Subject: WG Review: Border Gateway Multicast Protocol Working Group (BGMP)

From: The IESG <[email-masked]>
Date: Fri, 11 Jun 1999 13:30:05 -0400

A new IETF working group has been proposed in the Routing Area.
The IESG has not made any determination as yet. 

The following Description was submitted, and is provided for
informational purposes only:

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.