Unaffiliated BFD Echo Function
draft-ietf-bfd-unaffiliated-echo-00

Document Type Active Internet-Draft (bfd WG)
Last updated 2020-09-10
Replaces draft-cw-bfd-unaffiliated-echo
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BFD Working Group                                               W. Cheng
Internet-Draft                                                   R. Wang
Updates: 5880 (if approved)                                 China Mobile
Intended status: Standards Track                                  X. Min
Expires: March 13, 2021                                           A. Liu
                                                               ZTE Corp.
                                                               R. Rahman
                                                           Cisco Systems
                                                           R. Boddireddy
                                                        Juniper Networks
                                                       September 9, 2020

                     Unaffiliated BFD Echo Function
                  draft-ietf-bfd-unaffiliated-echo-00

Abstract

   Bidirectional Forwarding Detection (BFD) is a fault detection
   protocol that can quickly determine a communication failure between
   two forwarding engines.  This document proposes a use of BFD echo
   where the local system supports BFD but the neighboring system does
   not support BFD.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   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 March 13, 2021.

Copyright Notice

   Copyright (c) 2020 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

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

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Unaffiliated BFD Echo Behavior  . . . . . . . . . . . . . . .   3
   3.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   To minimize the impact of device faults on services and improve
   network availability, a network device must be able to quickly detect
   faults in communication with adjacent devices.  Measures can then be
   taken to promptly rectify the faults to ensure service continuity.

   BFD [RFC5880] is a low-overhead, short-duration method to detect
   faults on the path between adjacent forwarding engines.  The faults
   can be interface, data link, and even forwarding engine faults.  It
   is a single, unified mechanism to monitor any media and protocol
   layers in real time.

   BFD defines asynchronous mode to satisfy various deployment
   scenarios, also supports echo function to reduce the device
   requirement for BFD.  When the echo function is activated, the local
   system sends a BFD echo packet and the remote system loops back the
   packet through the forwarding path.  If several consecutive echo
   packets are not received, the session is declared to be Down.

   When using BFD echo function, it is not clear whether the devices
   using echo function need to support the full BFD procotol, including
   maintaining the state machine of BFD session as described in
   [RFC5880] and [RFC5881].  According to different understanding, there
   are two typical scenarios as below:

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