Border Gateway Multicast Protocol (bgmp)

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NOTE: This charter is a snapshot of the 59th IETF Meeting in Seoul, Korea. It may now be out-of-date.

Last Modified: 2003-10-30

Bill Fenner <>
Bradley Cain <>
Jeremy Hall <>
Routing Area Director(s):
Bill Fenner <>
Alex Zinin <>
Routing Area Advisor:
Alex Zinin <>
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Description of Working Group:
As IP multicast is being more widely deployed and used, the existing multicast routing algorithms have demonstrated several limitations which make them unsuitable for deployment globally or among multiple provider domains. Protocols like DVMRP and PIM Dense Mode that rely on broadcasting and pruning leave state in parts of the network that are not on the multicast delivery tree. Protocols like CBT and PIM Sparse Mode use a centralized resource to learn of multicast sources. Service providers are reluctant to maintain state for multicast groups that have no receivers in their domain or use a centralized resource in another domain that they cannot control.

BGMP is a scalable multicast routing protocol which addresses these problems. Like CBT and PIM Sparse Mode, BGMP chooses a global root for a delivery tree. However, the root is a domain, not a single router, so if there is any path available to the domain connectivity can be maintained. BGMP builds a bidirectional, shared tree of domains. Similarly to the unicast EGP/IGP split, BGMP is used as the inter-domain or external protocol, while domains can run any multicast IGP internally (such as CBT or PIM Sparse Mode), and can build source-specific shortest-path distribution branches to supplant the shared tree where needed.

The BGMP working group is chartered to complete the protocol specification and follow it through the Internet standards track. It will also help to design a transition mechanism from MSDP (the Multicast Source Distribution Protocol, an interim interdomain solution that is unlikely to scale for the long term) to Internet-wide BGMP.

Goals and Milestones:
Nov 99  Develop security portion of spec
Nov 99  Consider monitoring and measurement (e.g. multicast traceroute) and evaluate support for existing and/or new monitoring and measurement tools and protocols.
Nov 99  Evaluate interoperability with multicast IGPs in more detail and identify any relevant optimizations and/or implementation issues.
Nov 99  Evaluate forwarding rules and transient behavior under a wide range of topologies under simulation
Done  Resolve multi-access LAN forwarding mechanisms
Mar 00  Produce revised protocol specification based upon simulations and evaluations
Mar 00  Produce initial version of MIB
Mar 00  Design a transition architecture from PIM-SM/MSDP to BGMP
Jul 00  Guide the development of a reference implementation
Jul 00  Oversee interoperability experiments
Nov 00  Finalize MIB
Nov 00  Produce applicability document
Jul 03  Submit final version of protocol specification Internet Draft
  • - draft-ietf-bgmp-spec-06.txt
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