Bidirectional Forwarding Detection (BFD) Directed Return Path
draft-mirsky-mpls-bfd-directed-02

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MPLS Working Group                                             G. Mirsky
Internet-Draft                                               J. Tantsura
Intended status: Standards Track                                Ericsson
Expires: August 16, 2015                                   I. Varlashkin
                                                                  Google
                                                                 M. Chen
                                                                  Huawei
                                                       February 12, 2015

     Bidirectional Forwarding Detection (BFD) Directed Return Path
                   draft-mirsky-mpls-bfd-directed-02

Abstract

   Bidirectional Forwarding Detection (BFD) is expected to monitor bi-
   directional paths.  When a BFD session monitors in its forward
   direction an explicitly routed path there is a need to be able to
   direct far-end BFD peer to use specific path as reverse direction of
   the BFD session.

Status of This Memo

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   This Internet-Draft will expire on August 16, 2015.

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Mirsky, et al.           Expires August 16, 2015                [Page 1]

Internet-Draft          BFD Directed Return Path           February 2015

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions used in this document . . . . . . . . . . . .   3
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Direct Reverse BFD Path . . . . . . . . . . . . . . . . . . .   4
     3.1.  Case of MPLS Data Plane . . . . . . . . . . . . . . . . .   4
       3.1.1.  BFD Reverse Path TLV  . . . . . . . . . . . . . . . .   4
       3.1.2.  Segment Routing Tunnel sub-TLV  . . . . . . . . . . .   5
     3.2.  Case of IPv6 Data Plane . . . . . . . . . . . . . . . . .   5
     3.3.  Bootstrapping BFD session with BFD Reverse Path over
           Segment Routed tunnel . . . . . . . . . . . . . . . . . .   6
     3.4.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Use Case Scenario . . . . . . . . . . . . . . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  TLV . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.3.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The [RFC5880], [RFC5881], and the [RFC5883] established BFD protocol
   for IP networks and the [RFC5884] set rules of using BFD Asynchronous
   mode over IP/MPLS LSPs.  All standards implicitly assume that the
   far-end BFD peer will use the best route regardless of route being
   used to send BFD control packets towards it.  As result, if the near-
   end BFD peer sends its BFD control packets over explicit path that is
   diverging from the best route, then reverse direction of the BFD
   session is likely not to be on co-routed bi-directional path with the
   forward direction of the BFD session.  And because BFD control
   packets are not guaranteed to cross the same links and nodes in both
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