Bidirectional Forwarding Detection (BFD) Directed Return Path
draft-ietf-mpls-bfd-directed-07

Document Type Active Internet-Draft (mpls WG)
Last updated 2017-06-13
Replaces draft-mirsky-mpls-bfd-directed
Stream IETF
Intended RFC status Proposed Standard
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MPLS Working Group                                             G. Mirsky
Internet-Draft                                                       ZTE
Intended status: Standards Track                             J. Tantsura
Expires: December 15, 2017                                    Individual
                                                           I. Varlashkin
                                                                  Google
                                                                 M. Chen
                                                                  Huawei
                                                           June 13, 2017

     Bidirectional Forwarding Detection (BFD) Directed Return Path
                    draft-ietf-mpls-bfd-directed-07

Abstract

   Bidirectional Forwarding Detection (BFD) is expected to be able to
   monitor wide variety of encapsulations of paths between systems.
   When a BFD session monitors an explicitly routed unidirectional path
   there may be a need to direct egress BFD peer to use a specific path
   for the reverse direction of the BFD session.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on December 15, 2017.

Copyright Notice

   Copyright (c) 2017 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

Mirsky, et al.          Expires December 15, 2017               [Page 1]
Internet-Draft          BFD Directed Return Path               June 2017

   carefully, as they describe your rights and restrictions with respect
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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions used in this document . . . . . . . . . . . .   3
       1.1.1.  Requirements Language . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Control of the Reverse BFD Path . . . . . . . . . . . . . . .   3
     3.1.  BFD Reverse Path TLV  . . . . . . . . . . . . . . . . . .   3
     3.2.  Static and RSVP-TE sub-TLVs . . . . . . . . . . . . . . .   4
     3.3.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Use Case Scenario . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  BFD Reverse Path TLV  . . . . . . . . . . . . . . . . . .   5
     5.2.  Return Code . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   [RFC5880], [RFC5881], and [RFC5883] established the BFD protocol for
   IP networks.  [RFC5884] and [RFC7726] set rules of using BFD
   asynchronous mode over IP/MPLS LSPs.  These 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 a LSP is explicitly routed it is likely that the
   shortest return path to the ingress BFD peer would not follow the
   same path as the LSP in the forward direction.  The fact that BFD
   control packets are not guaranteed to follow the same links and nodes
   in both forward and reverse directions is a significant factor in
   producing false positive defect notifications, i.e. false alarms, if
   used by the ingress BFD peer to deduce the state of the forward
   direction.

   This document defines the BFD Reverse Path TLV as an extension to LSP
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