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/ -----Original Message----- From: Lsr <lsr-boun...@ietf.org> On Behalf Of The IESG Sent: Thursday, April 22, 2021 10:14 PM To: IETF-Announce <ietf-annou...@ietf.org> Cc: lsr@ietf.org; lsr-cha...@ietf.org; cho...@chopps.org; draft-ietf-lsr-isis-srv6-extensi...@ietf.org; aretana.i...@gmail.com Subject: [Lsr] Last Call: <draft-ietf-lsr-isis-srv6-extensions-14.txt> (IS-IS Extension to Support Segment Routing over IPv6 Dataplane) to Proposed Standard The IESG has received a request from the Link State Routing WG (lsr) to consider the following document: - 'IS-IS Extension to Support Segment Routing over IPv6 Dataplane' <draft-ietf-lsr-isis-srv6-extensions-14.txt> as Proposed Standard The IESG plans to make a decision in the next few weeks, and solicits final comments on this action. Please send substantive comments to the last-c...@ietf.org mailing lists by 2021-05-07. Exceptionally, comments may be sent to i...@ietf.org instead. In either case, please retain the beginning of the Subject line to allow automated sorting. Abstract The Segment Routing (SR) allows for a flexible definition of end-to- end paths by encoding paths as sequences of topological sub-paths, called "segments". Segment routing architecture can be implemented over an MPLS data plane as well as an IPv6 data plane. This document describes the IS-IS extensions required to support Segment Routing over an IPv6 data plane. This documents updates RFC 7370 by modifying an existing registry. The file can be obtained via https://datatracker.ietf.org/doc/draft-ietf-lsr-isis-srv6-extensions/ The following IPR Declarations may be related to this I-D: https://datatracker.ietf.org/ipr/3796/ https://datatracker.ietf.org/ipr/4486/ _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr