Bidirectional Forwarding Detection (BFD) Directed Return Path
draft-mirsky-mpls-bfd-directed-00

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Last updated 2014-06-30
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MPLS Working Group                                             G. Mirsky
Internet-Draft                                               J. Tantsura
Intended status: Standards Track                                Ericsson
Expires: January 1, 2015                                   I. Varlashkin
                                                                 EasyNet
                                                           June 30, 2014

     Bidirectional Forwarding Detection (BFD) Directed Return Path
                   draft-mirsky-mpls-bfd-directed-00

Abstract

   Bidirectional Forwarding Detection (BFD) is expected to monitor bi-
   directional paths.  When forward direction of a BFD session is to
   monitor 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 January 1, 2015.

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   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Mirsky, et al.           Expires January 1, 2015                [Page 1]

Internet-Draft          BFD Directed Return Path               June 2014

   the Trust Legal Provisions and are provided without warranty as
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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 Satement  . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Direct Reverse BFD Path . . . . . . . . . . . . . . . . . . .   3
     3.1.  Case of MPLS Data Plane . . . . . . . . . . . . . . . . .   4
       3.1.1.  BFD Reverse Path TLV  . . . . . . . . . . . . . . . .   4
       3.1.2.  Segment Routing Tunnel sub-TLV  . . . . . . . . . . .   4
     3.2.  Case of IPv6 Data Plane . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  TLV . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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
   directions detection of Loss of Continuity (LoC) defect in forward
   direction is not guaranteed or free of positive negatives.

   This document proposes to use BFD Return Path TLV extension to LSP
   Ping [RFC4379] to instruct the far-end BFD peer to use explicit path
   for its BFD control packets associated with the particular BFD
   session.  As a special case, forward and reverse directions of the
   BFD session can form bi-directional co-routed associated channel.
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