Welcome to the home page for technical information about IP multicast from the IP Multicast development and development testing groups. Is is targeted for customers that are participating in Cisco Systems multicast deployment activities, early field testing (EFT) or beta testing.

Go to the Cisco IOS Source Specific Multicast (SSM) Homepage




Configuration note about Microsoft uPNP group in Config Notes Directory


New Added directories and files for Networkers presentations from 2001-2003

UpdatedConfiguration note: Equal Cost Multipath support for IP Multicast
New Configuration note: Configuring multiple Static Mroutes for IPv4 in Cisco IOS
3/06/03 Updated Multicast support for MPLS/VPN (MVPN) section
New Configuration note: BSR RP election incompatibility with RFC2362
New Configuration note: IP Multicast, SSM and IP/TV version 3.4
Added information about the Cisco IOS MVPN  (Multicast VPN) solution.
New application note on IP Multicast Network Management - MIBs and Cisco IOS
11/13/01 New configuration note on IGMP timers.
11/04/01 New configuration note Understanding and using the "ip pim rp-announce-filter" command, updated Main List of Multicast Commands .
07/05/01 Added pointers to protocol Specifications (RFCs, Cisco implemented drafts, other protocols: AutoRP, CGMP, PIMv1)
06/25/01 Added several new pointers/files to Application and Configuration Notes, especially: Anycast-RP description and Using ip multicast rate-limit to police ip multicast traffic
06/18/01 Added presentation for UDLR to feature section.
04/09/01 Posted final PGM spec draft-speakman-pgm-spec-06.txt
02/27/01 Moved MPLS TE tunnel / IP Multicast interoperability description into Configuration Note: MPLS Traffic Engineering and IP Multicast Interoperability
02/27/01 Retired IP Multicast tagswitching note. See config-notes/historic/tagswitching.txt
11/29/00 Configuration Note:  IP Multicast Multipath configuration note
11/13/00 Updated Feature description / links for features to go into Cisco IOS 12.1(5)T:MSDP-MIB, RGMP, PIM-DM State-Refresh, UDLR Tunnel Enhancements and IGMP Proxy support and SSM with IGMPv3, IGMP v3lite and URD (see Cisco IOS SSM Homepage ).Note: CCO documentation links will become active once 12.1(5)T ships.
11/13/00 Added a link to the Interdomain Multicast Solutions Whitepaper for ISP Multicast configuration recommendations / examples.
11/13/00 Updated link to IP Multicast Homepage on CCO, - completely overhauled.
11/13/00 Added links to the Cisco IOS SSM Homepage for SSM, IGMPv3, IGMP v3lite, URD.
11/13/00 Updated IOS-Version/Feature information file Recommended IOS Images
10/23/00 Configuration Note: MSDP SA filter recommendations corrected / SSM range added.
08/11/00 Added HTML/graphical version of the IP Multicast Quickstart Configuration Guide whitepaper.
08/11/00 Added new Whitepaper: Internet Protocol (IP) Multicast Technology Overview.
08/31/00 Added two new Application Notes about CGMP Leave Processing and TTL Handling in Dense-Mode
08/18/00 Completely new Internal Multicast Training course material added. (Many new topics added.)
08/17/00 Added info about MSDP MIB support.
08/04/00 Added Multicast Voice over IP (MVoIP) aka 'Hoot & Holler over IP' information.
08/02/00 Corrected information about MSDP, put -02 spec up.
06/23/00 Added new Whitepaper, A Brief History on Internet Multicast.
06/19/00 Linked Networkers 2000 presentations.
04/10/00 Updated IOS-Version/Feature information file Recommended IOS Images
04/10/00 Posted latest PGM spec draft-speakman-pgm-spec-04.txt
03/30/00 Added 12.1 documentation links to features.
03/30/00 Updated PGM information (PGM host support introduced in 12.1(1)E)
03/29/00 New Feature released: RGMP - RouterPort Group Management Protocol (12.0(10)S/12.1(1)E)
03/27/00 Updated MRM links.
03/27/00 Tool: MMON, Multicast Management Tool from HP.
03/27/00 Configuration Note: Changed BGP/MBGP syntax for newer 12.0T, 12.1 versions of IOS
03/27/00 Added Multicast Troubleshooting Guide .
03/27/00 Corrected MIB files for 12.0T, 12.0S, 12.1 (MSDP flag added)
02/22/00 Added UDPTN feature links.
01/20/00 Updated MSDP links and information (drafts, CCO documentation).
12/10/99 Configuration Note: MSDP SA filter recommendations
11/23/99 Updated Bidir-PIM information.
11/23/99 Configuration Note:Tunneling IP Multicast through a PIX Firewall

See the Change Log for a complete list of changes.
IOS IP Multicast Documentation





  • Interdomain Multicast Solutions (November 2000, HTML)

  • This Interworking Solutions Guide is a hands-on description of the Cisco recommended configuration of IP Multicast services in typical ISP networks. It contains the complete Cisco IOS configurations for different simplified ISP networks and describes the solution strategies and effects of the configurations choosen. This is not a theoretical "could-be" paper, but it has been verified by actually setting up the complete configuration in a Cisco End-to-End test lab.
  • Internet Protocol (IP) Multicast Technology Overview (September 2000, HTML)

  • This whitepaper explains all the important concepts of IP Multicast: Addressing, IGMP (Version1, Version2), IP Multicast in switching (CGMP, IGMP Snooping), Source & Shared Multicast Distribution Trees, RPF-Checking, Routing Protocols (PIM Sparse-Mode, PIM-Dense-Mode), MBGP, MSDP, Anycast-RP, MADCAP, MZAP and PGM. This whitepaper is meant to give a basic understanding of these concepts without going into the details of actual configuration in Cisco IOS.

    Training Material


    Other documentation

    IOS Release Information



    IP Multicast features
    Note: References to CCO documentation may not always point  to the latest release for which a certain feature is documented. Then again, they may sometimes predate the documentation being placed on CCO and may thus temporarily point to NIL.
    Note: The features are listed in alphabetical order.


    Bidirectional PIM is an extension to the PIM suite of protocols that implements shared sparse trees with bidirectional flow of data. In contrast to PIM-SM, Bidir-PIM avoids keeping source specific state in router and thus allows trees to scale to an arbitrary number of sources.

    IGMP Proxy / Stub multicast routing.

    IGMP Proxy is the loosely used term to describe a feature, in which a router does not rely on PIM or other routing protocols to build multicast trees, but instead forwards/proxies IGMP messages from downtree to upstream routers. It is typically used in routers that can not use PIM.
  • Historically, Cisco IOS provides a limited subset of IGMP Proxy functionality through configuration combinations involving ip igmp helper-address and PIM-DM configuration with filtering.
  • Cisco IOS 12.1 documentation for Stub multicast routing configuration.
  • Cisco IOS 12.1(5)T introduces flexible IGMP Proxy functionality, extending on this basic configuration mechanisms.
  • Cisco IOS 12.2 UDLR/IGMP Proxy Configuration Guide
  • Cisco IOS 12.1(5)T UDLR Tunnel enhancement and IGMP Proxy Feature documentation on CCO.
  • IGMP v3

    IGMP v3 is the newest version of the IGMP protocol with which hosts signal to routers the multicast traffic they want to receive. Version 3 of this protocol adds support for host specific membership reports which amongst other benefits enables SSM. In Cisco IOS, IGMP v3 is part of the SSM solution.
  • Please see the Cisco IOS SSM Homepage for further information.
  • IGMP v3lite

    IGMP v3lite is a Cisco specific SSM transition solution toward IGMPv3 for application developers and users that have to rely on host operating systems that do not yet support IGMPv3. Using IGMP v3lite, application developers can support IGMP v3 for SSM before the host supports IGMP v3 itself in the operating system. IGMP v3lite works together with Cisco IOS routers in the network.
  • Please see the Cisco IOS SSM Homepage for further information
  • MBGP

    Multicast BGP (MBGP) is an application of RFC2283. MBGP is run between BGP peers to exchange a second set of IP routes which are used for IP multicast reachability. For PIM, MBGP is the preferred solution to achieve non-congruent multicast and unicast topologies. MBGP used together with MSDP is the current deployment solution to connect PIM-SM domains.

    MDS (MDfS)

    Multicast Distributed  fast Switching (MDS, or better MDfS) incorporates support for distributed switching of multicast packets at the line cards (VIPs on Cisco-75xx and line cards on the GSR). The switching function is always performed at the line cards so that the Route Processor is used only to do route processing.


    The IP Multicast Multi Layer Switching (MMLS) feature provides high-performance, hardware based, Layer 3 switching of IP multicast traffic for Catalyst 5000 series LAN switches connected to an IOS based router and for Catalyst-6000 series LAN switches with a PFC/MSFC.


    The Multicast Reachability Monitor (MRM) feature is a management diagnostic tool that provides network fault detection and isolation in a large multicast routing infrastructure. It is designed to notify a network administrator of multicast routing problems in near real time.


    Multicast Source Discovery Protocol is a mechanism to exchange (S,G) information between RPs in PIM-SM domains. It can not only be used in interdomain applications with or without MBGP but also in intradomain applications to achieve RP resilience.

    MVoIP - Hoot & Holler over IP

    Cisco MVoIP (Multicast Voice over IP) is a Voice over IP application of IP Multicast. It uses Ciscos VoIP technology over IP Multicast to create a replacement for the traditional 'Hoot & Holler' networks used in brokerage firms. Hoot & Holler systems provide continuous voice conference functionality between sets of telephones at different sites (continuously on, no dialing).

    MVPN - Multicast VPN (Virtual Private Network)

    Cisco's MVPN (Multicast VPN) solution allows for the transport of ip multicast traffic from VPN networks across a provider VPN backbone using ip multicast traffic with multicast-in-multicast encapsulation. The current feature is seamlessly integrated into the Cisco IOS MPLS-VPN solution. The MVPN solution utilizes GRE encapsulation with unique multicast distribution tree (MDT) forwarding to realize the true scalability of native ip multicast in the core network.
    • Support for MVPN was introduced for Cisco 7500 and Cisco-7200 with Cisco IOS 12.2(13)T and Cisco IOS 12.0(23)S. Support for Cisco-7500 is in MDFS (eg: distributed switching).
    • Support for MVPN hardware forwarding on Cisco-10000 series router was introduced with Cisco IOS 12.0(23)SX (same features as 12.0(23)S). 
    • Support for MVPN on Cisco-12000 and Cisco-7600 series routers is in EFT. Please contact us if you are interested.
    • An MVPN capable IOS feature is only required for PE routers, not for P routers. P routers can run any supported Cisco IOS image that supports unicast MPLS and IP multicast routing.
    • 12.2(13)T and 12.0(23)S configuration guides for MVPN.
    • Networkers Multicast VPN Introduction and Overview Presentation (HTML, PDF)


    Pragmatic General Multicast (PGM) is a reliable multicast transport protocol for applications that require ordered, duplicate free, multicast data delivery from multiple sources to multiple receivers. PGM router assist is the function executed by routers to allow PGM application to scale better. PGM Host is the function executed by hosts running PGM.


    RouterPort Group Management Protocol (RGMP) is a protocol between PIM-SM routers and RGMP supported layer 2 switches to reduce flooding of IP multicast traffic in switched transit networks on the PIM-SM router ports supporting RGMP. It is supplementing IGMP snooping which only reduces flooding to host ports.


    Source Specific Multicast (SSM) is an extension to the IP Multicast service, with the intend to be better and more easily deployable to and to solve crucial issues like address management and interdomain routing for Internet Broadcast style applications.


    State-refresh is an extension to PM Dense Mode (PIM-DM) protocol. It uses a heartbeat kind of mechanism to avoid period flood and prune behavior.


    Unidirectional link routing (UDLR) provides a way to forward multicast packets over a physical unidirectional interface (such as a satellite link of high bandwidth) to stub networks that have a back channel. There are two mechanisms: UDLR-Tunnels which applies to unicast and multicast, and IGMP-UDR, which only applies to multicast.


    UDP TelNet (UDPTN) is a feature in IOS that provides the ability to encapsulate asynchronous data into UDP packets, and then unreliably transmit this data to one (unicast) or more (multicast, broadcast) IOS routers where it is converted back to asynchronous data on a serial interface.


    URD is a Cisco specific SSM transition solution that allows content providers to provide content via SSM even when using legacy applications that do not support IGMPv3 or IGMP v3lite. URD relies on URLs provided by the content server that are intercepted by the last-hop router to transmit the source address information. URD is completely transparent to the application and can thus be provided for wthout any changes to the host software. URD works together with Cisco IOS routers.
  • Please see the Cisco IOS SSM Homepage for further information.
  • Other IP Multicast information sources

    Other Cisco Sites related to IP Multicast

    IETF links on IP Multicast

    Other IP Multicast related links outside Cisco

    Support and Contact Information


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    Cisco IP multicast related mailing lists

    Owners: IP Multicast Development & Dev/Test Groups