Border Gateway Multicast Protocol (bgmp)

Last Modified: 2004-06-07


Bill Fenner <>
Bradley Cain <>
Jeremy Hall <>

Routing Area Director(s):

Bill Fenner <>
Alex Zinin <>

Routing Area Advisor:

Alex Zinin <>

Mailing Lists:

General Discussion:
To Subscribe:
In Body: subscribe bgmp

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

No Current Internet-Drafts

Current Request For Comments

Border Gateway Multicast Protocol (BGMP): Protocol Specification (RFC 3913) (97443 bytes)