RIFT: Routing in Fat Trees
draft-ietf-rift-rift-03

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Last updated 2018-10-19
Replaces draft-przygienda-rift
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RIFT Working Group                                      The RIFT Authors
Internet-Draft      "Heaven is under our feet as well as over our heads"
Intended status: Standards Track                        October 19, 2018
Expires: April 22, 2019

                       RIFT: Routing in Fat Trees
                        draft-ietf-rift-rift-03

Abstract

   This document outlines a specialized, dynamic routing protocol for
   Clos and fat-tree network topologies.  The protocol (1) deals with
   fully automatied construction of fat-tree topologies based on
   detection of links, (2) minimizes the amount of routing state held at
   each level, (3) automatically prunes and load balances topology
   flooding exchanges over a sufficient subset of links, (4) supports
   automatic disaggregation of prefixes on link and node failures to
   prevent black-holing and suboptimal routing, (5) allows traffic
   steering and re-routing policies, (6) allows loop-free non-ECMP
   forwarding, (7) automatically re-balances traffic towards the spines
   based on bandwidth available and finally (8) provides mechanisms to
   synchronize a limited key-value data-store that can be used after
   protocol convergence to e.g.  bootstrap higher levels of
   functionality on nodes.

Status of This Memo

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Copyright Notice

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

The RIFT Authors         Expires April 22, 2019                 [Page 1]
Internet-Draft                    RIFT                      October 2018

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Table of Contents

   1.  Authors . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   6
   3.  Reference Frame . . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Topology  . . . . . . . . . . . . . . . . . . . . . . . .  10
   4.  Requirement Considerations  . . . . . . . . . . . . . . . . .  11
   5.  RIFT: Routing in Fat Trees  . . . . . . . . . . . . . . . . .  14
     5.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .  15
       5.1.1.  Properties  . . . . . . . . . . . . . . . . . . . . .  15
       5.1.2.  Generalized Topology View . . . . . . . . . . . . . .  15
       5.1.3.  Fallen Leaf Problem . . . . . . . . . . . . . . . . .  25
       5.1.4.  Discovering Fallen Leaves . . . . . . . . . . . . . .  27
       5.1.5.  Addressing the Fallen Leaves Problem  . . . . . . . .  28
     5.2.  Specification . . . . . . . . . . . . . . . . . . . . . .  29
       5.2.1.  Transport . . . . . . . . . . . . . . . . . . . . . .  29
       5.2.2.  Link (Neighbor) Discovery (LIE Exchange)  . . . . . .  30
       5.2.3.  Topology Exchange (TIE Exchange)  . . . . . . . . . .  32
         5.2.3.1.  Topology Information Elements . . . . . . . . . .  32
         5.2.3.2.  South- and Northbound Representation  . . . . . .  33
         5.2.3.3.  Flooding  . . . . . . . . . . . . . . . . . . . .  35
         5.2.3.4.  TIE Flooding Scopes . . . . . . . . . . . . . . .  36
         5.2.3.5.  Initial and Periodic Database Synchronization . .  38
         5.2.3.6.  Purging . . . . . . . . . . . . . . . . . . . . .  38
         5.2.3.7.  Southbound Default Route Origination  . . . . . .  39
         5.2.3.8.  Northbound TIE Flooding Reduction . . . . . . . .  40
       5.2.4.  Reachability Computation  . . . . . . . . . . . . . .  44
         5.2.4.1.  Northbound SPF  . . . . . . . . . . . . . . . . .  44
         5.2.4.2.  Southbound SPF  . . . . . . . . . . . . . . . . .  45
         5.2.4.3.  East-West Forwarding Within a Level . . . . . . .  45
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