The MBone (Multicast backBONE) is an experimental virtual network that is superimposed upon the Internet. The MBone provides efficient real-time distribution of data to multiple destinations using IP multicast. Limitations of the current Internet restrict the quality of received audio and video, though at their best, both audio and video are quite adequate for the purposes of a conference (video rates generally do not exceed 8 frames per second, and audio quality is equivalent to a good telephone connection). MBONE teleconferencing will improve dramatically in future with the widespread deployment of technologies such as ATM, which allows the specification of the level of audio/video performance.
The MBONE has been in existence since early 1992, and originates from experiments during IETF (Internet Engineering Task Force) meetings in which live audio and video were transmitted around the world. The MBONE today is used by hundreds of researchers for developing protocols and applications for group communication. Multicast is used because it provides one-to-many network delivery services for applications such as videoconferencing and audio that need to communicate with several other hosts simultaneously.
IP multicasting was developed by S. Deering of Xerox Palo Research Center and is supported by numerous workstation vendors including SUN, Silicon Graphics, Digital and Hewlett Packard. World-wide installation of high bandwidth Internet backbone connections, amd the widespread availability of workstations with adequate processing power and built-in audio and video capability are now starting to make widescale MBONE conferences possible.
The MBONE uses a network of routers that can support multicast. MBONE is also augmented with "tunnels". Tunneling is a scheme to forward multicast packets between the islands of MBONE subnets.
The MBONE topology and the scheduling of multicast sessions must be actively managed by the MBONE community to minimize congestion. Special programs are announced in advance on an MBONE event mailing list (rem-conf@es.net).
MBONE researchers are developing new applications that typify many of the goals associated with an "information superhighway". MBONE session availability is dynamically announced using a tool called sd (session directory). Sd is also used for launching multicast applications. Video, audio and a shared whiteboard are the principal MBONE applications, provided by S. McCanne and Van Jacobson of LBL. Other tools available include: ivs (audio and video conferencing developed by T. Turletti in INRIA), and nv (network video tool from Xerox PARC). A high resolution, low bandwidth image server providing live images of the earth from geostationary satellites can be viewed using the image multicaster client imm.
Many of the most exciting events on the Internet appear first on the MBONE. Conferences on supercomputing, IETF, scientific visualization and many other topics have appeared. The MBONE community is active and open. Work on tools, protocols, standards, appeared and events is very much a cooperative and international effort. MBONE stands for powerful concepts and powerful tools that tremendously extend our ability to communicate and collaborate. MBONE has already changed the way people work and interact on the net.
Anyone wishing to participate on the MBONE must make advance preparations: in particular, they must set up a local multicast router and a multicast capable connection or tunnels to a multicast router already on the MBONE. The local connection to the Internet must be sufficiently fast, and the requisite software must be installed (this generally requires a UNIX graphical workstation although tools for PCs and MACs are starting to appear).
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Created: 22 February 1996
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