Bruno – Thanx for the concerns.
Let’s dig deeper into the concerns about “interoperability”. I will use IS Neighbors advertisements in this discussion – but conceptually the discussion applies to all codepoints – though obviously the specifics are different in each case. It is important to note that this draft has not introduced any modification to the encoding of any existing TLV. The format and the set of sub-TLVs associated with a given codepoint are defined in the respective RFCs for each codepoint and are not altered by this draft. In the case of IS-Neighbor, the correct identification of keys is already required for two reasons: 1)It determines the identity of the link/neighbor being advertised 2)It is necessary in order to correctly do two-way connectivity checking Independent of multi-TLV, implementations MUST correctly process the keys or operation of the network is compromised. The interoperability issues associated with multi-tlv do not arise because existing specifications are ambiguous as to what constitutes a key. Interoperability issues result from some implementations treating two TLVs with matching keys in different ways: Historically two TLVs with the same key have been treated as replacements for each other i.e., one TLV is treated as “stale” and one TLV is treated as the “current”. With multi-TLV, two TLVs with the same key are treated as complementary i.e., the information in both TLVs is treated as current. If all routers in the network don’t apply the same interpretation to multiple TLVs with the same key, then we have (obvious) interoperability issues. This is what is discussed in the draft and is the proper subject of the draft. Keys for each TLV are defined in the respective RFCs that define each codepoint. Repeating that information in this draft is at best redundant – at worst unintentionally conflicting – and clearly does not scale (we have hundreds of codepoints to which multi-TLV can be applied). This is why we made the decision not to specify/discuss the “key” for every TLV – but focused on the conceptual use of the key in support of multi-TLV. Les From: bruno.decra...@orange.com <bruno.decra...@orange.com> Sent: Tuesday, August 6, 2024 3:36 AM To: Les Ginsberg (ginsberg) <ginsb...@cisco.com>; Ketan Talaulikar <ketant.i...@gmail.com>; Yingzhen Qu <yingzhen.i...@gmail.com> Cc: lsr <lsr@ietf.org>; lsr-chairs <lsr-cha...@ietf.org> Subject: RE: [Lsr] Re: WG Last Call for draft-ietf-lsr-multi-tlv (7/1/2024 - 7/15/2024) Thanks Les for your reply. Please see 1 comment inline [Bruno] From: Les Ginsberg (ginsberg) <ginsberg=40cisco....@dmarc.ietf.org<mailto:ginsberg=40cisco....@dmarc.ietf.org>> Sent: Wednesday, July 3, 2024 8:53 PM To: Ketan Talaulikar <ketant.i...@gmail.com<mailto:ketant.i...@gmail.com>>; Yingzhen Qu <yingzhen.i...@gmail.com<mailto:yingzhen.i...@gmail.com>> Cc: lsr <lsr@ietf.org<mailto:lsr@ietf.org>>; lsr-chairs <lsr-cha...@ietf.org<mailto:lsr-cha...@ietf.org>> Subject: [Lsr] Re: WG Last Call for draft-ietf-lsr-multi-tlv (7/1/2024 - 7/15/2024) CAUTION : This email originated outside the company. Do not click on any links or open attachments unless you are expecting them from the sender. ATTENTION : Cet e-mail provient de l'extérieur de l'entreprise. Ne cliquez pas sur les liens ou n'ouvrez pas les pièces jointes à moins de connaitre l'expéditeur. Ketan – Thanx for the support. Responses inline. From: Ketan Talaulikar <ketant.i...@gmail.com<mailto:ketant.i...@gmail.com>> Sent: Wednesday, July 3, 2024 9:56 AM To: Yingzhen Qu <yingzhen.i...@gmail.com<mailto:yingzhen.i...@gmail.com>> Cc: lsr <lsr@ietf.org<mailto:lsr@ietf.org>>; lsr-chairs <lsr-cha...@ietf.org<mailto:lsr-cha...@ietf.org>> Subject: [Lsr] Re: WG Last Call for draft-ietf-lsr-multi-tlv (7/1/2024 - 7/15/2024) Hi All, I thank the authors for the work on this draft and support its publication. This work was very much needed for the enablement of new feature sets in ISIS networks and the specification will aid interoperability. My only "grudge" is something that I have brought up previously on this draft [1] and perhaps there may still be some interest in the WG/authors to take care of them? 1) Mandate that the non-key part is identical in all the parts and if not recommend that the value in the first part is taken. Or, say something about handling this condition than saying "error and out of scope". [LES:] The authors discussed this aspect. What we decided was that the scope of this draft was to clearly define the generic aspects of multi-tlv – not to discuss the peculiarities of any specific codepoint. With that in mind, Section 4 – and specifically the examples provided – is meant only to illustrate what a “key” is. There is considerably more that could be said about each specific codepoint – but we believe that is out of scope for this document. 2) Since the early versions of the draft, a lot of effort has been put on cataloguing TLV/sub-TLVs and their applicability for MP. From there, it is only one more step to actually specify the "key" and "non-key" parts of TLVs (where this is not done already) in an appendix section. This is important for interoperability. The draft today covers two of the most prominent TLVs but does not cover the others. [LES:] Again, the intent of this document is to clearly describe the generic Multi-TLV mechanism – not to discuss the specifics of each codepoint. To do so would expand the scope of the document beyond any reasonable boundaries. For example, in the case of Neighbor TLVs (such as TLV 22), there are a wide variety of implementation strategies. Some implementations send only LinkIDs all the time. Some implementations send endpoint addresses (when available) and not Link IDs. Some implementations send endpoint addresses and Link IDs. All of these options are valid – but may impact interoperability depending on the “generosity” of the receivers. [Bruno] I think that interoperability is important, especially for a link state IGP. If interop depends on the “generosity” of the receivers, why not specifying (I mean mandating with MUST) the level of generosity which is required for interop (well I mean “for things to work”) Thanks, --Bruno And some commonality is required – independent of Multi-TLV – in order for two-way connectivity check to work correctly. It is not in the scope of this document to include such a discussion – and the use of Multi-TLV does not introduce new issues in this regard. This is why we restricted ourselves to only discussing “what a key is” in the examples. The discussion – even for the two examples - is not exhaustive and is not meant to be. If there is a significant interoperability issue with a particular codepoint, some other document will have to be written/updated to address that. Les That said, I won't hold this document if I am in the rough on this. Thanks, Ketan [1] https://mailarchive.ietf.org/arch/msg/lsr/qQkeAHnw2qjrGoySbES4EVafgY4/ On Tue, Jul 2, 2024 at 11:39 AM Yingzhen Qu <yingzhen.i...@gmail.com<mailto:yingzhen.i...@gmail.com>> wrote: Hi, This email begins a 2 week WG Last Call for the following draft: draft-ietf-lsr-multi-tlv-01 - Multi-part TLVs in IS-IS<https://datatracker.ietf.org/doc/draft-ietf-lsr-multi-tlv/> Please review the document and indicate your support or objections by July 15th, 2024. Authors, Please indicate to the list, your knowledge of any IPR related to this work. Thanks, Yingzhen _______________________________________________ Lsr mailing list -- lsr@ietf.org<mailto:lsr@ietf.org> To unsubscribe send an email to lsr-le...@ietf.org<mailto:lsr-le...@ietf.org> ____________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. 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