draft-ietf-lsr-isis-srv6-extensions-12.txt   draft-ietf-lsr-isis-srv6-extensions-13.txt 
Networking Working Group P. Psenak, Ed. Networking Working Group P. Psenak, Ed.
Internet-Draft C. Filsfils Internet-Draft C. Filsfils
Updates: 7370 (if approved) Cisco Systems Updates: 7370 (if approved) Cisco Systems
Intended status: Standards Track A. Bashandy Intended status: Standards Track A. Bashandy
Expires: October 10, 2021 Individual Expires: October 14, 2021 Individual
B. Decraene B. Decraene
Orange Orange
Z. Hu Z. Hu
Huawei Technologies Huawei Technologies
April 8, 2021 April 12, 2021
IS-IS Extension to Support Segment Routing over IPv6 Dataplane 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 Abstract
The Segment Routing (SR) allows for a flexible definition of end-to- The Segment Routing (SR) allows for a flexible definition of end-to-
end paths by encoding paths as sequences of topological sub-paths, end paths by encoding paths as sequences of topological sub-paths,
called "segments". Segment routing architecture can be implemented called "segments". Segment routing architecture can be implemented
over an MPLS data plane as well as an IPv6 data plane. This document over an MPLS data plane as well as an IPv6 data plane. This document
describes the IS-IS extensions required to support Segment Routing describes the IS-IS extensions required to support Segment Routing
over an IPv6 data plane. 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 Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Status of This Memo Status of This Memo
skipping to change at page 2, line 4 skipping to change at page 2, line 4
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." 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 Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 36 skipping to change at page 2, line 36
4. Advertising Maximum SRv6 SID Depths . . . . . . . . . . . . . 4 4. Advertising Maximum SRv6 SID Depths . . . . . . . . . . . . . 4
4.1. Maximum Segments Left MSD Type . . . . . . . . . . . . . 5 4.1. Maximum Segments Left MSD Type . . . . . . . . . . . . . 5
4.2. Maximum End Pop MSD Type . . . . . . . . . . . . . . . . 5 4.2. Maximum End Pop MSD Type . . . . . . . . . . . . . . . . 5
4.3. Maximum H.Encaps MSD Type . . . . . . . . . . . . . . . . 5 4.3. Maximum H.Encaps MSD Type . . . . . . . . . . . . . . . . 5
4.4. Maximum End D MSD Type . . . . . . . . . . . . . . . . . 5 4.4. Maximum End D MSD Type . . . . . . . . . . . . . . . . . 5
5. SRv6 SIDs and Reachability . . . . . . . . . . . . . . . . . 6 5. SRv6 SIDs and Reachability . . . . . . . . . . . . . . . . . 6
6. Advertising Anycast Property . . . . . . . . . . . . . . . . 7 6. Advertising Anycast Property . . . . . . . . . . . . . . . . 7
7. Advertising Locators and End SIDs . . . . . . . . . . . . . . 8 7. Advertising Locators and End SIDs . . . . . . . . . . . . . . 8
7.1. SRv6 Locator TLV Format . . . . . . . . . . . . . . . . . 8 7.1. SRv6 Locator TLV Format . . . . . . . . . . . . . . . . . 8
7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10 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 8.1. SRv6 End.X SID sub-TLV . . . . . . . . . . . . . . . . . 12
8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 13 8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 14
9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 15 9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 16
10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 16 10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 17
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 16 11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 17
11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 17 11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 18
11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 17 11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 18
11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 18 11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 19
11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 18 11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 19
11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 19 11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 20
11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 19 11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 20
11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 20 11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 21
12. Security Considerations . . . . . . . . . . . . . . . . . . . 20 12. Security Considerations . . . . . . . . . . . . . . . . . . . 21
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
14.1. Normative References . . . . . . . . . . . . . . . . . . 21 14.1. Normative References . . . . . . . . . . . . . . . . . . 22
14.2. Informative References . . . . . . . . . . . . . . . . . 24 14.2. Informative References . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
With Segment Routing (SR) [RFC8402], a node steers a packet through With Segment Routing (SR) [RFC8402], a node steers a packet through
an ordered list of instructions, called segments. an ordered list of instructions, called segments.
Segments are identified through Segment Identifiers (SIDs). Segments are identified through Segment Identifiers (SIDs).
Segment Routing can be directly instantiated on the IPv6 data plane Segment Routing can be directly instantiated on the IPv6 data plane
through the use of the Segment Routing Header defined in [RFC8754]. through the use of the Segment Routing Header defined in [RFC8754].
skipping to change at page 3, line 45 skipping to change at page 3, line 45
Several new sub-TLVs are defined to advertise various SRv6 Maximum Several new sub-TLVs are defined to advertise various SRv6 Maximum
SID Depths. SID Depths.
The SRv6 End SID sub-TLV, the SRv6 End.X SID sub-TLV, and the SRv6 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 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 at a node and what Endpoint behavior is bound to each
instantiated SID. instantiated SID.
This documents updates [RFC7370] by modifying an existing registry This documents updates [RFC7370] by modifying an existing registry
Section 11.1.2. (Section 11.1.2).
2. SRv6 Capabilities sub-TLV 2. SRv6 Capabilities sub-TLV
A node indicates that it supports the SR Segment Endpoint Node A node indicates that it supports the SR Segment Endpoint Node
functionality as specified in [RFC8754] by advertising a new SRv6 functionality as specified in [RFC8754] by advertising a new SRv6
Capabilities sub-TLV of the router capabilities TLV [RFC7981]. Capabilities sub-TLV of the router capabilities TLV [RFC7981].
The SRv6 Capabilities sub-TLV may contain optional sub-sub-TLVs. No The SRv6 Capabilities sub-TLV may contain optional sub-sub-TLVs. No
sub-sub-TLVs are currently defined. sub-sub-TLVs are currently defined.
skipping to change at page 5, line 7 skipping to change at page 5, line 7
for Maximum SID Depths (MSD) of various types. Node MSDs are for Maximum SID Depths (MSD) of various types. Node MSDs are
advertised in a sub-TLV of the Router Capabilities TLV [RFC7981]. 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 Link MSDs are advertised in a sub-TLV of TLVs 22, 23, 141, 222, and
223. 223.
This document defines the relevant SRv6 MSDs and requests MSD type This document defines the relevant SRv6 MSDs and requests MSD type
assignments in the MSD Types registry created by [RFC8491]. assignments in the MSD Types registry created by [RFC8491].
4.1. Maximum Segments Left MSD Type 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 "Segments Left" field [RFC8754] in the SRH of a received packet
before applying the Endpoint behavior associated with a SID. before applying the Endpoint behavior associated with a SID.
SRH Max Segments Left Type: 41 SRH Max Segments Left Type: 41
If no value is advertised the supported value is 0. If no value is advertised the supported value is 0.
4.2. Maximum End Pop MSD Type 4.2. Maximum End Pop MSD Type
The Maximum End Pop MSD Type signals the maximum number of SIDs in The Maximum End Pop MSD Type signals the maximum number of SIDs in
skipping to change at page 5, line 47 skipping to change at page 5, line 47
inserting any SRH header. inserting any SRH header.
A non-zero SRH Max H.encaps MSD indicates that the headend can insert A non-zero SRH Max H.encaps MSD indicates that the headend can insert
an SRH up to the advertised value. an SRH up to the advertised value.
4.4. Maximum End D MSD Type 4.4. Maximum End D MSD Type
The Maximum End D MSD Type specifies the maximum number of SIDs The Maximum End D MSD Type specifies the maximum number of SIDs
present in an SRH when performing decapsulation. These includes, but 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 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 SRH Max End D Type: 45
If the advertised value is zero or no value is advertised If the advertised value is zero or no value is advertised
then the router cannot apply any behavior that results in then the router cannot apply any behavior that results in
decapsulation and forwarding of the inner packet if the decapsulation and forwarding of the inner packet if the
other IPv6 header contains an SRH. other IPv6 header contains an SRH.
5. SRv6 SIDs and Reachability 5. SRv6 SIDs and Reachability
skipping to change at page 6, line 34 skipping to change at page 6, line 34
SRv6 Locator TLV MUST be installed in the forwarding plane of SRv6 Locator TLV MUST be installed in the forwarding plane of
receiving SRv6 capable routers when the associated topology/algorithm receiving SRv6 capable routers when the associated topology/algorithm
is supported by the receiving node. The processing of the prefix is supported by the receiving node. The processing of the prefix
advertised in the SRv6 Locator TLV, the calculation of its advertised in the SRv6 Locator TLV, the calculation of its
reachability and the installation in the forwarding plane follows the reachability and the installation in the forwarding plane follows the
process defined for the Prefix Reachability TLV 236 [RFC5308], or TLV process defined for the Prefix Reachability TLV 236 [RFC5308], or TLV
237 [RFC5120]. 237 [RFC5120].
Locators associated with algorithm 0 and 1 (for all supported Locators associated with algorithm 0 and 1 (for all supported
topologies) SHOULD be advertised in a Prefix Reachability TLV (236 or 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. will install a forwarding entry for algorithm 0 and 1 SRv6 traffic.
In cases where a locator advertisement is received in both a Prefix In cases where a locator advertisement is received in both a Prefix
Reachability TLV and an SRv6 Locator TLV - (e.g. prefix, prefix- Reachability TLV and an SRv6 Locator TLV - (e.g. prefix, prefix-
length, MTID all being equal and Algorithm being 0 in Locator TLV), length, MTID all being equal and Algorithm being 0 in Locator TLV),
the Prefix Reachability advertisement MUST be preferred when In case where the same prefix, with the same prefix-length, MTID, and
installing entries in the forwarding plane. This is to prevent 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 inconsistent forwarding entries between SRv6 capable and SRv6
incapable routers. Such preference of Prefix Reachability incapable routers. Such preference of Prefix Reachability
advertisement does not have any impact on the rest of the data advertisement does not have any impact on the rest of the data
advertised in the SRv6 Locator TLV. advertised in the SRv6 Locator TLV.
Locators associated with Flexible Algorithms (see Section 4 of Locators associated with Flexible Algorithms (see Section 4 of
[I-D.ietf-lsr-flex-algo]) SHOULD NOT be advertised in Prefix [I-D.ietf-lsr-flex-algo]) SHOULD NOT be advertised in Prefix
Reachability TLVs (236 or 237). Advertising the Flexible Algorithm Reachability TLVs (236 or 237). Advertising the Flexible Algorithm
locator in regular Prefix Reachability TLV (236 or 237) would make locator in regular Prefix Reachability TLV (236 or 237) would make
the forwarding for it to follow algo 0 path. the forwarding for it to follow algo 0 path.
skipping to change at page 18, line 32 skipping to change at page 19, line 32
Type: 25 Type: 25
Description: SRv6 Capabilities sub-TLV. Description: SRv6 Capabilities sub-TLV.
Reference: This document (Section 2). Reference: This document (Section 2).
This document requests the creation of a new IANA managed registry, This document requests the creation of a new IANA managed registry,
under "IS-IS TLV Codepoints" registry - sub-sub-TLVs of the SRv6 under "IS-IS TLV Codepoints" registry - sub-sub-TLVs of the SRv6
Capability sub-TLV. The registration procedure is "Expert Review" as Capability sub-TLV. The registration procedure is "Expert Review" as
defined in [RFC8126]. Guidance for the Designated Experts is defined in [RFC8126]. Guidance for the Designated Experts is
provided in [RFC7370]. Suggested registry name is "sub-sub-TLVs for provided in the [RFC7370]. Suggested registry name is "sub-sub-TLVs
SRv6 Capability sub-TLV". No sub-sub-TLVs are defined by this for SRv6 Capability sub-TLV". No sub-sub-TLVs are defined by this
document except for the reserved value. document except for the reserved value.
0: Reserved 0: Reserved
1-255: Unassigned 1-255: Unassigned
11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs 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 This document makes the following registrations in the "Sub-TLVs for
TLVs 22, 23, 25, 141, 222, and 223 (Extended IS reachability, IS TLVs 22, 23, 25, 141, 222, and 223 (Extended IS reachability, IS
skipping to change at page 19, line 23 skipping to change at page 20, line 23
43 y y y y y y 43 y y y y y y
44 y y y y y y 44 y y y y y y
11.4. MSD Types 11.4. MSD Types
This document makes the following registrations in the IGP MSD-Types This document makes the following registrations in the IGP MSD-Types
registry: registry:
Value Name Reference Value Name Reference
------------------ ------------------
41 SRH Max SL Section 4.1 41 SRH Max SL [This Document]
42 SRH Max End Pop Section 4.2 42 SRH Max End Pop [This Document]
44 SRH Max H.encaps Section 4.3 44 SRH Max H.encaps [This Document]
45 SRH Max End D Section 4.4 45 SRH Max End D [This Document]
11.5. Sub-Sub-TLVs for SID Sub-TLVs 11.5. Sub-Sub-TLVs for SID Sub-TLVs
This document requests a new IANA registry be created under the IS-IS This document requests a new IANA registry be created under the IS-IS
TLV Codepoints Registry to control the assignment of sub-TLV types TLV Codepoints Registry to control the assignment of sub-TLV types
for the SID Sub-TLVs specified in this document - Section 7.2, 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 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 "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 and 237) and SRv6 End.X SID (43)/SRv6 LAN End.X SID (44) (Sub-TLVs
TLVs 27, 135, 235, 236 and 237)". The registration procedure is for TLVs 22, 23, 25, 141, 222, and 223)". The registration procedure
"Expert Review" as defined in [RFC8126]. Guidance for the Designated is "Expert Review" as defined in [RFC8126]. Guidance for the
Experts is provided in [RFC7370]The following assignments are made by Designated Experts is provided in [RFC7370]. The following
this document: assignments are made by this document:
Type Description Encoding Type Description Encoding
Reference Reference
--------------------------------------------------------- ---------------------------------------------------------
0 Reserved 0 Reserved
1 SRv6 SID Structure Sub-Sub-TLV Section 9 1 SRv6 SID Structure Sub-Sub-TLV [This Document]
2-255 Unassigned 2-255 Unassigned
Type 5 43 44 Type 5 43 44
1 y y y 1 y y y
11.6. Prefix Attribute Flags Sub-TLV 11.6. Prefix Attribute Flags Sub-TLV
This document adds a new bit in the "Bit Values for Prefix Attribute This document adds a new bit in the "Bit Values for Prefix Attribute
Flags Sub-TLV" registry: Flags Sub-TLV" registry:
 End of changes. 16 change blocks. 
42 lines changed or deleted 44 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/