Segment Routing with MPLS data plane
draft-ietf-spring-segment-routing-mpls-18
Network Working Group A. Bashandy, Ed.
Internet Draft Arrcus
Intended status: Standards Track C. Filsfils, Ed.
Expires: June 2019 S. Previdi,
Cisco Systems, Inc.
B. Decraene
S. Litkowski
Orange
R. Shakir
Google
December 9, 2018
Segment Routing with MPLS data plane
draft-ietf-spring-segment-routing-mpls-18
Abstract
Segment Routing (SR) leverages the source routing paradigm. A node
steers a packet through a controlled set of instructions, called
segments, by prepending the packet with an SR header. In the MPLS
dataplane, the SR header is instantiated through a label stack. This
document specifies the forwarding behavior to allow instantiating SR
over the MPLS dataplane.
Status of this Memo
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This Internet-Draft will expire on June 9, 2019.
Filsfils, et al. Expires June 9, 2019 [Page 1]
Internet-Draft Segment Routing with MPLS December 2018
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Table of Contents
1. Introduction...................................................3
1.1. Requirements Language.....................................4
2. MPLS Instantiation of Segment Routing..........................4
2.1. Multiple Forwarding Behaviors for the Same Prefix.........5
2.2. SID Representation in the MPLS Forwarding Plane...........5
2.3. Segment Routing Global Block and Local Block..............6
2.4. Mapping a SID Index to an MPLS label......................6
2.5. Incoming Label Collision..................................7
2.5.1. Tie-breaking Rules..................................10
2.5.2. Redistribution between Routing Protocol Instances...13
2.5.2.1. Illustration...................................13
2.5.2.2. Illustration 2.................................14
2.6. Effect of Incoming Label Collision on Outgoing Label
Programming...................................................14
2.7. PUSH, CONTINUE, and NEXT.................................14
2.7.1. PUSH................................................15
2.7.2. CONTINUE............................................15
2.7.3. NEXT................................................15
2.7.3.1. Mirror SID.....................................15
2.8. MPLS Label Downloaded to FIB for Global and Local SIDs...16
2.9. Active Segment...........................................16
2.10. Forwarding behavior for Global SIDs.....................16
2.10.1. Forwarding for PUSH and CONTINUE of Global SIDs....16
2.10.2. Forwarding for NEXT Operation for Global SIDs......18
2.11. Forwarding Behavior for Local SIDs......................18
2.11.1. Forwarding for PUSH Operation on Local SIDs........18
2.11.2. Forwarding for CONTINUE Operation for Local SIDs...19
2.11.3. Outgoing label for NEXT Operation for Local SIDs...19
3. IANA Considerations...........................................19
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