Bidirectional Forwarding Detection (BFD) Directed Return Path
draft-ietf-mpls-bfd-directed-03

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Document Type Active Internet-Draft (mpls WG)
Last updated 2016-08-17
Replaces draft-mirsky-mpls-bfd-directed
Stream IETF
Intended RFC status Proposed Standard
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MPLS Working Group                                             G. Mirsky
Internet-Draft                                                  Ericsson
Intended status: Standards Track                             J. Tantsura
Expires: February 18, 2017
                                                           I. Varlashkin
                                                                  Google
                                                                 M. Chen
                                                                  Huawei
                                                         August 17, 2016

     Bidirectional Forwarding Detection (BFD) Directed Return Path
                    draft-ietf-mpls-bfd-directed-03

Abstract

   Bidirectional Forwarding Detection (BFD) is expected to monitor any
   kind of paths between systems.  When a BFD session monitors an
   explicitly routed uni-directional path there may be a need to direct
   egress BFD peer to use specific path for the reverse direction of the
   BFD session.

Status of This Memo

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   This Internet-Draft will expire on February 18, 2017.

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   Copyright (c) 2016 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
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   publication of this document.  Please review these documents

Mirsky, et al.          Expires February 18, 2017               [Page 1]
Internet-Draft          BFD Directed Return Path             August 2016

   carefully, as they describe your rights and restrictions with respect
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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.  Static and RSVP-TE sub-TLVs . . . . . . . . . . . . .   5
       3.1.3.  Segment Routing: MPLS Data Plane Case . . . . . . . .   5
     3.2.  Bootstrapping BFD session with BFD Reverse Path over
           Segment Routed tunnel . . . . . . . . . . . . . . . . . .   6
     3.3.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Use Case Scenario . . . . . . . . . . . . . . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  TLV . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.3.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   RFC 5880 [RFC5880], RFC 5881 [RFC5881], and RFC 5883 [RFC5883]
   established the BFD protocol for IP networks and RFC 5884 [RFC5884]
   set rules of using BFD asynchronous mode over IP/MPLS LSPs.  These
   four standards implicitly assume that the egress BFD peer will use
   the shortest path route regardless of route being used to send BFD
   control packets towards it.

   For the case where an LSP is explicitly routed, if it is desired that
   BFD control packets follow the same path in the reverse direction
   (for support of common fault detection for explicitly routed
   bidirectional co-routed LSPs, for example), it is likely that the
   shortest return path to the ingress BFD peer may not follow the same
   path as the LSP in the forward direction.  The fact that BFD control
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