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How a Network Supports IP Multicast 337
Internet Support for
IP Multicast
The MBONE is the Internet’s experimental multicast backbone network. It
is an interconnected set of Internet routers, subnetworks, and tunnels
that support the delivery of IP multicast traffic.
The MBONE was first configured in 1992 as a test zone to enable IP
multicast applications to be deployed without waiting for multicast
routers to replace unicast routers across the entire Internet. The MBONE is
actually a virtual network located within portions of the physical Internet.
Its construction reflects several multicast zones connected together via IP
multicast tunnels. When it was created in 1992, the MBONE spanned
four countries and 40 subnetworks; today it spans over 25 countries and
thousands of subnetworks.
You can connect to the MBONE through most Internet service providers
(ISPs). You can use it to test multicast applications and technology or to
connect private multicast LANs. Some organizations broadcast public
information over the MBONE; examples include IETF (Internet Engineering
Task Force) meetings and NASA (National Aeronautics and Space
Administration, United States) space shuttle launches.