BFD in Demand Mode over Point-to-Point MPLS LSP
draft-mirsky-bfd-mpls-demand-03

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Last updated 2018-10-17 (latest revision 2018-06-19)
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BFD Working Group                                              G. Mirsky
Internet-Draft                                                 ZTE Corp.
Intended status: Standards Track                           June 19, 2018
Expires: December 21, 2018

            BFD in Demand Mode over Point-to-Point MPLS LSP
                    draft-mirsky-bfd-mpls-demand-03

Abstract

   This document describes procedures for using Bidirectional Forwarding
   Detection (BFD) in Demand mode to detect data plane failures in
   Multiprotocol Label Switching (MPLS) point-to-point Label Switched
   Paths.

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 21, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   2
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   3.  Use of the BFD Demand Mode  . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   [RFC5884] defined use of the Asynchronous method of Bidirectional
   Detection (BFD) [RFC5880] to monitor and detect failures in the data
   path of a Multiprotocol Label Switching (MPLS) Label Switched Path
   (LSP).  Use of the Demand mode, also specified in [RFC5880], has not
   been defined so far.  This document describes procedures for using
   the Demand mode of BFD protocol to detect data plane failures in MPLS
   point-to-point (p2p) LSPs.

2.  Conventions used in this document

2.1.  Terminology

   MPLS: Multiprotocol Label Switching

   LSP: Label Switched Path

   LER: Label switching Edge Router

   BFD: Bidirectional Forwarding Detection

   p2p: Point-to-Point

2.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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3.  Use of the BFD Demand Mode

   [RFC5880] defines that the Demand mode MAY be:

   o  asymmetric, i.e. used in one direction of a BFD session;

   o  switched to and from without bringing BFD session to Down state
      through using a Poll Sequence.

   For the case of BFD over MPLS LSP, ingress Label switching Edge
   Router (LER) usually acts as Active BFD peer and egress LER acts as
   Passive BFD peer.  The Active peer bootstraps the BFD session by
   using LSP ping.  Once the BFD session is in Up state the ingress LER
   that supports this specification MUST switch to the Demand mode by
   setting Demand (D) bit in its Control packet and initiating a Poll
   Sequence.  If the egress LER supports this specification it MUST
   respond with the Final (F) bit set in its BFD Control packet sent to
   the ingress LER and ceases further transmission of periodic BFD
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