Micro-loop prevention by introducing a local convergence delay
draft-ietf-rtgwg-uloop-delay-03

Document Type Active Internet-Draft (rtgwg WG)
Last updated 2016-11-29
Replaces draft-litkowski-rtgwg-uloop-delay
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Routing Area Working Group                                  S. Litkowski
Internet-Draft                                               B. Decraene
Intended status: Standards Track                                  Orange
Expires: June 2, 2017                                        C. Filsfils
                                                             P. Francois
                                                           Cisco Systems
                                                       November 29, 2016

     Micro-loop prevention by introducing a local convergence delay
                    draft-ietf-rtgwg-uloop-delay-03

Abstract

   This document describes a mechanism for link-state routing protocols
   to prevent local transient forwarding loops in case of link failure.
   This mechanism proposes a two-steps convergence by introducing a
   delay between the convergence of the node adjacent to the topology
   change and the network wide convergence.

   As this mechanism delays the IGP convergence it may only be used for
   planned maintenance or when fast reroute protects the traffic between
   the link failure time and the IGP convergence.

   The proposed mechanism will be limited to the link down event in
   order to keep simplicity.

   Simulations using real network topologies have been performed and
   show that local loops are a significant portion (>50%) of the total
   forwarding loops.

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 [RFC2119].

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

Litkowski, et al.         Expires June 2, 2017                  [Page 1]
Internet-Draft                 uloop-delay                 November 2016

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   This Internet-Draft will expire on June 2, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Transient forwarding loops side effects . . . . . . . . . . .   3
     2.1.  Fast reroute inefficiency . . . . . . . . . . . . . . . .   4
     2.2.  Network congestion  . . . . . . . . . . . . . . . . . . .   6
   3.  Overview of the solution  . . . . . . . . . . . . . . . . . .   7
   4.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Current IGP reactions . . . . . . . . . . . . . . . . . .   7
     4.3.  Local events  . . . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Local delay for link down . . . . . . . . . . . . . . . .   9
   5.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Applicable case: local loops  . . . . . . . . . . . . . .   9
     5.2.  Non applicable case: remote loops . . . . . . . . . . . .  10
   6.  Simulations . . . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Deployment considerations . . . . . . . . . . . . . . . . . .  11
   8.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  Local link down . . . . . . . . . . . . . . . . . . . . .  12
     8.2.  Local and remote event  . . . . . . . . . . . . . . . . .  15
     8.3.  Aborting local delay  . . . . . . . . . . . . . . . . . .  17
   9.  Comparison with other solutions . . . . . . . . . . . . . . .  19
     9.1.  PLSN  . . . . . . . . . . . . . . . . . . . . . . . . . .  19
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