The invention relates to a system and method for efficiently distributing
multicast messages within computer networks configured to have one or more
virtual local area network (VLAN) domains. A multicast network device
(MND), having a plurality of interfaces, includes a multicast controller
for efficiently distributing multicast messages among subscribing entities
associated with various VLAN domains. The multicast controller, which is
in communicating relationship with the interfaces, includes a VLAN
assignment engine for assigning responsibility for the VLAN domains to the
extent there are multiple MNDs. The multicast controller also accesses a
multicast tag source to establish a plurality of novel VLAN tags for
efficiently distributing multicast messages, including a sub-regional
Multicast VLAN Identifier (MVLAN-ID) that encompasses all of the VLAN
domains for which the respective MND is responsible, and one or more
color-limited MVLAN-IDs that encompass all of the VLAN domains for which
the MND is responsible except for one. The multicast controller then tags
multicast messages with its sub-regional or a color-limited MVLAN-ID
depending on whether the message is considered internal or external by the
respective MND. The tagged messages are then forwarded for distribution to
the subscribers associated with the various VLAN domains.
