Segment Routing MPLS Interworking with LDP
RFC 8661
Document | Type | RFC - Proposed Standard (December 2019; No errata) | |
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Authors | Ahmed Bashandy , Clarence Filsfils , Stefano Previdi , Bruno Decraene , Stephane Litkowski | ||
Last updated | 2019-12-06 | ||
Replaces | draft-filsfils-spring-segment-routing-ldp-interop | ||
Stream | Internet Engineering Task Force (IETF) | ||
Formats | plain text html xml pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Rob Shakir | ||
Shepherd write-up | Show (last changed 2017-07-12) | ||
IESG | IESG state | RFC 8661 (Proposed Standard) | |
Action Holders |
(None)
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Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Alvaro Retana | ||
Send notices to | aretana.ietf@gmail.com, Rob Shakir <robjs@google.com> | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | No IANA Actions |
Internet Engineering Task Force (IETF) A. Bashandy, Ed. Request for Comments: 8661 Individual Category: Standards Track C. Filsfils, Ed. ISSN: 2070-1721 Cisco Systems, Inc. S. Previdi Huawei Technologies B. Decraene S. Litkowski Orange December 2019 Segment Routing MPLS Interworking with LDP Abstract A Segment Routing (SR) node steers a packet through a controlled set of instructions, called segments, by prepending the packet with an SR header. A segment can represent any instruction, topological or service based. SR allows enforcing a flow through any topological path while maintaining per-flow state only at the ingress node to the SR domain. The Segment Routing architecture can be directly applied to the MPLS data plane with no change in the forwarding plane. This document describes how Segment Routing MPLS operates in a network where LDP is deployed and in the case where SR-capable and non-SR-capable nodes coexist. 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/rfc8661. 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. SR-LDP Ships-in-the-Night Coexistence 2.1. MPLS2MPLS, MPLS2IP, and IP2MPLS Coexistence 3. SR and LDP Interworking 3.1. LDP to SR 3.1.1. LDP to SR Behavior 3.2. SR to LDP 3.2.1. Segment Routing Mapping Server (SRMS) 3.2.2. SR to LDP Behavior 3.2.3. Interoperability of Multiple SRMSes and Prefix-SID Advertisements 4. SR-LDP Interworking Use Cases 4.1. SR Protection of LDP-Based Traffic 4.2. Eliminating Targeted LDP Sessions 4.3. Guaranteed FRR Coverage 4.4. Inter-AS Option C, Carrier's Carrier 5. IANA Considerations 6. Manageability Considerations 6.1. SR and LDP Coexistence 6.2. Data-Plane Verification 7. Security Considerations 8. References 8.1. Normative References 8.2. Informative References Appendix A. Migration from LDP to SR Acknowledgements Contributors Authors' Addresses 1. Introduction Segment Routing, as described in [RFC8402], can be used on top of the MPLS data plane without any modification as described in [RFC8660]. Segment Routing control plane can coexist with current label distribution protocols such as LDP [RFC5036]. This document outlines the mechanisms through which SR interworks with LDP in cases where a mix of SR-capable and non-SR-capable routers coexist within the same network and more precisely in the same routing domain. Section 2 describes the coexistence of SR with other MPLS control- plane protocols. Section 3 documents the interworking between SR and LDP in the case of nonhomogeneous deployment. Section 4 describes how a partial SR deployment can be used to provide SR benefits to LDP-based traffic including a possible application of SR in the context of interdomain MPLS use cases. Appendix A documents a method to migrate from LDP to SR-based MPLS tunneling. Typically, an implementation will allow an operator to select (through configuration) which of the described modes of SR and LDP coexistence to use. 1.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",Show full document text