Bidirectional Forwarding Detection (BFD) for Multi-point Networks and Virtual Router Redundancy Protocol (VRRP) Use Case
draft-mirsky-bfd-p2mp-vrrp-use-case-01

Versions: 00 01                                                         
BFD Working Group                                              G. Mirsky
Internet-Draft                                                 ZTE Corp.
Updates: 5798 (if approved)                                  J. Tantsura
Intended status: Standards Track                         October 3, 2017
Expires: April 6, 2018


 Bidirectional Forwarding Detection (BFD) for Multi-point Networks and
           Virtual Router Redundancy Protocol (VRRP) Use Case
                 draft-mirsky-bfd-p2mp-vrrp-use-case-01

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 and defines the
   extension to bootstrap point-to-multipoint BFD session.

Status of This Memo

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   This Internet-Draft will expire on April 6, 2018.

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   the Trust Legal Provisions and are provided without warranty as
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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 . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Applicability of p2mp BFD . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

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 extensions 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.  This document demonstrates how
   point-to-multipoint (p2mp) BFD can enable faster detection of Master
   failure and thus minimize service disruption in a VRRP domain.  The
   document also defines the extension to VRRP [RFC5798] to bootstrap a
   VRRP Backup router to join in p2mp BFD session.

1.1.  Conventions used in this document

1.1.1.  Terminology

   BFD: Bidirectional Forwarding Detection

   p2mp: Pont-to-Multipoint



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   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 BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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.  Figure 1 displays the extension
   of VRRP [RFC5798] to bootstrap tail of the p2mp BFD session.  Master
























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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Version| Type  | Virtual Rtr ID|   Priority    |Count IPvX Addr|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Rsvd |B|     Max Adver Int     |          Checksum             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                       IPvX Address(es)                        |
       +                                                               +
       +                                                               +
       +                                                               +
       +                                                               +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Master Discriminator                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 1: VRRP Extension to Bootstrap P2MP BFD session

   where new fields are interpreted as:

      B(FD) - one bit flag that indicates that the Master Discriminator
      field is appended to VRRP packet defined in [RFC5798];

      Master Discriminator - My Discriminator value allocated by the
      root of the p2mp BFD session.

   The Master router that is configured to use p2mp BFD to support
   faster convergence of VRRP starts transmitting BFD control packets
   with VRID as source IP address and My Discriminator.  The same value
   of My Discriminator MUST be set as value of Master Discriminator
   field and BFD flag MUST be set in the VRRP packet.  Backup router
   demultiplexes p2mp BFD test sessions based on VRID that it been
   configured with and the My Discriminator value it learns from the
   received VRRP packet.  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
   for p2mp BFD control packets.  If the latter is the case, then the
   Backup router MUST wait for VRRP packet from the new VRRP Master
   router that will bootstrap new p2mp BFD session.




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4.  IANA Considerations

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

5.  Security Considerations

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

6.  Acknowledgements

7.  Normative References

   [I-D.ietf-bfd-multipoint]
              Katz, D., Ward, D., and J. Networks, "BFD for Multipoint
              Networks", draft-ietf-bfd-multipoint-10 (work in
              progress), April 2017.

   [I-D.nitish-vrrp-bfd]
              Gupta, N., Dogra, A., Docherty, C., Mirsky, G., and J.
              Tantsura, "Fast failure detection in VRRP with BFD",
              draft-nitish-vrrp-bfd-04 (work in progress), August 2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5798]  Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP)
              Version 3 for IPv4 and IPv6", RFC 5798,
              DOI 10.17487/RFC5798, March 2010,
              <https://www.rfc-editor.org/info/rfc5798>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
              DOI 10.17487/RFC5881, June 2010,
              <https://www.rfc-editor.org/info/rfc5881>.

   [RFC5883]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
              June 2010, <https://www.rfc-editor.org/info/rfc5883>.





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   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Authors' Addresses

   Greg Mirsky
   ZTE Corp.

   Email: gregimirsky@gmail.com


   Jeff Tantsura

   Email: jefftant.ietf@gmail.com




































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