MBONE: Multicasting Tomorrow's Internet


The history of 20th century communications begins, quite probably, in the latter part of the 19th century. After a series of experiments conducted by a number of people, Alexander Graham Bell put together a device that would become the telephone. Of all the technological inventions of the past 150 years, surely none has affected the course of human communications as much as this one, at least not in the nations where telephone service has become a sine qua non of day-to-day existence. Through this one device, businesses thrive, relationships evolve, people's lives are both made and destroyed. It is as difficult for most North Americans to imagine a world without telephones as it is for them to imagine a world without electricity. The two, it seems, go hand in hand.

Since the middle of this century, the telephone has taken on a new role. Where previously phone lines were relied on to transmit voice messages, they have since become the primary means for transporting digital data as well. When you log on to your Internet account and download a file from an FTP site, you are using the same telephone system you use when you call your loved ones from the other side of the continent. The difference is that the latter scenario transmits analog signals, while the former transmits digital signals. Since the phone system is an analog transport system (fiber optics technologies are changing all this), the digital signals from your computer have to be changed into analog signals for transmission to occur. The device that does this is the modem (modulator-demodulator), a device that has become almost as ubiquitous as personal computers themselves.

There's a problem with the combination of modems and phone lines. They aren't very fast. That is, they allow data to be transferred at a limited rate, and the 28.8 kbps (kilobits per second) modem is approaching the analog phone system's technological limit. (Probably. But that's what they said about 2400 bps modems, too...) By compressing the data it it sending and receiving, your modem can reach an effective transmission speed of 115,000 kbps, but in practice this is rarely achieved. Even if it were, it would be too slow to handle the huge quantities of data necessary for the transmission of audio and (especially) video files, so from the standpoint of the MBONE the modem isn't an issue. Far greater speeds are needed, along with increasingly effective data compression technologies.

But the telephone-modem combination has provided the basis for theorizing about the MBONE or any other kind of digital communications technology. With the telephone, long-distance real-time human communication became possible (telephone means to speak far), and with the modem, direct transfer of data from one machine to another, by means of the widespread global telephone system, also became possible. The main point here is that people from all over the world could communicate with each other or exchange information with each other, and they began to expect to do so more or less instantaneously. People could pick up the phone and say hello from one side of the world to the other, or they could log into their accounts and transfer files to machines every bit as far away.

Or, by using these same computers and these same phone lines, they could replace telephonic communication with computer-based communication. To do this, they used the messaging capabilities of their networked computers -- electronic mail, newsgroups, or various forms of network "chat." Electronic mail and newsgroups (the latter primarily through a sub-network called Usenet) weren't real-time communications; you composed and sent your message, then waited for the recipients to read it, compose a reply, and send it back to you.

As for network chat, which allowed real-time communications between two Internet users, or the more popular Internet Relay Chat (IRC), in which several people linked themselves together simultaneously and communicated that way, the major problem was the fact that communicating was done through typing. To see how significant this problem is, arrange with a friend to use a chat program such as UNIX's talk while you're logged on together, and try to carry on a "conversation" through typing. You'll quickly discover that the typing itself becomes a topic of conversation, and that for most people typing impedes the actual communication. Then, for a really fascinating time, hook up to an IRC channel and carry on a conversation with not just one, but potentially a dozen or so other users, all trying to make themselves heard, with several different conversations going on at once. It's a lot like a loud, active family dinner conversation, except that our eyes are much less effective than our ears at filtering through the din.

Over the years, electronic mail and newsgroups haven't changed much. Nor, for that matter, has postal mail. With their capabilities essentially at their limit, and with the telephone limited by the fact that conversations are timed for the sake of charging money (we've all experienced the nearly debilitating effect of that imaginary clock ticking while we're talking on the phone), new communications mechanisms became desirable. Then, too, there was the advent of videoconferencing, in which people from distant locations set up equipment and conducted live conversation with a full video complement. That meant that you could see each other while you talked, and therefore you could draw diagrams, demonstrate things, and otherwise make use of the sense of sight, something that the telephone and its associated audioconferencing (i.e., conference calls) didn't allow. The problem with videoconferencing was that it was (and is) extremely expensive, prohibitively so for anyone outside a very well funded organization.

During the past few years, two communications methods have appeared on the Internet, neither of them new but both promising to be revolutionary. The first is real-time audio communication; the second is real-time video communication. Real-time audio communication effectively means the ability of two Internet users to converse with each other by voice and in real-time -- in other words, the ability to use the Internet like a telephone. The demands of real-time video over the Internet are much higher, and until a few years ago this technology was considered impossible. The MBONE is the primary means of effecting real-time video, and its research was begun in earnest, in fact, nearly four years ago.

The first basis for the coming of the MBONE, then, is the constantly growing need for more and better forms of human communication.

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