Operational management of Loop Free Alternates
draft-litkowski-rtgwg-lfa-manageability-00

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Last updated 2012-10-15
Replaced by RFC 7916, RFC 7916
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Routing Area Working Group                                  S. Litkowski
Internet-Draft                                               B. Decraene
Intended status: Standards Track                                  Orange
Expires: April 18, 2013                                      C. Filsfils
                                                                 K. Raza
                                                           Cisco Systems
                                                        October 15, 2012

             Operational management of Loop Free Alternates
               draft-litkowski-rtgwg-lfa-manageability-00

Abstract

   Loop Free Alternates (LFA), as defined in RFC 5286 is an IP Fast
   ReRoute (IP FRR) mechanism enabling traffic protection for IP
   traffic.  Following first deployment experience, this document
   provides operational feedback on LFA, highlights some limitations and
   proposes a set of refinements to address those limitations.

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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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 18, 2013.

Copyright Notice

   Copyright (c) 2012 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
   (http://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
   to this document.  Code Components extracted from this document must

Litkowski, et al.        Expires April 18, 2013                 [Page 1]
Internet-Draft              LFA manageability               October 2012

   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Operational issues with default LFA tie breakers . . . . . . .  3
     2.1.  Case 1: Edge router protecting core failures . . . . . . .  3
     2.2.  Case 2: Edge router choosen to protect core failures
           while core LFA exists  . . . . . . . . . . . . . . . . . .  5
     2.3.  Case 3: suboptimal core alternate choice . . . . . . . . .  6
   3.  Configuration aspects  . . . . . . . . . . . . . . . . . . . .  6
     3.1.  LFA activation . . . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Policy based LFA selection . . . . . . . . . . . . . . . .  7
       3.2.1.  Mandatory criteria . . . . . . . . . . . . . . . . . .  8
       3.2.2.  Enhanced criteria  . . . . . . . . . . . . . . . . . .  8
   4.  Operational aspects  . . . . . . . . . . . . . . . . . . . . . 12
     4.1.  Controlling LFA computation  . . . . . . . . . . . . . . . 12
     4.2.  Manual triggering of FRR . . . . . . . . . . . . . . . . . 13
     4.3.  Required local information . . . . . . . . . . . . . . . . 13
     4.4.  Coverage followup  . . . . . . . . . . . . . . . . . . . . 13
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 14
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15

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1.  Introduction

   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].

   This document is being discussed on the rtgwg@ietf.org mailing list.

2.  Operational issues with default LFA tie breakers

   [RFC5286] introduces the notion of tie breakers when selecting the
   LFA among multiple candidate alternate next-hops.  Most
   implementations are using the following algorithm :

   o  Prefer node protection alternate over link protection alternate.
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