--- 1/draft-ietf-lsr-isis-srv6-extensions-12.txt 2021-04-12 05:13:24.621772510 -0700 +++ 2/draft-ietf-lsr-isis-srv6-extensions-13.txt 2021-04-12 05:13:24.669773711 -0700 @@ -1,35 +1,35 @@ Networking Working Group P. Psenak, Ed. Internet-Draft C. Filsfils Updates: 7370 (if approved) Cisco Systems Intended status: Standards Track A. Bashandy -Expires: October 10, 2021 Individual +Expires: October 14, 2021 Individual B. Decraene Orange Z. Hu Huawei Technologies - April 8, 2021 + April 12, 2021 IS-IS Extension to Support Segment Routing over IPv6 Dataplane - draft-ietf-lsr-isis-srv6-extensions-12 + draft-ietf-lsr-isis-srv6-extensions-13 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 [RFC7370] by modifying an existing registry. + This documents updates RFC 7370 by modifying an existing registry. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Status of This Memo @@ -39,21 +39,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on October 10, 2021. + This Internet-Draft will expire on October 14, 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -71,40 +71,40 @@ 4. Advertising Maximum SRv6 SID Depths . . . . . . . . . . . . . 4 4.1. Maximum Segments Left MSD Type . . . . . . . . . . . . . 5 4.2. Maximum End Pop MSD Type . . . . . . . . . . . . . . . . 5 4.3. Maximum H.Encaps MSD Type . . . . . . . . . . . . . . . . 5 4.4. Maximum End D MSD Type . . . . . . . . . . . . . . . . . 5 5. SRv6 SIDs and Reachability . . . . . . . . . . . . . . . . . 6 6. Advertising Anycast Property . . . . . . . . . . . . . . . . 7 7. Advertising Locators and End SIDs . . . . . . . . . . . . . . 8 7.1. SRv6 Locator TLV Format . . . . . . . . . . . . . . . . . 8 7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10 - 8. Advertising SRv6 Adjacency SIDs . . . . . . . . . . . . . . . 11 + 8. Advertising SRv6 Adjacency SIDs . . . . . . . . . . . . . . . 12 8.1. SRv6 End.X SID sub-TLV . . . . . . . . . . . . . . . . . 12 - 8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 13 - 9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 15 - 10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 16 - 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 - 11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 16 - 11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 17 - 11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 17 - 11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 18 - 11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 18 - 11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 19 - 11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 19 - 11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 20 - 12. Security Considerations . . . . . . . . . . . . . . . . . . . 20 - 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20 - 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 - 14.1. Normative References . . . . . . . . . . . . . . . . . . 21 - 14.2. Informative References . . . . . . . . . . . . . . . . . 24 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 + 8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 14 + 9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 16 + 10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 17 + 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 + 11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 17 + 11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 18 + 11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 18 + 11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 19 + 11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 19 + 11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 20 + 11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 20 + 11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 21 + 12. Security Considerations . . . . . . . . . . . . . . . . . . . 21 + 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 + 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 + 14.1. Normative References . . . . . . . . . . . . . . . . . . 22 + 14.2. Informative References . . . . . . . . . . . . . . . . . 25 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 1. Introduction With Segment Routing (SR) [RFC8402], a node steers a packet through an ordered list of instructions, called segments. Segments are identified through Segment Identifiers (SIDs). Segment Routing can be directly instantiated on the IPv6 data plane through the use of the Segment Routing Header defined in [RFC8754]. @@ -128,21 +128,21 @@ Several new sub-TLVs are defined to advertise various SRv6 Maximum SID Depths. The SRv6 End SID sub-TLV, the SRv6 End.X SID sub-TLV, and the SRv6 LAN End.X SID sub-TLV are used to advertise which SIDs are instantiated at a node and what Endpoint behavior is bound to each instantiated SID. This documents updates [RFC7370] by modifying an existing registry - Section 11.1.2. + (Section 11.1.2). 2. SRv6 Capabilities sub-TLV A node indicates that it supports the SR Segment Endpoint Node functionality as specified in [RFC8754] by advertising a new SRv6 Capabilities sub-TLV of the router capabilities TLV [RFC7981]. The SRv6 Capabilities sub-TLV may contain optional sub-sub-TLVs. No sub-sub-TLVs are currently defined. @@ -184,21 +184,21 @@ for Maximum SID Depths (MSD) of various types. Node MSDs are advertised in a sub-TLV of the Router Capabilities TLV [RFC7981]. Link MSDs are advertised in a sub-TLV of TLVs 22, 23, 141, 222, and 223. This document defines the relevant SRv6 MSDs and requests MSD type assignments in the MSD Types registry created by [RFC8491]. 4.1. Maximum Segments Left MSD Type - The Maximum Segments Left MSD Type specifies the maximum value of the + The Maximum Segments Left MSD Type signals the maximum value of the "Segments Left" field [RFC8754] in the SRH of a received packet before applying the Endpoint behavior associated with a SID. SRH Max Segments Left Type: 41 If no value is advertised the supported value is 0. 4.2. Maximum End Pop MSD Type The Maximum End Pop MSD Type signals the maximum number of SIDs in @@ -224,21 +224,21 @@ inserting any SRH header. A non-zero SRH Max H.encaps MSD indicates that the headend can insert an SRH up to the advertised value. 4.4. Maximum End D MSD Type The Maximum End D MSD Type specifies the maximum number of SIDs present in an SRH when performing decapsulation. These includes, but not limited to, End.DX6, End.DT4, End.DT46, End with USD, End.X with - USD as defined in [RFC8986]). + USD as defined in [RFC8986]. SRH Max End D Type: 45 If the advertised value is zero or no value is advertised then the router cannot apply any behavior that results in decapsulation and forwarding of the inner packet if the other IPv6 header contains an SRH. 5. SRv6 SIDs and Reachability @@ -255,28 +255,30 @@ SRv6 Locator TLV MUST be installed in the forwarding plane of receiving SRv6 capable routers when the associated topology/algorithm is supported by the receiving node. The processing of the prefix advertised in the SRv6 Locator TLV, the calculation of its reachability and the installation in the forwarding plane follows the process defined for the Prefix Reachability TLV 236 [RFC5308], or TLV 237 [RFC5120]. Locators associated with algorithm 0 and 1 (for all supported topologies) SHOULD be advertised in a Prefix Reachability TLV (236 or - 237) so that legacy routers (i.e., routers which do NOT support SRv6) + 237) so that legacy routers (i.e., routers which do not support SRv6) will install a forwarding entry for algorithm 0 and 1 SRv6 traffic. In cases where a locator advertisement is received in both a Prefix Reachability TLV and an SRv6 Locator TLV - (e.g. prefix, prefix- length, MTID all being equal and Algorithm being 0 in Locator TLV), - the Prefix Reachability advertisement MUST be preferred when - installing entries in the forwarding plane. This is to prevent + In case where the same prefix, with the same prefix-length, MTID, and + algorithm is received in both a Prefix Reachability TLV and an SRv6 + Locator TLV, the Prefix Reachability advertisement MUST be preferred + when installing entries in the forwarding plane. This is to prevent inconsistent forwarding entries between SRv6 capable and SRv6 incapable routers. Such preference of Prefix Reachability advertisement does not have any impact on the rest of the data advertised in the SRv6 Locator TLV. Locators associated with Flexible Algorithms (see Section 4 of [I-D.ietf-lsr-flex-algo]) SHOULD NOT be advertised in Prefix Reachability TLVs (236 or 237). Advertising the Flexible Algorithm locator in regular Prefix Reachability TLV (236 or 237) would make the forwarding for it to follow algo 0 path. @@ -811,22 +816,22 @@ Type: 25 Description: SRv6 Capabilities sub-TLV. Reference: This document (Section 2). This document requests the creation of a new IANA managed registry, under "IS-IS TLV Codepoints" registry - sub-sub-TLVs of the SRv6 Capability sub-TLV. The registration procedure is "Expert Review" as defined in [RFC8126]. Guidance for the Designated Experts is - provided in [RFC7370]. Suggested registry name is "sub-sub-TLVs for - SRv6 Capability sub-TLV". No sub-sub-TLVs are defined by this + provided in the [RFC7370]. Suggested registry name is "sub-sub-TLVs + for SRv6 Capability sub-TLV". No sub-sub-TLVs are defined by this document except for the reserved value. 0: Reserved 1-255: Unassigned 11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs This document makes the following registrations in the "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223 (Extended IS reachability, IS @@ -851,43 +856,43 @@ 43 y y y y y y 44 y y y y y y 11.4. MSD Types This document makes the following registrations in the IGP MSD-Types registry: Value Name Reference ------------------ - 41 SRH Max SL Section 4.1 - 42 SRH Max End Pop Section 4.2 - 44 SRH Max H.encaps Section 4.3 - 45 SRH Max End D Section 4.4 + 41 SRH Max SL [This Document] + 42 SRH Max End Pop [This Document] + 44 SRH Max H.encaps [This Document] + 45 SRH Max End D [This Document] 11.5. Sub-Sub-TLVs for SID Sub-TLVs This document requests a new IANA registry be created under the IS-IS TLV Codepoints Registry to control the assignment of sub-TLV types for the SID Sub-TLVs specified in this document - Section 7.2, Section 8.1, Section 8.2. The suggested name of the new registry is "sub-sub-TLVs for SRv6 End SID (5) (sub-TLV of TLVs 27, 135, 235, 236 - and 237) and SRv6 End.X SID (43)/SRv6 LAN End.X SID (44) (sub-TLVs of - TLVs 27, 135, 235, 236 and 237)". The registration procedure is - "Expert Review" as defined in [RFC8126]. Guidance for the Designated - Experts is provided in [RFC7370]The following assignments are made by - this document: + and 237) and SRv6 End.X SID (43)/SRv6 LAN End.X SID (44) (Sub-TLVs + for TLVs 22, 23, 25, 141, 222, and 223)". The registration procedure + is "Expert Review" as defined in [RFC8126]. Guidance for the + Designated Experts is provided in [RFC7370]. The following + assignments are made by this document: Type Description Encoding Reference --------------------------------------------------------- 0 Reserved - 1 SRv6 SID Structure Sub-Sub-TLV Section 9 + 1 SRv6 SID Structure Sub-Sub-TLV [This Document] 2-255 Unassigned Type 5 43 44 1 y y y 11.6. Prefix Attribute Flags Sub-TLV This document adds a new bit in the "Bit Values for Prefix Attribute Flags Sub-TLV" registry: