. The OSPF LLS Interface ID draft will address backward compatibility.


--- tony

On Sun, 07 May 2017 21:01:33 -0700, 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)" wrote:

From: prz <<>>
Date: Sunday, May 7, 2017 at 3:47 PM
To: "Les Ginsberg (ginsberg)" <<>>
Cc: Acee Lindem <<>>, OSPF WG List <<>>
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.


--- tony

On Sat, 6 May 2017 18:15:21 +0000, "Les Ginsberg (ginsberg)" <<>> 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.


From: OSPF [] 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.


From: prz <<>>
Date: Saturday, May 6, 2017 at 12:58 PM
To: Acee Lindem <<>>
Cc: OSPF WG List <<>>
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)" <<>> 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.
From: prz <<>>
Date: Friday, May 5, 2017 at 11:09 AM
To: Acee Lindem <<>>
Cc: OSPF WG List <<>>
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