Entropy label for SPRING tunnels
draft-ietf-mpls-spring-entropy-label-07

Document Type Active Internet-Draft (mpls WG)
Last updated 2017-10-17
Replaces draft-kini-mpls-spring-entropy-label
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Network Working Group                                            S. Kini
Internet-Draft
Intended status: Informational                               K. Kompella
Expires: April 20, 2018                                          Juniper
                                                            S. Sivabalan
                                                                   Cisco
                                                            S. Litkowski
                                                                  Orange
                                                               R. Shakir
                                                                  Google
                                                             J. Tantsura
                                                        October 17, 2017

                    Entropy label for SPRING tunnels
                draft-ietf-mpls-spring-entropy-label-07

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 when applied
   to the MPLS dataplane.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on April 20, 2018.

Kini, et al.             Expires April 20, 2018                 [Page 1]
Internet-Draft      Entropy Labels for SPRING tunnels       October 2017

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   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

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