Micro-loop prevention by introducing a local convergence delay
draft-ietf-rtgwg-uloop-delay-09

Document Type Active Internet-Draft (rtgwg WG)
Last updated 2017-11-12
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: May 16, 2018                                        C. Filsfils
                                                           Cisco Systems
                                                             P. Francois
                                                              Individual
                                                       November 12, 2017

     Micro-loop prevention by introducing a local convergence delay
                    draft-ietf-rtgwg-uloop-delay-09

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-step 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 is limited to the link down event in order to
   keep the mechanism simple.

   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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

Litkowski, et al.         Expires May 16, 2018                  [Page 1]
Internet-Draft                 uloop-delay                 November 2017

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 16, 2018.

Copyright Notice

   Copyright (c) 2017 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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Acronyms  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Transient forwarding loops side effects . . . . . . . . . . .   4
     3.1.  Fast reroute inefficiency . . . . . . . . . . . . . . . .   4
     3.2.  Network congestion  . . . . . . . . . . . . . . . . . . .   7
   4.  Overview of the solution  . . . . . . . . . . . . . . . . . .   7
   5.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  Regular IGP reaction  . . . . . . . . . . . . . . . . . .   8
     5.3.  Local events  . . . . . . . . . . . . . . . . . . . . . .   9
     5.4.  Local delay for link down . . . . . . . . . . . . . . . .  10
   6.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Applicable case: local loops  . . . . . . . . . . . . . .  10
     6.2.  Non applicable case: remote loops . . . . . . . . . . . .  11
   7.  Simulations . . . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  Deployment considerations . . . . . . . . . . . . . . . . . .  12
   9.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  Local link down . . . . . . . . . . . . . . . . . . . . .  14
     9.2.  Local and remote event  . . . . . . . . . . . . . . . . .  18
     9.3.  Aborting local delay  . . . . . . . . . . . . . . . . . .  19
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