Bidirectional Forwarding Detection (BFD) Directed Return Path
draft-ietf-mpls-bfd-directed-10

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MPLS Working Group                                             G. Mirsky
Internet-Draft                                                       ZTE
Intended status: Standards Track                             J. Tantsura
Expires: April 1, 2019                                    Nuage Networks
                                                           I. Varlashkin
                                                                  Google
                                                                 M. Chen
                                                                  Huawei
                                                      September 28, 2018

     Bidirectional Forwarding Detection (BFD) Directed Return Path
                    draft-ietf-mpls-bfd-directed-10

Abstract

   Bidirectional Forwarding Detection (BFD) is expected to be able to
   monitor a 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.

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on April 1, 2019.

Copyright Notice

   Copyright (c) 2018 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

Mirsky, et al.            Expires April 1, 2019                 [Page 1]
Internet-Draft          BFD Directed Return Path          September 2018

   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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 . . . . . . . . . . . . . . .   5
     3.3.  Return Codes  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Use Case Scenario . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  BFD Reverse Path TLV  . . . . . . . . . . . . . . . . . .   6
     5.2.  Return Code . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   [RFC5880], [RFC5881], and [RFC5883] established the BFD protocol for
   IP networks.  [RFC5884] and [RFC7726] set rules for using BFD
   asynchronous mode over IP/MPLS LSPs.  These standards do not define
   means to control the path selection at the egress BFD peer to send
   BFD control packets towards the ingress BFD system.

   For the case when BFD is used to detect defects of the traffic
   engineered LSP the path the BFD control packets transmitted by the
   egress BFD system toward the ingress may be disjoint from 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 may be one of the factors contributing to
   producing false positive defect notifications, i.e., false alarms, at
   the ingress BFD peer.  Ensuring that both directions of the BFD
   session use co-routed paths may, in some environments, improve the
   determinism of the failure detection and localization.

   This document defines the BFD Reverse Path TLV as an extension to LSP
   Ping [RFC8029] and proposes that it is to be used to instruct the