Bruno -

First, without dismissing your comments, this is a WG adoption call - not a 
Last Call to publish a draft as an RFC (as Tony has pointed out).
Could you state unambiguously whether you support adoption or not?

I am in agreement with Tony's responses. I think my earlier reply to you is 
very much consistent with Tony's reply.

Some additional responses inline.

From: bruno.decra...@orange.com <bruno.decra...@orange.com>
Sent: Tuesday, November 21, 2023 9:27 AM
To: Tony Li <tony...@tony.li>
Cc: Yingzhen Qu <yingzhen.i...@gmail.com>; 
draft-pkaneria-lsr-multi-...@ietf.org; lsr <lsr@ietf.org>
Subject: RE: [Lsr] WG Adoption Call - draft-pkaneria-lsr-multi-tlv (11/17/2023 
- 12/09/2023)

Hi Tony,

Thanks for your replies. Much appreciated

Please see inlines [Bruno]
In any case, that's fine to have a different perspective because we do (e.g., 
vendor vs operator)



Orange Restricted
From: Tony Li <tony1ath...@gmail.com<mailto:tony1ath...@gmail.com>> On Behalf 
Of Tony Li
Sent: Tuesday, November 21, 2023 5:45 PM
To: DECRAENE Bruno INNOV/NET 
<bruno.decra...@orange.com<mailto:bruno.decra...@orange.com>>
Cc: Yingzhen Qu <yingzhen.i...@gmail.com<mailto:yingzhen.i...@gmail.com>>; 
draft-pkaneria-lsr-multi-...@ietf.org<mailto:draft-pkaneria-lsr-multi-...@ietf.org>;
 lsr <lsr@ietf.org<mailto:lsr@ietf.org>>
Subject: Re: [Lsr] WG Adoption Call - draft-pkaneria-lsr-multi-tlv (11/17/2023 
- 12/09/2023)


Hi Bruno,

Thank you for your comments.


As a constructive proposal, and as mitigations, I would like the document be 
improved with the following changes:

a.       Sending MUST be controlled by configuration [1]
[1]
OLD: It is RECOMMENDED that implementations which support the sending of 
MP-TLVs provide configuration controls to enable/disable generation of MP-TLVs.
NEW: It is REQUIRED that implementations which support the sending of MP-TLVs 
provide configuration controls to enable/disable generation of MP-TLVs.


As you know, some systems already generate multi-part TLVs. And they lack any 
controls for doing this today. The language that you're suggesting would make 
these systems immediately out of compliance, thereby punishing them for 
providing leading technology.

[Bruno] Personally, I'd prefer that the LSR WG works on making a good long term 
specification for people using it rather than accommodate short term aspects 
such as pre-standard implementations. (Plus some implementations have no 
problem with claiming support for an RFC while not following the spec (e.g., 
RFC 3107).)
If we are to the point that 1) the argument to adopt MP-TLV is because it's 
already implemented by some implementations, plus that 2) we can't change 
anything in the draft because there are pre-standard implementations (even if 
agree that it would be better cf "[LES:] In principle I agree." [A]) then let's 
just rubberstamp those implementations and close the WG.


Furthermore, it is highly unlikely that any implementation is going to actually 
comply just because of our choice of adjective here.
[Bruno] Exactly my above point: existing implementations may not bother and 
claims compliancy anyway. So, what's the problem with changing the text in the 
draft?

The control is clearly not necessary for interoperability and we should not 
overuse our ability to place requirements on implementations. We all know that 
the real power comes from customers who place requirements on vendors and the 
requirements that we place in RFCs are only meaningful when describing the 
requirements for correct operation of our protocols. Overextending ourselves 
dilutes our interoperability requirements.
[Bruno] In my perspective, the control is required to not break existing 
networks.
I agree with you that this is not required for interoperability with other 
MP-TLV implementations, but to me this is required for interoperability with 
RFCs having specified the existing TLVs

a.

b.       For existing TLVs (and "any level of sub-TLVs"), details the TLV which 
could be advertised with no risks for the network and TLVs which must not be 
advertised before all nodes be upgraded.


What is 'no risk'? We are not competent to make that assesment. That requires 
knowing everything about every implementation, past, present, and future and 
testing the full cross product of those implementations in all possible 
scenarios.

[Bruno] I was referring to Les email [A], in particular "[LES:] Again, this 
depends on the codepoint. In the case of Neighbor/Prefix Reachability 
advertisements, the impact on forwarding is highly likely (as your wording 
states). "
[A] https://mailarchive.ietf.org/arch/msg/lsr/jZJi3xe8BcEpmlAG-P_LfSf-FgY/

[LES:] It is out of scope for the MP draft to specify what risks may be 
associated with each and every codepoint that has the potential to require use 
of MP.
Such an analysis would be lengthy and inaccurate and bloat the draft to no 
useful purpose. It took 20 years before MP usage for Neighbor/Prefix 
advertisements became a realistic deployment scenario. Do you believe that 
folks 20 years ago could have accurately predicted the risks for these two TLVs?

b.

c.       Given this document typically may require global support before this 
be enabled, I think this draft would be a good candidate for the addition of 
the relevant yang module as per draft-qgp-lsr-isis-pics-yang [3]. I personally 
don't see a problem with adding a normative reference to an individual draft, 
but if I'm wrong, an option for the chairs to consider would be to pause this 
adoption call and start an adoption call for draft-qgp-lsr-isis-pics-yang.


That would stall this document indefinitely, pending progress on the YANG 
model. Please recall that this document is already two years old and that this 
is an adoption call, NOT WGLC.

[Bruno] At worst that may only delay RFC publication. All other steps would not 
be delayed so I don't think that this would delay the feature.
Plus draft-qgp-lsr-isis-pics-yang seems short to me and could probably even be 
made even shorter if needed. So eventually it could be progressed quickly.

[LES:] While I would like to believe that progress on 
draft-qgp-lsr-isis-pics-yang will be swift, I think the initial feedback we 
have received suggests otherwise. There have already been a number of 
differences of opinion as to appropriate content and this is an important 
discussion to have because we are setting a template for many such drafts in 
the future.
I also argue that the two drafts are logically not related. The PICS draft is 
addressing the need for operators to be able to obtain an accurate 
implementation report for the routers in a network. This isn't specific to the 
use of MP and in fact isn't directly related to MP at all.
MP has only highlighted that in order to safely deploy features in a network 
operators need such information - which is an existing problem.

The question on the table is not whether this document is perfect. The question 
is whether this is worth continuing to work on and whether this document is the 
correct basis for that work. I would like to see this document published 
sometime this century.
[Bruno] Indeed. And the related question is whether the WG is allowed to modify 
the content of that document or whether the document is as-is because there 
exist pre-standards implementations.


[LES:] I don't understand your response. Further discussion of the content of 
the MP draft will happen post adoption - just as it has for every other 
document which has been adopted in the history of the IETF.
Further, the heart of the document is explanatory/informational - not 
normative. I don't see risk that "early implementations" will not interoperate 
with implementations based on later versions of the draft because the draft is 
not altering protocol behavior.
There is only one new codepoint introduced in the document (capabilities 
advertisement) and that has been explicitly defined to not be required so as 
not to introduce interoperability issues.

   Les


Regards,
--Bruno

Regards,
Tony


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