OSPF BFD Strict-Mode
draft-ketant-lsr-ospf-bfd-strict-mode-01

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Last updated 2019-03-11
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Link State Routing                                         K. Talaulikar
Internet-Draft                                                 P. Psenak
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: September 12, 2019                               March 11, 2019

                          OSPF BFD Strict-Mode
                draft-ketant-lsr-ospf-bfd-strict-mode-01

Abstract

   This document specifies the extensions to OSPF that enables a router
   and its neighbor to signal their intention to use Bidirectional
   Forwarding Detection (BFD) for their adjacency using link-local
   advertisement between them.  The signaling of this BFD enablement,
   allows the router to block and not allow the establishment of
   adjacency with its neighbor router until a BFD session is
   successfully established between them.  The document describes this
   "strict-mode" of BFD establishment as a prerequisite to OSPF
   adjacency formation.

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.

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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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 12, 2019.

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Copyright Notice

   Copyright (c) 2019 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
   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
   2.  LLS B-bit Flag  . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Operations & Management Considerations  . . . . . . . . . . .   5
   5.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Bidirectional Forwarding Detection (BFD) [RFC5880] enables routers to
   monitor dataplane connectivity over links between them and to detect
   faults in the bidirectional path between them.  This capability is
   leveraged by routing protocols like Open Shortest Path First (OSPFv2)
   [RFC2328] and OSPFv3 [RFC5340] to detect connectivity failures for
   their adjacencies and trigger the rerouting of traffic around this
   failure more quickly than their periodic hello messaging based
   detection mechanism.

   The use of BFD for monitoring routing protocols adjacencies is
   described in [RFC5882].  When BFD monitoring is enabled for OSPF
   adjacencies, the BFD session is bootstrapped based on the neighbor
   address information discovered by the exchange of OSPF hello
   messages.  Faults in the bidirectional forwarding detected via BFD
   then result in the bringing down of the OSPF adjacency.  Note that it
   is possible in some failure scenarios for the network to be in a

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   state such that the OSPF adjacency is capable of coming up, but the
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