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Bidirectional Forwarding Detection (BFD) for Multi-point Networks and Virtual Router Redundancy Protocol (VRRP) Use Case
draft-mirsky-bfd-p2mp-vrrp-use-case-05

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This is an older version of an Internet-Draft whose latest revision state is "Replaced".
Authors Greg Mirsky , Jeff Tantsura , Gyan Mishra
Last updated 2020-11-01 (Latest revision 2020-07-27)
Replaced by draft-mtm-rtgwg-vrrp-p2mp-bfd
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draft-mirsky-bfd-p2mp-vrrp-use-case-05
BFD Working Group                                              G. Mirsky
Internet-Draft                                                 ZTE Corp.
Updates: 5798 (if approved)                                  J. Tantsura
Intended status: Standards Track                                  Apstra
Expires: May 5, 2021                                           G. Mishra
                                                            Verizon Inc.
                                                        November 1, 2020

 Bidirectional Forwarding Detection (BFD) for Multi-point Networks and
           Virtual Router Redundancy Protocol (VRRP) Use Case
                 draft-mirsky-bfd-p2mp-vrrp-use-case-05

Abstract

   This document discusses the use of Bidirectional Forwarding Detection
   (BFD) for multipoint networks to provide Virtual Router Redundancy
   Protocol (VRRP) with sub-second Master convergence and defines the
   extension to bootstrap point-to-multipoint BFD session.

   This draft updates RFC 5798.

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
   and may be updated, replaced, or obsoleted by other documents at any
   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 May 5, 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

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   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
     1.1.  Conventions used in this document . . . . . . . . . . . .   3
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Applicability of p2mp BFD . . . . . . . . . . . . . . . . . .   3
     3.1.  Multipoint BFD Encapsulation  . . . . . . . . . . . . . .   5
   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 a faster switchover to a Backup router.  Using such capability
   with the software-based implementation of VRRP 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 a failure of the Master router
   within 100 msec or faster.

   [RFC8562] 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.

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1.1.  Conventions used in this document

1.1.1.  Terminology

   BFD: Bidirectional Forwarding Detection

   p2mp: Pont-to-Multipoint

   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 challenging.  BFD already has many
   implementations based on HW that are capable of supporting multiple
   sub-second sessions concurrently.

3.  Applicability of p2mp BFD

   [RFC8562] may provide an efficient and scalable solution for fast-
   converging environment that uses the default route rather than
   dynamic routing.  Each redundancy group presents itself as a 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) - a 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 a source IP address and My Discriminator.  The same
   value of My Discriminator MUST be set as the value of the Master
   Discriminator field.  The 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 the failure
   of the Master router it re-evaluates its role in the VRID.  As a
   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 the
   source IP address for p2mp BFD control packets.  If the latter is the
   case, then the Backup router MUST wait for the VRRP packet from the
   new VRRP Master router that will bootstrap the new p2mp BFD session.

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3.1.  Multipoint BFD Encapsulation

   The MultipointHead of p2mp BFD session when transmitting BFD control
   packet:

      MUST set TTL value to 1 (though note that VRRP packets have TTL
      set to 255);

      SHOULD use group address VRRP ('224.0.0.18' for IPv4 and
      'FF02:0:0:0:0:0:0:12' for IPv6) as destination IP address

      MAY use network broadcast address for IPv4 or link-local all nodes
      multicast group for IPv6 as destination IP address;

      MUST set destination UDP port value to 3784 when transmitting BFD
      control packets, as defined in [RFC8562];

      MUST use the Master IP address as the source IP address.

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
   [RFC8562], apply to this document.

6.  Acknowledgements

7.  Normative References

   [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>.

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   [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>.

   [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>.

   [RFC8562]  Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky,
              Ed., "Bidirectional Forwarding Detection (BFD) for
              Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562,
              April 2019, <https://www.rfc-editor.org/info/rfc8562>.

Authors' Addresses

   Greg Mirsky
   ZTE Corp.

   Email: gregimirsky@gmail.com

   Jeff Tantsura
   Apstra

   Email: jefftant.ietf@gmail.com

   Gyan Mishra
   Verizon Inc.

   Email: gyan.s.mishra@verizon.com

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