Skip to main content

Multicast Redundant Ingress Router Failover
draft-ietf-mboned-redundant-ingress-failover-09

Document Type Active Internet-Draft (mboned WG)
Authors Greg Shepherd , Zheng Zhang , Yisong Liu , Ying Cheng , Gyan Mishra
Last updated 2026-03-11 (Latest revision 2025-11-02)
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Formats
Reviews
Additional resources Mailing list discussion
Stream WG state In WG Last Call
Associated WG milestone
Jul 2025
Submit Multicast Redundant Ingress Router Failover to the IESG
Document shepherd (None)
IESG IESG state I-D Exists
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-ietf-mboned-redundant-ingress-failover-09
MBONED WG                                                    G. Shepherd
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Informational                             Z. Zhang, Ed.
Expires: 6 May 2026                                      ZTE Corporation
                                                                  Y. Liu
                                                            China Mobile
                                                                Y. Cheng
                                                            China Unicom
                                                               G. Mishra
                                                            Verizon Inc.
                                                         2 November 2025

              Multicast Redundant Ingress Router Failover
            draft-ietf-mboned-redundant-ingress-failover-09

Abstract

   This document is intended to serve as a guide for multicast network
   operators of various replication technologies to evaluate the options
   and tradeoffs in deploying redundant ingress router failover.
   Section 5 of RFC9026 details the hot root standby solution for MVPN
   networks.  Here we attempt to extend the discussion to cover
   additional multicast deployment solutions beyond MVPNs.  This
   document compares cold, warm, and hot standby modes, listing their
   advantages, limitations and deployment considerations to help
   identify the appropriate solution for any network.

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 6 May 2026.

Shepherd, et al.           Expires 6 May 2026                   [Page 1]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

Copyright Notice

   Copyright (c) 2025 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 carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Ingress Router Failover . . . . . . . . . . . . . . . . . . .   4
   4.  Stand-by Modes  . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Cold Standby Mode . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Warm Standby Mode . . . . . . . . . . . . . . . . . . . .   8
     4.3.  Hot Standby Mode  . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Summary . . . . . . . . . . . . . . . . . . . . . . . . .   9
   5.  Failure detection . . . . . . . . . . . . . . . . . . . . . .  11
   6.  Deployment Considerations . . . . . . . . . . . . . . . . . .  12
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   Multicast redundant ingress router failover is an important issue in
   multicast deployments, especially in backbone multicast domains or
   multicast provider domains.  Backbone multicast domains or multicast
   provider domains are referred to as multicast domains in the
   following sections.  A multicast domain is a domain used to forward
   multicast flow based on specific multicast technologies, such as PIM
   [RFC7761], BIER [RFC8279], P2MP TE tunnel [RFC4875], MLDP [RFC6388],
   etc.  Static configuration, tunnel based technologies, such as AMT
   [RFC7450], SR P2MP policies [I-D.ietf-pim-sr-p2mp-policy] can also be
   used.  The domain may or may not be directly connected to the actual
   multicast source and receivers.

Shepherd, et al.           Expires 6 May 2026                   [Page 2]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

   The ingress device of the multicast domain, such as the ingress
   router, can be connected to the multicast source by a single hop or
   multiple hops.  In PIM, it is also called the first hop router, in
   BIER, it is called the BFIR, and in P2MP TE tunnel or MLDP, it is
   called the ingress LSR.

   The egress device of the multicast domain, such as the egress router,
   may be connected to the multicast receiver by a single hop or
   multiple hops.  In PIM, it is also called the last hop router, in
   BIER, it is called the BFER, and in P2MP TE tunnel or MLDP, it is
   called the egress LSR.

   In order to ensure the reliability of multicast flow, there may be
   two or more ingress devices or egress devices in the multicast
   domain.  That means the same multicast flow may enter the multicast
   domain from multiple ingress devices of the multicast domain.  This
   draft does not discuss the protection method between the ingress
   device and the multicast source, between the egress device and the
   receiver, nor does it discuss the details of the technologies such as
   PIM and BIER.  It only discusses the failover issues of the multicast
   domain ingress router.

   This document is intended to serve as a guide for multicast network
   operators of various replication technologies to evaluate the options
   and tradeoffs in deploying redundant ingress router failover.
   Section 5 of RFC9026 details the hot root standby solution for MVPN
   networks.  Here we attempt to extend the discussion to cover
   additional multicast deployment solutions beyond MVPNs.  This
   document compares cold, warm, and hot standby modes, listing their
   advantages, limitations and deployment considerations to help
   identify the appropriate solution for any network.

2.  Terminology

   The following abbreviations are used in this document:

   IR: An ingress router for multicast flows in a multicast domain.

   ER: An egress router for multicast flows in a multicast domain.

   SIR: The IR whose traffic is received by the egress router is called
   Selected-IR, or SIR for short.

   BIR: The IR may or may not send multicast flows.  Multicast streams
   sent by this IR will not be received by the ER.  If the SIR fails,
   the IR will take over the SIR's role.  This type of IR is called a
   backup IR, or BIR for short.

Shepherd, et al.           Expires 6 May 2026                   [Page 3]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

3.  Ingress Router Failover

                                 source
                                  ...
                            +-----+      +-----+
                 +----------+ IR1 +------+ IR2 +---------+
                 |multicast +-----+      +-----+         |
                 |domain            ...                  |
                 |                                       |
                 |          +-----+      +-----+         |
                 |          | Rm  |      | Rn  |         |
                 |          ++---++      +--+--+         |
                 |           |   |          |            |
                 |     +-----+   +---+      +-----+      |
                 |     |             |            |      |
                 |   +-v---+      +--v--+      +--v--+   |
                 +---+ ER1 +------+ ER2 +------+ ER3 +---+
                     +-----+      +-----+      +-----+
                      ...           ...          ...
                    receiver      receiver     receiver
                                 Figure 1

   This is a common multicast networking scenario.  The multicast domain
   includes the area from IR to ER.  The flow sent by the multicast
   source enters the multicast domain from at least one IR, is forwarded
   in the multicast domain, reaches the ER, is forwarded by the ER, and
   finally the receiver receives the multicast flow.

   The ingress device IR of the multicast domain is a key node for the
   normal forwarding of multicast flows.  When two or more IRs are
   deployed, there may be multiple protection modes for IR, such as cold
   standby, warm standby and hot standby.  These modes are also
   described in [RFC9026].  However, [RFC9026] mainly focuses on
   signaling notifications in MVPN scenarios and does not involve the
   protection mode of multiple ingress devices in the multicast domain
   and the impact on multicast flow transmission in the multicast
   domain.

   As shown in Figure 1, a same multicast flow enters the multicast
   domain from two IRs.  Both IRs are UMH (Upflow Multicast Hop)
   candidates of ER.  Different multicast technologies may be used in
   the multicast domain according to the deployment of the network
   administrator.  Assuming that PIM technology is used, two multicast
   trees can be pre-established with two IRs as roots.

Shepherd, et al.           Expires 6 May 2026                   [Page 4]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

   When a node or link in the multicast domain fails, the forwarding of
   multicast flow may be affected.  However, it is not necessary to
   switch multicast flow from SIR to BIR in all cases.  The following
   are situations where switching is not required:

   *  When PIM is used as the multicast forwarding protocol in a domain,
      a forwarding tree of (S, G) or (*, G) is pre-built.  When a node
      other than SIR or a link in the forwarding tree fails, the tree is
      partially rebuilt.

   *  When BIER is used as the multicast forwarding protocol in a
      multicast domain, when a node other than SIR or a link in the
      domain fails, there is no need to rebuild the forwarding path,
      BIER forwarding will be restored as the IGP route converges.

   *  When P2MP TE tunnel or MLDP is used as the multicast forwarding
      protocol in a multicast domain, a forwarding LSP is pre-
      established.  When a node other than the SIR in the LSP or a link
      in the domain fails, the LSP may be partially rebuilt.

   *  When a static multicast tree or SR P2MP policy is used in a
      multicast domain, when a node other than the SIR on the forwarding
      path or a link has a problem, the controller needs to recalculate
      a new forwarding path to bypass the faulty node or link.

   When a critical failure occurs, it is necessary to switch from SIR to
   BIR, for example: SIR encounters a device failure, or the forwarding
   channel between SIR and ER fails, causing ER to be unable to receive
   multicast flows from SIR, and this failure cannot be restored in a
   short time.  At this time, the multicast flow will be forwarded by
   BIR.  ER receives the flow forwarded by BIR and forwards it to the
   receiver.

Shepherd, et al.           Expires 6 May 2026                   [Page 5]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

                                   source
                                    ...
                            +-----+      +-----+
                 +----------+ IR1 +------+ IR2 +---------+
                 |          +--+--+      +--+--+         |
                 |             |            |            |
                 |          +--+--+      +--+--+         |
                 |          | Rx  |      | Ry  |         |
                 |          +-+-+-+      ++---++         |
                 |            | |         |   |          |
                 |            | +-----------+ |          |
                 |            |           | | |          |
                 |            | +---------+ | |          |
                 |            | |           | |          |
                 |          +-v-v-+      +--v-v+         |
                 |          | Rm  |      | Rn  |         |
                 |          ++---++      +--+--+         |
                 |           |   |          |            |
                 |     +-----+   +---+      +-----+      |
                 |     |             |            |      |
                 |   +-v---+      +--v--+      +--v--+   |
                 +---+ ER1 +------+ ER2 +------+ ER3 +---+
                     +-----+      +-----+      +-----+
                      ...           ...          ...
                    receiver      receiver     receiver
                                 Figure 2

   For example, in Figure 2, there is only one path in some areas of the
   network.  IR1 and Rx are key nodes in the domain.  When IR1 or Rx
   fails, there is no other path between IR1 and ER.

   *  When PIM is used in the multicast domain, Rm and Rn can select Ry
      as the upflow node, send Join messages, and build a new tree with
      IR2 as the root.

   *  When BIER is used in the multicast domain, IR2 should be
      responsible for the forwarding role and forward flow to ER.

   *  When P2MP TE tunnel or MLDP is used in the domain, LSP initiated
      from IR2 can be built and replace the LSP initiated from IR1.

   *  When a static multicast tree or SR P2MP policy is used in the
      multicast domain, the controller should build a new forwarding
      path with IR2 as the root to forward the multicast flow to ER.

Shepherd, et al.           Expires 6 May 2026                   [Page 6]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

4.  Stand-by Modes

   Detection and IR switching can be three modes: cold standby, warm
   standby, and hot standby.  When the three modes are used to protect
   IR, the transmission mode of multicast flow in the multicast domain
   is different, and the impact on the network is also different.

   When the multicast domain uses the PIM protocol to forward flow, ER
   will establish a multicast tree to BIR through signaling.  When the
   multicast domain uses BIER to forward flow, ER will notify BIR the
   request to receive multicast flow through the BIER overlay protocol.
   When the multicast domain uses P2MP TE or MLDP to forward flow, a
   multicast forwarding channel is established from BIR to ER.  The PIM
   multicast tree with BIR as the root and the P2MP TE or MLDP tunnel
   from BIR to ER can also be established in advance, and ER directly
   notifies BIR to use the multicast tree or tunnel for forwarding.

4.1.  Cold Standby Mode

   In cold standby mode, ER selects a SIR (e.g. IR1 in Figure 1) as the
   SIR and signals it to obtain the multicast flow.

   When ER finds that it cannot receive the flow from IR1 through the
   detection means in Section 5, ER signals IR2 to obtain the multicast
   flow.

   *  For IR, IR (including SIR and BIR) only performs the normal
      operation of forwarding the flow according to ER request.

   *  For ER, ER must select an IR as the SIR and signal it.  When the
      SIR fails or the path between SIR and ER fails, ER must signal BIR
      to obtain the flow.

   *  For intermediate routers, they know nothing about the role of IR,
      they only forward packets.  There is no duplicate packets in the
      domain.

   In this scenario, the BIR does not need to detect the status of the
   SIR.  During the IR switching process, packet loss may occur because
   of the need for signaling interaction.  For example, slow convergence
   due to PIM join/prune signaling, BIER overlay signaling, etc.  Even
   if a PIM multicast tree or P2MP TE/MLDP tunnel is established in
   advance, packet loss may still occur.

Shepherd, et al.           Expires 6 May 2026                   [Page 7]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

4.2.  Warm Standby Mode

   In warm standby mode, the ER will signal to the SIR and BIR, such as
   IR1 and IR2 in Figure 2, that it needs to receive flow.  The SIR
   (such as IR1) forwards the flow to the ER.  The BIR (such as IR2)
   must not forward flow to the ER before the SIR fails.  The BIR can
   detect the SIR status by the method described in Section 5, and
   automatically forward flow to the ER when the SIR fails.

   *  Normally, the SIR forwards flow to the ER.  When the SIR fails or
      the path between the SIR and the ER fails, the BIR must start
      forwarding flow to the ER.  The BIR can detect node failures in
      the SIR using the method described in Section 5, but may lack the
      method to detect path failures from the SIR to the ER.

   *  The ER does not distinguish between the SIR and the BIR.  The ER
      only signals to both that it needs to receive a certain flow.

   *  For the intermediate routers, they do not know the difference
      between the IRs, and they are only responsible for packet
      forwarding.  There are no duplicate packets in the domain.

   When the BIR detects the SIR failure and starts forwarding flow,
   packet loss will occur during the failover.  To restore traffic as
   quickly as possible when the SIR fails, the BIR and SIR may need to
   synchronize multicast stream information.

   In some deployments, the SIR and BIR may be responsible for different
   multicast flows to share the load.  For a certain multicast flow, the
   SIR may be IR1, and for another multicast flow, the SIR may be IR2.
   For example, IR1 sends some multicast flows to ERs and IR2 sends
   other multicast flows to ERs.  Another possible deployment is that
   two IRs can be responsible for different ERs for the same multicast
   flow.  If IR1 detects a failure between IR1 and ERs, IR1 may notify
   IR2 to forward flow to these ERs.  In this case, to quickly restore
   traffic when a SIR fails, in addition to the multicast flows
   information managed by the SIR, the ERs information managed by the
   SIR must also be synchronized.

4.3.  Hot Standby Mode

   In hot standby mode, the ER signals both IRs that it wants to receive
   a certain flow.  Both IRs send flows to the ER.  The ER must discard
   duplicate flows from one of the IRs.  In this case, there is no SIR
   or BIR.  Only the ER knows which IR is the SIR.

Shepherd, et al.           Expires 6 May 2026                   [Page 8]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

   *  In this mode, the IR does not need to know the role of the SIR or
      BIR, IR only forwards the flow based on the request received from
      the ER.

   *  ER will send flow reception signals to both IRs and discard the
      duplicate flow from the backup BIR when it receives a duplicate
      flow.  After switching the ER receives and forwards the flow from
      the BIR.  It should be noted that the ER may choose different SIRs
      or BIRs for different multicast flows.

   *  Intermediate routers do not know the role of the IR, they only
      forward packets.  There are duplicate packets within the domain.

   In this mode, BIR does not need to detect the status of SIR.  Since
   duplicate flow packets arrive at ER, although packet loss may occur
   when ER switches to receive and forward flow from BIR, the packet
   loss is very small compared to the previous two modes.

   To quickly detect SIR faults, the ER can use the BFD mechanism
   defined in [RFC5880] to monitor the SIR status.  The SIR can also use
   the mechanism defined in [RFC8562] to send BFD packets, allowing the
   ER to monitor the SIR status as well.  With the BFD mechanism, zero
   packet loss may be achieved during switching.

4.4.  Summary

   The following table is a simple comparison of the three modes.  "SIR
   failover" means that the SIR fails or the path between the SIR and
   the ER fails.

   +==============+==================+===============+=================+
   | role         | Cold Mode        | Warm Mode     | Hot Mode        |
   +==============+==================+===============+=================+
   | IR           | Forwards flow    | Acting as     | Does not need   |
   |              | based on ER's    | either SIR or | to know SIR     |
   |              | request.         | BIR, BIR must | or BIR role,    |
   |              |                  | not forward   | just forwards   |
   |              |                  | flow to ER    | flow based on   |
   |              |                  | until SIR     | ER's request.   |
   |              |                  | fails over.   |                 |
   +--------------+------------------+---------------+-----------------+
   | ER           | Must select an   | Does not      | Signals both    |
   |              | IR as SIR to     | select SIR or | SIR and BIR.    |
   |              | signal request,  | BIR, just     | Drops           |
   |              | signals BIR to   | signals both  | duplicate       |
   |              | request flow     | of them.      | flow from BIR   |
   |              | when SIR fails   |               | until SIR       |
   |              | over.            |               | fails over.     |

Shepherd, et al.           Expires 6 May 2026                   [Page 9]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

   +--------------+------------------+---------------+-----------------+
   | Intermediate | Know nothing     | Know nothing  | No knowledge    |
   | routers      | about SIR or     | about SIR or  | of SIR or       |
   |              | BIR.  Do not     | BIR.  Do not  | BIR.  Forward   |
   |              | forward          | forward       | duplicate       |
   |              | duplicate flow.  | duplicate     | flow.           |
   |              |                  | flow.         |                 |
   +--------------+------------------+---------------+-----------------+
   | Failover     | Has the longest  | Moderate      | Has the         |
   | time         | failover time.   | failover      | shortest        |
   |              |                  | time.         | failover        |
   |              |                  |               | time.           |
   +--------------+------------------+---------------+-----------------+
   | Control      | No additional    | There is      | ER has a        |
   | Plane load   | burden.          | additional    | special         |
   |              |                  | control plane | control plane   |
   |              |                  | burden        | processing      |
   |              |                  | between SIR   | process.        |
   |              |                  | and BIR.      |                 |
   +--------------+------------------+---------------+-----------------+
   | Typical use  | Non-real-time    | IPTV, etc.    | High-quality    |
   | cases        | large data       |               | live            |
   |              | synchronization. |               | streaming,      |
   |              |                  |               | virtual         |
   |              |                  |               | reality, and    |
   |              |                  |               | remote          |
   |              |                  |               | conferencing,   |
   |              |                  |               | etc.            |
   +--------------+------------------+---------------+-----------------+

                                  Table 1

   Cold standby mode is the easiest to implement, but has the longest
   convergence time.

   Warm standby mode has a moderate packet loss rate and convergence
   time, but it is difficult for BIR to know the path failure between
   SIR and ER.

   Hot standby mode has the lowest packet loss rate, but there is
   duplicated packet forwarding within the domain, which consumes more
   bandwidth.  For example, in the MVPN scenario, the hot root standby
   mode described in Section 5 [RFC9026] is the best recommended method
   for MVPN fast failover optimization.  There may be duplicated packet
   forwarding within the domain, which will be discarded according to
   the provisions of [RFC9026] Section 6 and [RFC6513] Section 9.1.

Shepherd, et al.           Expires 6 May 2026                  [Page 10]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

   For network administrators, if they want to deploy hot standby mode,
   they need to consider whether there is enough bandwidth in the
   network to accommodate duplicate traffic.

5.  Failure detection

   The IR node itself and the key forwarding link between IR and ER are
   factors that affect traffic forwarding within the multicast domain.

   In order to achieve fast switching, BIR can establish a forwarding
   channel with ER in advance and monitor the status of SIR.  When the
   SIR node fails, it will take over the work of SIR.  BIR can establish
   a BFD [RFC5880] session with SIR to detect the SIR status, or it can
   be detected by ping and other methods.  However, it should be noted
   that the detection between BIR and SIR does not represent the actual
   forwarding path status between SIR and ER.  When SIR is working
   normally, only the link between BIR and SIR fails, which may cause
   BIR to make wrong judgments and switch, thereby generating
   unnecessary duplicate flow.  In this case, ER must support selective
   reception and be compatible with IR switching errors.

   There may be problems with the forwarding path between SIR and ER,
   but the link between BIR and SIR is normal and cannot be detected by
   BIR.  Therefore, ER can also detect the forwarding path between SIR
   and ER and actively switch to BIR to forward flow when problems are
   found.  The detection between SIR and ER can be based on multipoint
   BFD [RFC8562].  When BIER is used to forward flow in the multicast
   domain, the detection between SIR and ER can also be based on BIER
   BFD [I-D.ietf-bier-bfd].  When MPLS is used to forward flow in the
   multicast domain, BFD [RFC5884] based on MPLS LSP can be used for
   detection.

   Different detection methods can be selected to meet different
   detection requirements.  For example, a BIR can directly use BFD-
   based detection [RFC5880] to detect the status of an SIR.  The SIR
   can use multipoint BFD [RFC8562] to send multipoint BFD packets to
   ERs and the BIR.  In this way, both the BIR and the ER can detect the
   status of the SIR and the path status between the SIR and themselves.
   Network administrators can choose the appropriate monitoring method
   based on monitoring needs and device support.

Shepherd, et al.           Expires 6 May 2026                  [Page 11]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

6.  Deployment Considerations

   In general, Hot Standby mode is recommended when multicast services
   are critical, packet loss needs to be minimized, and the network
   bandwidth can accommodate repeated traffic.  Cold Standby mode can be
   deployed when multicast switchover time is sufficient and packet loss
   of at least a few seconds can be tolerated.  If the acceptable packet
   loss and switchover indicators fall between the two, Warm Standby
   mode can be deployed.

   Services that are sensitive to packet loss may include high-quality
   live streaming, virtual reality, and remote conferencing, etc.  For
   these scenarios, the Hot Standby mode is more suitable.  Warm Standby
   mode can be used for services with a relatively fixed topology, such
   as IPTV.  However, Hot Standby mode can also be used for high-quality
   IPTV services that are sensitive to packet loss.  Services that are
   more tolerant to packet loss may include non-real-time large data
   synchronization, such as data synchronization in CDN (Content
   Delivery Network) scenarios and operating system and other software
   upgrades.  For these scenarios, either the Cold Standby or Warm
   Standby mode can be used.

   Generally speaking, the scope of a multicast domain is the same as
   that of an AS domain or an IGP domain.  However, in some deployments,
   a multicast domain may span multiple IGP domains or AS domains.  This
   requires that the multicast-related unicast routes be synchronized
   across the entire domain, and then the corresponding multicast trees
   or tunnels, such as PIM, MLDP, and P2MP TE, be established.  BIER
   technology can also establish BIER domains across multiple IGP
   domains or AS domains.  Related implementations can refer to
   [I-D.ietf-bier-prefix-redistribute] and
   [I-D.ietf-bier-multicast-as-a-service].

7.  IANA Considerations

   This document does not have any requests for IANA allocation.

8.  Security Considerations

   This document adds no new security considerations.

9.  References

9.1.  Normative References

   [RFC4875]  Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
              Yasukawa, Ed., "Extensions to Resource Reservation
              Protocol - Traffic Engineering (RSVP-TE) for Point-to-

Shepherd, et al.           Expires 6 May 2026                  [Page 12]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

              Multipoint TE Label Switched Paths (LSPs)", RFC 4875,
              DOI 10.17487/RFC4875, May 2007,
              <https://www.rfc-editor.org/info/rfc4875>.

   [RFC6388]  Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B.
              Thomas, "Label Distribution Protocol Extensions for Point-
              to-Multipoint and Multipoint-to-Multipoint Label Switched
              Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011,
              <https://www.rfc-editor.org/info/rfc6388>.

   [RFC7450]  Bumgardner, G., "Automatic Multicast Tunneling", RFC 7450,
              DOI 10.17487/RFC7450, February 2015,
              <https://www.rfc-editor.org/info/rfc7450>.

   [RFC7761]  Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
              Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
              Multicast - Sparse Mode (PIM-SM): Protocol Specification
              (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
              2016, <https://www.rfc-editor.org/info/rfc7761>.

   [RFC8279]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
              Explicit Replication (BIER)", RFC 8279,
              DOI 10.17487/RFC8279, November 2017,
              <https://www.rfc-editor.org/info/rfc8279>.

9.2.  Informative References

   [I-D.ietf-bier-bfd]
              Xiong, Q., Mirsky, G., hu, F., Liu, C., and G. S. Mishra,
              "BIER BFD", Work in Progress, Internet-Draft, draft-ietf-
              bier-bfd-09, 25 August 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bier-
              bfd-09>.

   [I-D.ietf-bier-multicast-as-a-service]
              Zhang, Z. J., Rosen, E. C., Awduche, D. O., Shepherd, G.,
              Zhang, Z., and G. S. Mishra, "Multicast/BIER As A
              Service", Work in Progress, Internet-Draft, draft-ietf-
              bier-multicast-as-a-service-03, 6 February 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bier-
              multicast-as-a-service-03>.

Shepherd, et al.           Expires 6 May 2026                  [Page 13]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

   [I-D.ietf-bier-prefix-redistribute]
              Zhang, Z., Wu, B., Zhang, Z. J., Wijnands, I., Liu, Y.,
              and H. Bidgoli, "BIER Prefix Redistribute", Work in
              Progress, Internet-Draft, draft-ietf-bier-prefix-
              redistribute-09, 21 August 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bier-
              prefix-redistribute-09>.

   [I-D.ietf-pim-sr-p2mp-policy]
              Parekh, R., Voyer, D., Filsfils, C., Bidgoli, H., and Z.
              J. Zhang, "Segment Routing Point-to-Multipoint Policy",
              Work in Progress, Internet-Draft, draft-ietf-pim-sr-p2mp-
              policy-22, 4 September 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-pim-sr-
              p2mp-policy-22>.

   [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>.

   [RFC5884]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
              "Bidirectional Forwarding Detection (BFD) for MPLS Label
              Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
              June 2010, <https://www.rfc-editor.org/info/rfc5884>.

   [RFC6513]  Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
              BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
              2012, <https://www.rfc-editor.org/info/rfc6513>.

   [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>.

   [RFC9026]  Morin, T., Ed., Kebler, R., Ed., and G. Mirsky, Ed.,
              "Multicast VPN Fast Upstream Failover", RFC 9026,
              DOI 10.17487/RFC9026, April 2021,
              <https://www.rfc-editor.org/info/rfc9026>.

Authors' Addresses

   Greg Shepherd
   Cisco Systems, Inc.
   170 W. Tasman Dr.
   San Jose,
   United States of America
   Email: gjshep@gmail.com

Shepherd, et al.           Expires 6 May 2026                  [Page 14]
Internet-Draft   Multicast Redundant In-Router Failover    November 2025

   Zheng Zhang (editor)
   ZTE Corporation
   Nanjing
   China
   Email: zhang.zheng@zte.com.cn

   Yisong Liu
   China Mobile
   Beijing
   Email: liuyisong@chinamobile.com

   Ying Cheng
   China Unicom
   Beijing
   China
   Email: chengying10@chinaunicom.cn

   Gyan Mishra
   Verizon Inc.
   Email: gyan.s.mishra@verizon.com

Shepherd, et al.           Expires 6 May 2026                  [Page 15]