Operational management of Loop Free Alternates
draft-ietf-rtgwg-lfa-manageability-09

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Document Type Active Internet-Draft (rtgwg WG)
Last updated 2015-06-19
Replaces draft-litkowski-rtgwg-lfa-manageability
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Routing Area Working Group                             S. Litkowski, Ed.
Internet-Draft                                               B. Decraene
Intended status: Standards Track                                  Orange
Expires: December 21, 2015                                   C. Filsfils
                                                                 K. Raza
                                                           Cisco Systems
                                                            M. Horneffer
                                                        Deutsche Telekom
                                                               P. Sarkar
                                                        Juniper Networks
                                                           June 19, 2015

             Operational management of Loop Free Alternates
                 draft-ietf-rtgwg-lfa-manageability-09

Abstract

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

   This proposal is also applicable to remote LFA solution.

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 http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

Litkowski, et al.       Expires December 21, 2015               [Page 1]
Internet-Draft              LFA manageability                  June 2015

   This Internet-Draft will expire on December 21, 2015.

Copyright Notice

   Copyright (c) 2015 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
   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.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Operational issues with default LFA tie breakers  . . . . . .   4
     3.1.  Case 1: PE router protecting failures within core network   4
     3.2.  Case 2: PE router choosen to protect core failures while
           P router LFA exists . . . . . . . . . . . . . . . . . . .   5
     3.3.  Case 3: suboptimal P router alternate choice  . . . . . .   6
     3.4.  Case 4: IS-IS overload bit on LFA computing node  . . . .   7
   4.  Need for coverage monitoring  . . . . . . . . . . . . . . . .   8
   5.  Need for LFA activation granularity . . . . . . . . . . . . .   9
   6.  Configuration requirements  . . . . . . . . . . . . . . . . .   9
     6.1.  LFA enabling/disabling scope  . . . . . . . . . . . . . .   9
     6.2.  Policy based LFA selection  . . . . . . . . . . . . . . .  10
       6.2.1.  Connected vs remote alternates  . . . . . . . . . . .  11
       6.2.2.  Mandatory criteria  . . . . . . . . . . . . . . . . .  11
       6.2.3.  Enhanced criteria . . . . . . . . . . . . . . . . . .  12
       6.2.4.  Criteria evaluation . . . . . . . . . . . . . . . . .  12
       6.2.5.  Retrieving alternate path attributes  . . . . . . . .  16
       6.2.6.  ECMP LFAs . . . . . . . . . . . . . . . . . . . . . .  21
   7.  Operational aspects . . . . . . . . . . . . . . . . . . . . .  22
     7.1.  IS-IS overload bit on LFA computing node  . . . . . . . .  22
     7.2.  Manual triggering of FRR  . . . . . . . . . . . . . . . .  23
     7.3.  Required local information  . . . . . . . . . . . . . . .  24
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