BGP BFD Strict-Mode
draft-merciaz-idr-bgp-bfd-strict-mode-01

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IDR WorkGroup                                                   M. Zheng
Internet-Draft                                                 A. Lindem
Intended status: Standards Track                           Cisco Systems
Expires: October 5, 2019                                   April 3, 2019

                          BGP BFD Strict-Mode
                draft-merciaz-idr-bgp-bfd-strict-mode-01

Abstract

   This document specifies extensions to RFC4271 BGP-4 that enable a BGP
   speaker to signal additional Bidirectional Forwarding Detection (BFD)
   extensions using an optional parameter BFD capability.  This BFD
   capability enables a BGP speaker to prevent a BGP session from being
   established until a BFD session is established.  It is referred to as
   BGP BFD "strict-mode".  BGP BFD strict-mode will be supported when
   both the local speaker and its remote peer are BFD strict-mode
   capable, Otherwise, a BGP speaker and its peer should not require a
   BFD session for BGP session establishment.

Status of This Memo

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Zheng & Lindem           Expires October 5, 2019                [Page 1]
Internet-Draft             BGP BFD Strict-Mode                April 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  BFD Capability  . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Bidirectional Forwarding Detection BFD [RFC5882] enables routers to
   monitor data plane connectivity and to detect faults in the
   bidirectional forwarding path between them.  This capability is
   leveraged by routing protocols such as BGP [RFC4271] to rapidly react
   to topology changes in the face of path failures.

   The BFD interaction with BGP is specified in Section 10.2 of
   [RFC5882].  When BFD is enabled for a BGP neighbor, faults in the
   bidirectional forwarding detected by BFD result in session
   termination.  It is possible in some failure scenarios for the
   network to be in a state such that a BGP session may be established
   but a BFD session cannot be established.  In some other scenarios, it
   may be possible to establish a BGP session, but a degraded or poor-
   quality link may result in the corresponding BFD session going up and
   down frequently.

   To avoid situations which result in routing churn and to minimize the
   impact of network interruptions, it will be beneficial to disallow
   BGP to establish a neighbor session until s BFD session is
   successfully established and has stabilized.  We refer to this mode
   of operation as BGP BFD "strict-mode".  However, always using
   "strict-mode" would preclude BGP operation in an environment where
   not all routers support BFD strict-mode or have BFD enabled.  This
   document defines BGP "strict-mode" operation as preventing BGP
   session establishment until both the local and remove speakers have a
   stable BFD session.  The document also specifies the BGP protocol
   extensions for BGP capability [RFC5492] for announcing BFD parameters
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