IS-IS Extensions for Segment Routing
RFC 8667
Internet Engineering Task Force (IETF) S. Previdi, Ed.
Request for Comments: 8667 Huawei Technologies
Category: Standards Track L. Ginsberg, Ed.
ISSN: 2070-1721 C. Filsfils
Cisco Systems, Inc.
A. Bashandy
Arrcus
H. Gredler
RtBrick Inc.
B. Decraene
Orange
December 2019
IS-IS Extensions for Segment Routing
Abstract
Segment Routing (SR) allows for a flexible definition of end-to-end
paths within IGP topologies by encoding paths as sequences of
topological sub-paths, called "segments". These segments are
advertised by the link-state routing protocols (IS-IS and OSPF).
This document describes the IS-IS extensions that need to be
introduced for Segment Routing operating on an MPLS data plane.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8667.
Copyright Notice
Copyright (c) 2019 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
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction
1.1. Requirements Language
2. Segment Routing Identifiers
2.1. Prefix Segment Identifier (Prefix-SID) Sub-TLV
2.1.1. Flags
2.1.2. Prefix-SID Propagation
2.2. Adjacency Segment Identifier
2.2.1. Adjacency Segment Identifier (Adj-SID) Sub-TLV
2.2.2. Adjacency Segment Identifier (LAN-Adj-SID) Sub-TLV
2.3. SID/Label Sub-TLV
2.4. SID/Label Binding TLV
2.4.1. Flags
2.4.2. Range
2.4.3. Prefix Length, Prefix
2.4.4. Mapping Server Prefix-SID
2.4.5. SID/Label Sub-TLV
2.4.6. Example Encodings
2.5. Multi-Topology SID/Label Binding TLV
3. Router Capabilities
3.1. SR-Capabilities Sub-TLV
3.2. SR-Algorithm Sub-TLV
3.3. SR Local Block Sub-TLV
3.4. SRMS Preference Sub-TLV
4. IANA Considerations
4.1. Sub-TLVs for Types 22, 23, 25, 141, 222, and 223
4.2. Sub-TLVs for Types 135, 235, 236, and 237
4.3. Sub-TLVs for Type 242
4.4. New TLV Codepoint and Sub-TLV Registry
5. Security Considerations
6. References
6.1. Normative References
6.2. Informative References
Acknowledgements
Contributors
Authors' Addresses
1. Introduction
Segment Routing (SR) allows for a flexible definition of end-to-end
paths within IGP topologies by encoding paths as sequences of
topological sub-paths, called "segments". These segments are
advertised by the link-state routing protocols (IS-IS and OSPF).
Prefix segments represent an ECMP-aware shortest path to a prefix (or
a node), as per the state of the IGP topology. Adjacency segments
represent a hop over a specific adjacency between two nodes in the
IGP. A prefix segment is typically a multi-hop path while an
adjacency segment, in most of the cases, is a one-hop path. SR's
control plane can be applied to both IPv6 and MPLS data planes and
does not require any additional signaling (other than the regular
IGP). For example, when used in MPLS networks, SR paths do not
require any LDP or RSVP-TE signaling. Still, SR can interoperate in
the presence of Label Switched Paths (LSPs) established with RSVP or
LDP.
There are additional segment types, e.g., the Binding SID as defined
in [RFC8402]. This document also defines an advertisement for one
Show full document text