Hi Xuesong, Clarification question: are you talking about interoperability (between two nodes) or compliancy (between an implementation and the RFC)? If the former, could you please spell out the interop issue?
Thanks, Best regards, --Bruno From: Lsr [mailto:lsr-boun...@ietf.org] On Behalf Of Gengxuesong (Geng Xuesong) Sent: Wednesday, May 12, 2021 9:16 AM To: Les Ginsberg (ginsberg) <ginsb...@cisco.com>; Shraddha Hegde <shraddha=40juniper....@dmarc.ietf.org>; Alvaro Retana <aretana.i...@gmail.com>; Peter Psenak (ppsenak) <ppse...@cisco.com>; lsr@ietf.org Cc: cho...@chopps.org; draft-ietf-lsr-isis-srv6-extensi...@ietf.org; Van De Velde, Gunter (Nokia - BE/Antwerp) <gunter.van_de_ve...@nokia.com> Subject: Re: [Lsr] Last Call: <draft-ietf-lsr-isis-srv6-extensions-14.txt> (IS-IS Extension to Support Segment Routing over IPv6 Dataplane) to Proposed Standard Hi Les, Prefix Attributes sub-TLV is necessary when locator is leaked. So we are not against Prefix Attribute sub-TLV implementation. We just propose to keep it optional ("should" rather than "must") for interoperability. Best Xuesong From: Les Ginsberg (ginsberg) [mailto:ginsb...@cisco.com] Sent: Wednesday, May 12, 2021 6:29 AM To: Shraddha Hegde <shraddha=40juniper....@dmarc.ietf.org<mailto:shraddha=40juniper....@dmarc.ietf.org>>; Alvaro Retana <aretana.i...@gmail.com<mailto:aretana.i...@gmail.com>>; Peter Psenak (ppsenak) <ppse...@cisco.com<mailto:ppse...@cisco.com>>; lsr@ietf.org<mailto:lsr@ietf.org>; Gengxuesong (Geng Xuesong) <gengxues...@huawei.com<mailto:gengxues...@huawei.com>> Cc: cho...@chopps.org<mailto:cho...@chopps.org>; draft-ietf-lsr-isis-srv6-extensi...@ietf.org<mailto:draft-ietf-lsr-isis-srv6-extensi...@ietf.org>; Van De Velde, Gunter (Nokia - BE/Antwerp) <gunter.van_de_ve...@nokia.com<mailto:gunter.van_de_ve...@nokia.com>> Subject: RE: [Lsr] Last Call: <draft-ietf-lsr-isis-srv6-extensions-14.txt> (IS-IS Extension to Support Segment Routing over IPv6 Dataplane) to Proposed Standard Shraddha/ Xuesong - Since Prefix Attributes sub-TLV is required for correct operation when a Locator is leaked, would it be safe to assume that your implementations either do not leak Locators or you advise your customers not to deploy this feature with multiple levels? The problem with allowing the sub-TLV to be optional is that if the sub-TLV is omitted you cannot tell whether the Locator has been leaked - so you don't know whether you have a problem or not. The safest thing to do is require prefix-attributes sub-TLV always - then you can guarantee that if the prefix is leaked the necessary information will be present. Anything else leaves us vulnerable. We all appreciate interoperability considerations, but frankly this is a gap that needs to be closed to support correct operation. Les From: Lsr <lsr-boun...@ietf.org<mailto:lsr-boun...@ietf.org>> On Behalf Of Shraddha Hegde Sent: Tuesday, May 11, 2021 8:21 AM To: Alvaro Retana <aretana.i...@gmail.com<mailto:aretana.i...@gmail.com>>; Peter Psenak (ppsenak) <ppse...@cisco.com<mailto:ppse...@cisco.com>>; lsr@ietf.org<mailto:lsr@ietf.org> Cc: cho...@chopps.org<mailto:cho...@chopps.org>; draft-ietf-lsr-isis-srv6-extensi...@ietf.org<mailto:draft-ietf-lsr-isis-srv6-extensi...@ietf.org>; Van De Velde, Gunter (Nokia - BE/Antwerp) <gunter.van_de_ve...@nokia.com<mailto:gunter.van_de_ve...@nokia.com>> Subject: Re: [Lsr] Last Call: <draft-ietf-lsr-isis-srv6-extensions-14.txt> (IS-IS Extension to Support Segment Routing over IPv6 Dataplane) to Proposed Standard Juniper has an implementation of SRv6 that does not support Prefix attributes sub-tlv in locator TLV. We would prefer not to change the optional sub-TLV to MUST. Rgds Shraddha Juniper Business Use Only From: Lsr <lsr-boun...@ietf.org<mailto:lsr-boun...@ietf.org>> On Behalf Of Alvaro Retana Sent: Friday, May 7, 2021 7:23 PM To: Peter Psenak <ppse...@cisco.com<mailto:ppse...@cisco.com>>; lsr@ietf.org<mailto:lsr@ietf.org> Cc: cho...@chopps.org<mailto:cho...@chopps.org>; draft-ietf-lsr-isis-srv6-extensi...@ietf.org<mailto:draft-ietf-lsr-isis-srv6-extensi...@ietf.org>; Van De Velde, Gunter (Nokia - BE/Antwerp) <gunter.van_de_ve...@nokia.com<mailto:gunter.van_de_ve...@nokia.com>> Subject: Re: [Lsr] Last Call: <draft-ietf-lsr-isis-srv6-extensions-14.txt> (IS-IS Extension to Support Segment Routing over IPv6 Dataplane) to Proposed Standard [External Email. Be cautious of content] On May 3, 2021 at 5:17:58 AM, Peter Psenak wrote: > Technically I agree with you and if everybody agrees, I'm fine to > enforce the presence of the Prefix Attribute Flags TLV in the Locator TLV. So...what does everyone else think? We need to close on this point before the IESG evaluates the document. I'm requesting it to be put on the May/20 telechat, which means that we should have a resolution and updated draft by the end of next week. Thanks! Alvaro. On May 3, 2021 at 5:17:58 AM, Peter Psenak (ppse...@cisco.com<mailto:ppse...@cisco.com>) wrote: Hi Gunter, Prefix Attribute Flags Sub-TLV has been defined as an optional Sub-TLV. The problem you describe is not specific to Locator TLV, same applies to regular IPv4/v6 prefixes (forget SR MPLS for a while) - if the Prefix Attribute Flags TLV is not included, one can not tell whether the prefix has been propagated (L1->L2) or generated as a result of the local interface attached on the originator. Same applies to redistribution and R-flag for IPv4 prefix TLVs. SRv6 Locator TLV has been defined a while back and the Prefix Attribute Flags Sub-TLV has always been an optional Sub-TLV of it. I'm not sure we can start to mandate the Prefix Attribute Flags TLV at this point. Technically I agree with you and if everybody agrees, I'm fine to enforce the presence of the Prefix Attribute Flags TLV in the Locator TLV. thanks, Peter On 03/05/2021 10:45, Van De Velde, Gunter (Nokia - BE/Antwerp) wrote: > Hi Peter, All, > > Could we update to "draft-ietf-lsr-isis-srv6-extensions" that the > prefix-attribute tlv is mandatory when a locator is redistributed? > > Why? > *When calculating a LFA for an SRv6 End.SID we better know if the locator has > been redistributed or not for a correct operation. > > Reasoning: > * A locator has the D bit. This one is set when we redistribute from L2 to L1. > ** So this end-sid will not be used as we know that it is redistributed. > > * In the other direction (L1-L2), we only know that a locator is > redistributed from L1 to L2 if the prefix-attribute sub-tlv is advertised. > ** This means if the operator does not configure advertisement of the > prefix-attribute tlv, ISIS could potentially use an end-sid which does not > terminate on the expected node. > > * Compared to sr-mpls, a prefix-sid has the R flag indicating it is > redistributed. > * We don't have that for locator end-sids. > > Relevant snip from " draft-ietf-lsr-isis-srv6-extensions" > > 7.1. SRv6 Locator TLV Format > > The SRv6 Locator TLV has the following format: > > 0 1 2 3 > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > | Type | Length |R|R|R|R| MT ID | > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > Type: 27 > > Length: variable. > > R bits: reserved for future use. They MUST be > set to zero on transmission and MUST be ignored on receipt. > > MT ID: Multitopology Identifier as defined in [RFC5120]. > Note that the value 0 is legal. > > Followed by one or more locator entries of the form: > > 0 1 2 3 > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > | Metric | > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > | Flags | Algorithm | > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > | Loc Size | Locator (variable)... > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > | Sub-TLV-len | Sub-TLVs (variable) . . . | > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > Metric: 4 octets. As described in [RFC5305]. > > Flags: 1 octet. The following flags are defined > > 0 > 0 1 2 3 4 5 6 7 > +-+-+-+-+-+-+-+-+ > |D| Reserved | > +-+-+-+-+-+-+-+-+ > > where: > D-flag: Same as described in section 4.1. of [RFC5305]. > > > G/ > _________________________________________________________________________________________________________________________ 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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