Best Practices for Advertisement of Multiple Paths in IBGP
draft-ietf-idr-add-paths-guidelines-02

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Document Type Active Internet-Draft (idr WG)
Last updated 2011-11-25 (latest revision 2011-05-26)
Replaces draft-uttaro-idr-add-paths-guidelines
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Network Working Group                                         J. Uttaro
Internet Draft                                                     AT&T
Intended status: Standards Track                    V. Van den Schrieck
Nov 25, 2011                                                  UCLouvain
Expires: May 25, 2012                                       P. Francois
                                                         IMDEA Networks
                                                            R. Fragassi
                                                             A. Simpson
                                                         Alcatel-Lucent
                                                           P. Mohapatra
                                                          Cisco Systems

        Best Practices for Advertisement of Multiple Paths in IBGP
                draft-ietf-idr-add-paths-guidelines-02.txt

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Uttaro, et al            Expires May 25, 2012                  [Page 1]
Internet-Draft  draft-ietf-idr-add-paths-guidelines-02         Nov 2011

   carefully, as they describe your rights and restrictions with respect
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Abstract

   Add-Paths is a BGP enhancement that allows a BGP router to advertise
   multiple distinct paths for the same prefix/NLRI. This provides a
   number of potential benefits, including reduced routing churn, faster
   convergence and better loadsharing.

   This document provides recommendations to implementers of Add-Paths
   so that network operators have the tools needed to address their
   specific applications and to manage the scalability impact of Add-
   Paths. A router implementing Add-Paths may learn many paths for a
   prefix and must decide which of these to advertise to peers. This
   document analyses different algorithms for making this selection and
   provides recommendations based on the target application.

Table of Contents

   1. Introduction...................................................4
   2. Terminology....................................................4
   3. Add-Paths Applications.........................................5
      3.1. Fast Connectivity Restoration.............................5
      3.2. Load Balancing............................................7
      3.3. Churn Reduction...........................................7
      3.4. Suppression of MED-Related Persistent Route Oscillation...7
   4. Implementation Guidelines......................................8
      4.1. Capability Negotiation....................................8
      4.2. Receiving Multiple Paths..................................9
      4.3. Advertising Multiple Paths................................9
         4.3.1. Path Selection Modes................................11
            4.3.1.1. Advertise All Paths............................11
            4.3.1.2. Advertise N Paths..............................12
            4.3.1.3. Advertise All AS-Wide Best Paths...............12
            4.3.1.4. Advertise ALL AS-Wide Best and Next-Best Paths
            (Double AS Wide)........................................13
         4.3.2. Derived Modes from Bounding the Number of Advertised
         Paths......................................................14
   5. Deployment Considerations.....................................14
      5.1. Introducing Add-Paths into an Existing Network...........14
      5.2. Scalability Considerations...............................16
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