Entropy label for SPRING tunnels
draft-ietf-mpls-spring-entropy-label-12

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Network Working Group                                            S. Kini
Internet-Draft
Intended status: Standards Track                             K. Kompella
Expires: January 17, 2019                                        Juniper
                                                            S. Sivabalan
                                                                   Cisco
                                                            S. Litkowski
                                                                  Orange
                                                               R. Shakir
                                                                  Google
                                                             J. Tantsura
                                                           July 16, 2018

                    Entropy label for SPRING tunnels
                draft-ietf-mpls-spring-entropy-label-12

Abstract

   Segment Routing (SR) leverages the source routing paradigm.  A node
   steers a packet through an ordered list of instructions, called
   segments.  Segment Routing can be applied to the Multi Protocol Label
   Switching (MPLS) data plane.  Entropy label (EL) is a technique used
   in MPLS to improve load-balancing.  This document examines and
   describes how ELs are to be applied to Segment Routing MPLS.

Status of This Memo

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   This Internet-Draft will expire on January 17, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Kini, et al.            Expires January 17, 2019                [Page 1]
Internet-Draft      Entropy Labels for SPRING tunnels          July 2018

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Abbreviations and Terminology . . . . . . . . . . . . . . . .   4
   3.  Use-case requiring multipath load-balancing . . . . . . . . .   5
   4.  Entropy Readable Label Depth  . . . . . . . . . . . . . . . .   6
   5.  Maximum SID Depth . . . . . . . . . . . . . . . . . . . . . .   8
   6.  LSP stitching using the Binding-SID . . . . . . . . . . . . .  10
   7.  Insertion of entropy labels for SPRING path . . . . . . . . .  11
     7.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .  11
       7.1.1.  Example 1 where the ingress node has a sufficient MSD  12
       7.1.2.  Example 2 where the ingress node does not have a
               sufficient MSD  . . . . . . . . . . . . . . . . . . .  13
     7.2.  Considerations for the placement of entropy labels  . . .  14
       7.2.1.  ERLD value  . . . . . . . . . . . . . . . . . . . . .  15
       7.2.2.  Segment type  . . . . . . . . . . . . . . . . . . . .  16
         7.2.2.1.  Node-SID  . . . . . . . . . . . . . . . . . . . .  16
         7.2.2.2.  Adjacency-set SID . . . . . . . . . . . . . . . .  17
         7.2.2.3.  Adjacency-SID representing a single IP link . . .  17
         7.2.2.4.  Adjacency-SID representing a single link within
                   an L2 bundle  . . . . . . . . . . . . . . . . . .  17
         7.2.2.5.  Adjacency-SID representing an L2 bundle . . . . .  17
       7.2.3.  Maximizing number of LSRs that will load-balance  . .  18
       7.2.4.  Preference for a part of the path . . . . . . . . . .  18
       7.2.5.  Combining criteria  . . . . . . . . . . . . . . . . .  18
   8.  A simple example algorithm  . . . . . . . . . . . . . . . . .  18
   9.  Deployment Considerations . . . . . . . . . . . . . . . . . .  19
   10. Options considered  . . . . . . . . . . . . . . . . . . . . .  20