Bidirectional Forwarding Detection (BFD) Directed Return Path
draft-ietf-mpls-bfd-directed-05

Document Type Active Internet-Draft (mpls WG)
Last updated 2017-02-06
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: August 10, 2017                                      Individual
                                                           I. Varlashkin
                                                                  Google
                                                                 M. Chen
                                                                  Huawei
                                                        February 6, 2017

     Bidirectional Forwarding Detection (BFD) Directed Return Path
                    draft-ietf-mpls-bfd-directed-05

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 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 August 10, 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

Mirsky, et al.           Expires August 10, 2017                [Page 1]
Internet-Draft          BFD Directed Return Path           February 2017

   carefully, as they describe your rights and restrictions with respect
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   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.  Direct Reverse BFD Path . . . . . . . . . . . . . . . . . . .   3
     3.1.  Case of MPLS Data Plane . . . . . . . . . . . . . . . . .   3
       3.1.1.  BFD Reverse Path TLV  . . . . . . . . . . . . . . . .   3
       3.1.2.  Static and RSVP-TE sub-TLVs . . . . . . . . . . . . .   4
     3.2.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Use Case Scenario . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  TLV . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.2.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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
   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
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