Interoperability between the Virtual Router Redundancy Protocol and PIM
RFC 7910

Document Type RFC - Informational (June 2016; No errata)
Was draft-zhou-pim-vrrp (individual)
Last updated 2016-06-16
Stream ISE
Formats plain text pdf html bibtex
IETF conflict review conflict-review-zhou-pim-vrrp
Stream ISE state Published RFC
Consensus Boilerplate Unknown
Document shepherd Nevil Brownlee
Shepherd write-up Show (last changed 2016-03-15)
IESG IESG state RFC 7910 (Informational)
Telechat date
Responsible AD (None)
Send notices to "Nevil Brownlee" <rfc-ise@rfc-editor.org>
IANA IANA review state IANA OK - No Actions Needed
IANA action state No IC
Independent Submission                                           W. Zhou
Request for Comments: 7910                                 Cisco Systems
Category: Informational                                        June 2016
ISSN: 2070-1721

Interoperability between the Virtual Router Redundancy Protocol and PIM

Abstract

   This document introduces VRRP-aware PIM, a redundancy mechanism for
   the Protocol Independent Multicast (PIM) to interoperate with the
   Virtual Router Redundancy Protocol (VRRP).  It allows PIM to track
   VRRP state and to preserve multicast traffic upon failover in a
   redundant network with virtual routing groups enabled.  The mechanism
   described in this document is based on Cisco IOS software
   implementation.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7910.

Copyright Notice

   Copyright (c) 2016 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Zhou                          Informational                     [Page 1]
RFC 7910                VRRP PIM Interoperability              June 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Tracking and Failover . . . . . . . . . . . . . . . . . . . .   3
   3.  PIM Assert Metric Auto-Adjustment . . . . . . . . . . . . . .   4
   4.  DF Election for BiDir Group . . . . . . . . . . . . . . . . .   4
   5.  Tracking Multiple VRRP Groups on an Interface . . . . . . . .   5
   6.  Support of HSRP . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   6
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The Virtual Router Redundancy Protocol (VRRP) [RFC5798] is a
   redundancy protocol for establishing a fault-tolerant default router.
   The protocol establishes a framework between network devices in order
   to achieve default device failover if the primary devices become
   inaccessible.

   Protocol Independent Multicast (PIM) [RFC7761] has no inherent
   redundancy capabilities and its operation is completely independent
   of VRRP group states.  As a result, IP multicast traffic is not
   necessarily forwarded by the same device that is elected by VRRP.
   The VRRP-aware PIM feature provides consistent IP multicast
   forwarding in a redundant network with virtual routing groups
   enabled.

   In a multi-access segment (such as LAN), the elected PIM designated
   router (DR) is unaware of the redundancy configuration, and the
   elected DR and VRRP master router (MR) may not be the same.  In order
   to ensure that the PIM DR is always able to forward a PIM Join/Prune
   (J/P) message towards Rendezvous Point (RP) or first-hop router, the
   VRRP MR becomes the PIM DR (if there is only one VRRP group).  PIM is
   responsible for adjusting the DR priority based on the group state.
   When a failover occurs, multicast states are created on the new MR
   elected by the VRRP group and the MR assumes responsibility for the
   routing and forwarding of all the traffic addressed to the VRRP
   virtual IP address (vIP).  This ensures that the PIM DR runs on the
   same router as the VRRP MR and maintains multicast routing (mroute)
   states.  It enables multicast traffic to be forwarded through the
   VRRP MR, allowing PIM to leverage VRRP redundancy, avoid potential
   duplicate traffic, and enable failover, depending on the VRRP states
   in the router.

Zhou                          Informational                     [Page 2]
RFC 7910                VRRP PIM Interoperability              June 2016

   This mechanism can be safely deployed into a PIM network without
Show full document text