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

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Last updated 2020-06-30
Replaces draft-ketant-lsr-ospf-bfd-strict-mode
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Link State Routing                                         K. Talaulikar
Internet-Draft                                                 P. Psenak
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: January 1, 2021                                           A. Fu
                                                               Bloomberg
                                                               M. Rajesh
                                                        Juniper Networks
                                                           June 30, 2020

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

Abstract

   This document specifies the extensions to OSPF that enable an OSPF
   router to signal the requirement for a Bidirectional Forwarding
   Detection (BFD) session prior to adjacency formation.  Link-Local
   Signaling (LLS) is used to advertise this requirement of "strict-
   mode" of BFD session establishment for OSPF adjacency.  If both OSPF
   neighbors advertise the "strict-mode" of BFD, adjacency formation
   will be blocked until a BFD session has been successfully
   established.

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 January 1, 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

Talaulikar, et al.       Expires January 1, 2021                [Page 1]
Internet-Draft          OSPF Strict-Mode for BFD               June 2020

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  LLS B-bit Flag  . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Local Interface IPv4 Address TLV  . . . . . . . . . . . . . .   3
   4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  OSPFv3 IPv4 Address-Family Specifics  . . . . . . . . . .   6
     4.2.  Graceful Restart Considerations . . . . . . . . . . . . .   6
   5.  Operations & Management Considerations  . . . . . . . . . . .   6
   6.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Bidirectional Forwarding Detection (BFD) [RFC5880] enables routers to
   monitor dataplane connectivity and to detect faults in the
   bidirectional path between them.  BFD is leveraged by routing
   protocols like OSPFv2[RFC2328] and OSPFv3 [RFC5340] to detect
   connectivity failures for established adjacencies and trigger the
   rerouting of traffic around the failure more quickly than with OSPF
   hello packet monitoring.

   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 packets.
   Faults in the bidirectional forwarding detected via BFD then result
   in the OSPF adjacency being brought down.  Note that it is possible
   in some failure scenarios for the network to be in a state such that
   an OSPF adjacency can be established but a BFD session cannot be
   established and maintained.  In certain other scenarios, a degraded
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