Micro-loop avoidance using SPRING
draft-hegde-rtgwg-microloop-avoidance-using-spring-00

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Document Type Active Internet-Draft (individual)
Author Shraddha Hegde 
Last updated 2015-10-18
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Routing area                                                    S. Hegde
Internet-Draft                                                 P. Sarkar
Intended status: Standards Track                  Juniper Networks, Inc.
Expires: April 20, 2016                                 October 18, 2015

                   Micro-loop avoidance using SPRING
         draft-hegde-rtgwg-microloop-avoidance-using-spring-00

Abstract

   When there is a change in network topology either due to a link going
   down or due to a new link addition, all the nodes in the network need
   to get the complete view of the network and re-compute the routes.
   There will generally be a small time window when the forwarding state
   of each of the nodes is not synchronized.  This can result in
   transient loops in the network, leading to dropped traffic due to
   over-subscription of links.  Micro-looping is generally more harmful
   than simply dropping traffic on failed links, because it can cause
   control traffic to be dropped on an otherwise healthy link involved
   in micro-loop.  This can lead to cascading adjacency failures or
   network meltdown.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on April 20, 2016.

Hegde & Sarkar           Expires April 20, 2016                 [Page 1]
Internet-Draft      Microloop avoidance using SPRING        October 2015

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Procedures for Micro-loop prevention  . . . . . . . . . . . .   3
   3.  Detailed Solution based on SPRING . . . . . . . . . . . . . .   4
     3.1.  Link-down event . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Link-up event . . . . . . . . . . . . . . . . . . . . . .  10
     3.3.  Computation of nearest PLR  . . . . . . . . . . . . . . .  11
       3.3.1.  Link down event . . . . . . . . . . . . . . . . . . .  11
       3.3.2.  Node down event . . . . . . . . . . . . . . . . . . .  11
     3.4.  Handling multiple network events  . . . . . . . . . . . .  12
       3.4.1.  Handling SRLG failures  . . . . . . . . . . . . . . .  12
     3.5.  Handling ECMP . . . . . . . . . . . . . . . . . . . . . .  14
     3.6.  Recognizing same network event  . . . . . . . . . . . . .  14
     3.7.  Partial deployment Considerations . . . . . . . . . . . .  14
   4.  Protocol Procedures . . . . . . . . . . . . . . . . . . . . .  16
     4.1.  OSPF  . . . . . . . . . . . . . . . . . . . . . . . . . .  16
     4.2.  ISIS  . . . . . . . . . . . . . . . . . . . . . . . . . .  16
     4.3.  Elements of procedure . . . . . . . . . . . . . . . . . .  17
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  18
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  18
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   Micro-loops are transient loops that occur during the period of time
   when some nodes have become aware of a topology change and have
   changed their forwarding tables in response, but slow routers have
   not yet modified their forwarding tables.  This document provides
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