draft-ietf-lsr-isis-srv6-extensions-13.txt   draft-ietf-lsr-isis-srv6-extensions-14.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 14, 2021 Individual Expires: October 24, 2021 Individual
B. Decraene B. Decraene
Orange Orange
Z. Hu Z. Hu
Huawei Technologies Huawei Technologies
April 12, 2021 April 22, 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-13 draft-ietf-lsr-isis-srv6-extensions-14
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.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on October 14, 2021. This Internet-Draft will expire on October 24, 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.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . . . . 3 2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . . . . 4
3. Advertising Supported Algorithms . . . . . . . . . . . . . . 4 3. Advertising Supported Algorithms . . . . . . . . . . . . . . 4
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 . . . . . . . . . . . . . . . . . 6
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 . . . . . . . . . . . . . . . . . 9
7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10 7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10
8. Advertising SRv6 Adjacency SIDs . . . . . . . . . . . . . . . 12 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 . . . . . . . . . . . . . . . 14 8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 14
9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 16 9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 16
10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 17 10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 17
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 17 11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 17
11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 18 11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 18
11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 18 11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 18
11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 19 11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 19
11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 19 11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 19
11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 20 11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 20
11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 20 11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 20
11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 21 11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 21
12. Security Considerations . . . . . . . . . . . . . . . . . . . 21 11.7. ISIS SRv6 Capabilities sub-TLV Flags Registry . . . . . 21
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 11.8. ISIS SRv6 Locator TLV Flags Registry . . . . . . . . . . 21
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 11.9. ISIS SRv6 End SID sub-TLV Flags Registry . . . . . . . . 22
14.1. Normative References . . . . . . . . . . . . . . . . . . 22 11.10. ISIS SRv6 End.X SID and LAN End.X SID sub-TLVs Flags
14.2. Informative References . . . . . . . . . . . . . . . . . 25 Registry . . . . . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 12. Security Considerations . . . . . . . . . . . . . . . . . . . 23
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 23
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
14.1. Normative References . . . . . . . . . . . . . . . . . . 24
14.2. Informative References . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
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].
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Flags: 1 octet. The following flags are defined Flags: 1 octet. The following flags are defined
0 0
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|D| Reserved | |D| Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
where: where:
D bit: Same as described in section 4.1. of [RFC5305]. D-flag: Same as described in section 4.1. of [RFC5305].
The remaining bits are reserved for future use. They MUST be The remaining bits are reserved for future use. They MUST be
set to zero on transmission and MUST be ignored on receipt. set to zero on transmission and MUST be ignored on receipt.
Algorithm: 1 octet. As defined in [RFC8665]. Algorithm: 1 octet. As defined in [RFC8665].
Loc-Size: 1 octet. Number of bits in the SRv6 Locator field. Loc-Size: 1 octet. Number of bits in the SRv6 Locator field.
MUST be from the range (1 - 128). The TLV MUST be ignored if MUST be from the range (1 - 128). The TLV MUST be ignored if
the Loc-Size is outside of this range. the Loc-Size is outside of this range.
Locator: 1-16 octets. This field encodes the advertised SRv6 Locator: 1-16 octets. This field encodes the advertised SRv6
Locator. The Locator is encoded in the minimal number of Locator. The Locator is encoded in the minimal number of
octets for the given number of bits. Trailing bits MUST be set octets for the given number of bits. Trailing bits MUST be set
to zero and ignored when received. to zero and ignored when received.
Sub-TLV-length: 1 octet. Number of octets used by sub-TLVs Sub-TLV-length: 1 octet. Number of octets used by sub-TLVs
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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:
Bit #: 4 Bit #: 4
Description: Anycast Flag (A-flag) Description: Anycast Flag (A-flag)
Reference: This document (Section 6). Reference: This document (Section 6).
11.7. ISIS SRv6 Capabilities sub-TLV Flags Registry
This document requests a new IANA registry be created under the IS-IS
TLV Codepoints Registry to control the assignment of bits in the
Flags field of the ISIS SRv6 Capabilities sub-TLV specified in this
document (Section 2). The suggested name of the new registry is
"ISIS SRv6 Capabilities sub-TLV Flags". 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:
Bit #: 1
Description: O-flag
Reference: This document (Section 2).
11.8. ISIS SRv6 Locator TLV Flags Registry
This document requests a new IANA registry be created under the IS-IS
TLV Codepoints Registry to control the assignment of bits in the
Flags field of the ISIS SRv6 SRv6 Locator TLV specified in this
document (Section 7.1). The suggested name of the new registry is
"ISIS SRv6 Locator TLV Flags". 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:
Bit #: 0
Description: D-flag
Reference: This document (Section 7.1).
11.9. ISIS SRv6 End SID sub-TLV Flags Registry
This document requests a new IANA registry be created under the IS-IS
TLV Codepoints Registry to control the assignment of bits in the
Flags field of the ISIS SRv6 End SID sub-TLV specified in this
document (Section 7.2). The suggested name of the new registry is
"ISIS SRv6 End SID sub-TLV Flags". The registration procedure is
"Expert Review" as defined in [RFC8126]. Guidance for the Designated
Experts is provided in [RFC7370]. No assignments are made by this
document.
11.10. ISIS SRv6 End.X SID and LAN End.X SID sub-TLVs Flags Registry
This document requests a new IANA registry be created under the IS-IS
TLV Codepoints Registry to control the assignment of bits in the
Flags field of the ISIS SRv6 End.X SID and LAN End.X SID sub-TLVs
(Section 8.1 and Section 8.2). The suggested name of the new
registry is "ISIS SRv6 End.X SID and LAN End.X SID sub-TLVs Flags".
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:
Bit #: 0
Description: B-flag
Reference: This document (Section 8.1).
Bit #: 1
Description: S-flag
Reference: This document (Section 8.1).
Bit #: 2
Description: P-flag
Reference: This document (Section 8.1).
12. Security Considerations 12. Security Considerations
Security concerns for IS-IS are addressed in [ISO10589], [RFC5304], Security concerns for IS-IS are addressed in [ISO10589], [RFC5304],
and [RFC5310]. While IS-IS is deployed under a single administrative and [RFC5310]. While IS-IS is deployed under a single administrative
domain, there can be deployments where potential attackers have domain, there can be deployments where potential attackers have
access to one or more networks in the IS-IS routing domain. In these access to one or more networks in the IS-IS routing domain. In these
deployments, the stronger authentication mechanisms defined in the deployments, the stronger authentication mechanisms defined in the
aforementioned documents SHOULD be used. aforementioned documents SHOULD be used.
This document describes the IS-IS extensions required to support This document describes the IS-IS extensions required to support
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