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BFD Working Group                                              G. Mirsky
Internet-Draft                                               J. Tantsura
Intended status: Informational                                  Ericsson
Expires: January 7, 2016                                    July 6, 2015


 Bidirectional Forwarding Detection (BFD) for Multi-point Networks and
           Virtual Router Redundancy Protocol (VRRP) Use Case
                 draft-mirsky-bfd-p2mp-vrrp-use-case-00

Abstract

   This document discusses use of Bidirectional Forwarding Detection
   (BFD) for multi-point networks to provide Virtual Router Redundancy
   Protocol (VRRP) with sub-second Master convergence.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on January 7, 2016.

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   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions used in this document . . . . . . . . . . . .   2
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   2
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   2
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Applicability of p2mp BFD . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   The [RFC5798] is the current specification of the Virtual Router
   Redundancy Protocol (VRRP) for IPv4 and IPv6 networks.  VRRPv3 allows
   for faster switchover to a Backup router.  Using such capability with
   software-based implementation of VRRP is may prove challenging.  But
   it still may be possible to deploy VRRP and provide sub-second
   detection of Master router failure by Backup routers.

   Bidirectional Forwarding Detection (BFD) [RFC5880] had been
   originally defined detect failure of point-to-point (p2p) paths:
   single-hop [RFC5881], multihop [RFC5883].  Single-hop BFD may be used
   to enable Backup routers to detect failure of the Master router
   within 100 msec or faster.  [I-D.nitish-vrrp-bfd] demonstrates how,
   with some extenstions to [RFC5798], that can be achieved.

   [I-D.ietf-bfd-multipoint] extends [RFC5880] for multipoint and
   multicast networks, which is precisely characterizes deployment
   scenarios for VRRP over LAN segment.

1.1.  Conventions used in this document

1.1.1.  Terminology

   BFD: Bidirectional Forwarding Detection

   VRRP: Virtual Router Redundancy Protocol

1.1.2.  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
   [RFC2119].



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2.  Problem Statement

   A router may be part of several Virtual Router Redundancy groups, as
   Master in some and as Backup in others.  Supporting sub-second mode
   for VRRPv3 [RFC5798] for all these roles without specialized support
   in data plane may prove to be very challenging.  BFD already has many
   implementations based on HW that are capable to support multiple sub-
   second session concurrently.

3.  Applicability of p2mp BFD

   [I-D.ietf-bfd-multipoint] may provide the efficient and scaleable
   solution for fast-converging environment that uses default route
   rather than dynamic routing.  Each redundancy group presents itself
   as p2mp BFD session with its Master being the root and Backup routers
   being tails of the p2mp BFD session.  The Master router starts
   transmitting BFD control packets with VRID as source IP address.
   Backup router demultiplexes p2mp BFD test sessions based on VRID that
   it been configured with.  Once Backup router accepts p2mp session
   from the new Master router backup router the Backup router MAY use My
   Discriminator from received p2mp BFD control packet to demultiplex
   p2mp BFD sessions.  When a Backup router detects failure of the
   Master router it re-evaluates its role in the VRID.  As result, the
   Backup router may become the Master router of the given VRID or
   continue as a Backup router.  If the former is the case, then the new
   Master router MUST select My Discriminator and start transmitting
   p2mp BFD control packets using Master IP address as source IP address
   fro p2mp BFD control packets.  If the latter is the case, then the
   Backup router MUST wait for p2mp BFD control packet with source IP
   address set to VRID.

4.  IANA Considerations

   This document makes no requests for IANA allocations.  This section
   may be deleted by RFC Editor.

5.  Security Considerations

   Secuirity considerations discussed in [RFC5798], [RFC5880], and
   [I-D.ietf-bfd-multipoint], apply to this document.

6.  Acknowledgements

7.  Normative References







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   [I-D.ietf-bfd-multipoint]
              Katz, D., Ward, D., and J. Networks, "BFD for Multipoint
              Networks", draft-ietf-bfd-multipoint-06 (work in
              progress), May 2015.

   [I-D.nitish-vrrp-bfd]
              Gupta, N., Dogra, A., and C. Docherty, "Fast failure
              detection using peer learning in VRRP with BFD", draft-
              nitish-vrrp-bfd-01 (work in progress), June 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5798]  Nadas, S., "Virtual Router Redundancy Protocol (VRRP)
              Version 3 for IPv4 and IPv6", RFC 5798, March 2010.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, June 2010.

   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, June
              2010.

   [RFC5883]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for Multihop Paths", RFC 5883, June 2010.

Authors' Addresses

   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com


   Jeff  Tantsura
   Ericsson

   Email: jeff.tantsura@ericsson.com













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