MBONE: Multicasting Tomorrow's Internet
In 1993, a computer program called Mosaic changed all that. Mosaic is a browser -- a program that allows users to use the Internet's World Wide Web. For the first time, true multimedia -- the mixing of various media such as text, images, sounds, and movies -- came to the Internet. Today, not only can you download those sorts of files, but you can also experience them while you are online. And, if you have anything to say, you can even present your information, complete with mixed media, on your own Web page.
The World Wide Web continues to grow in popularity, but most of us have limited bandwidth resources. We use poky 9600 bps and 14.4 Kbps modems to send and receive data, but in the world of full multimedia we're going to need much faster access. After all, 14.4 Kbps means 14,400 bits of information every second, and even with good data compression technology, we're lucky to hit 38,800 bits per second regularly. At these speeds, video or audio files that are more than a few minutes long can take an hour or more to transfer to a PC, so if you're waiting to see Gone with the Wind or hear Wagner's entire Ring cycle, forget it. Even users who are lucky enough to access the Internet with a 28.8 Kbps modem get tired of waiting for things to download.
As a result of this bottleneck, most people get only text and graphics files from the Web. Text and still image files are generally small, so you don't need to wait too long to view them, but anyone who has waited for a graphically heavy Web site, such as Time Warner's Pathfinder, soon realizes how frustrating even this experience can be. Although audio and animation are both possible on the Web, you need a much faster connection (or the patience of a saint) to send and receive the huge audio and video files that would enable you to take full advantage of Internet multimedia.
Figure 1-1: Time Warner's Pathfinder Web site -- a great resource, but the images can make it slow going
On the Internet, and typically in real life, new technologies are first available to a core group of inventors and experimenters. If the new technology is good enough, or interesting enough, or worthwhile enough, word gets out. Other folks begin to hear about the wonders of the new technology, and they want to try it. They find out what they need, and then they spend whatever time and money is necessary. Slowly, the technology gains wider and broader acceptance, with more and more people taking part, until at last it becomes so common that it's practically a household word. Consider, for example, electronic mail. Or the World Wide Web. Or the waffle iron.
What's interesting about the Internet these days is that new technologies don't get much of a experimental period. The Net had more than a decade to shake itself out, from the time of its inception in 1969 to the beginnings of its widespread use in the early 1980s. After that, especially beginning in the late 1980s, new technologies started moving from someone's brain to common use in a matter of a couple of years or even less. Mosaic, the famous World Wide Web browser, is an excellent example. First introduced in February 1993, and solely for UNIX's X Window platform, Mosaic became an important program for thousands of UNIX, Windows and Macintosh users by the end of 1993, and it became probably the most written-about computer program in the world by the middle of 1994. If you want to invent an Internet technology today, you'd better plan to introduce it less than a year after you start working on it, or the technology will likely be out of date by the time it hits the Net.
Nevertheless, important technologies take time to develop. Sometimes, a technology is so complex that years of research are needed to get it to work at all. Other times, the technology demands so much of related technologies that only a few people in the world have the equipment necessary to even get an inkling of what the technology is about. Over the past few years, something called the MBONE has been making its way onto the Internet slowly and experimentally. But its use is about to increase exponentially, because even those of us who today rely on mere modems will soon have access to the technologies that are necessary to bring the MBONE into our homes and offices.
Today, "regular Internet users" are at the cusp of a new multimedia revolution. Users who are pushing the limits of a 14.4 Kbps connection can already use some cool new multimedia tools (some of which are discussed in Chapter 3). In the coming months, true multimedia will become more commonplace for "regular users" as bandwidth limitations decrease and as hackers continue to improve compression methods for stuffing more information down that thin 14.4 Kbps link. Then, too, 28.8 Kbps modems will soon be cheap enough to replace the 14.4's completely, helping to ease the data bottleneck even further.
What is bandwidth?Throughout this book, we bandy about the word bandwidth. Simply, bandwidth is a measurement of how much information can be transmitted between two points in a given period of time.
If you own a modem, you are probably already familiar with bandwidth to some extent. Your modem operates at a certain maximum speed -- the speed of a modem is it's bandwidth. A 2400 bps modem can transmit 2400 bits per second (bps) of information. (A bit, by the way, is the smallest particle of information that a computer can handle -- a single digit: 1 for "on" and 0 for "off.") A 2400 bps modem can transmit and receive approximately 240 characters each second. (A character is a single letter, number, or punctuation mark.)
If you use a 2400 bps modem, you may feel that it's a bit on the sluggish side. Indeed, faster modems -- modems with much greater bandwidth capability -- are available. The authors use modems that work at 28,800 bits per second. At about 2,880 characters each second, those bad boys work 12 times faster than a 2400 bps modem.
Vanilla modems are not likely to go much faster than 28.8 Kbps (kilobits, or thousands of bits per second) because the phone system that they're designed to work with can't handle much faster data reliably. However, there are a variety of ways to move information at faster speeds. For example, a special data line called a T-1 can move 1,544,000 bits a second. A
runs at 28 times the speed of a T-1.
Most of us will never need the kind of bandwidth that a T-3 line provides, but a variety of systems can provide a happy medium of Internet bandwidth. One system, called ISDN, enables you to pump information around at a crisp 128 Kbps. ISDN equipment and service are more expensive than a plain old phone line and modem, but prices are dropping.
It can be hard to digest all those bits and bytes and get a clear picture of how much bandwidth we're really talking about. The authors sometimes use a less established measurement of bandwidth: bibles per second. Bibles per second gives us something we can readily understand: How long does it take to transmit the King James version of the Bible? Well, the text of the Bible is just under 5MB in size. A 2400 bps modem requires more than 4.5 hours to transmit that size file. A 28.8 Kbps modem can duplicate the tome in about 23 minutes. A 128 Kbps ISDN link that's running at full tilt can do the job in 5 minutes. A T-1 line can do it in 25 seconds, a T-3 in less than a second. (The figure will give you a better idea.)
You can see why greater bandwidth is a necessary (and somewhat addictive) thing: Although most of us don't download a copy of the Bible on a daily basis, Internet users think nothing of receiving a 5MB program from an FTP site or sucking down 5MB of graphics from the World Wide Web.
Using a bigger pipe (more bandwidth) is one way to speed things up. Another solution is to use compression to reduce the size of the file that's being transmitted. Many modems include a built-in compression feature. Two similarly-equipped modems automatically compress data before sending it and then decompress it again after receiving it. As a result, more information can be transmitted more quickly. Text compresses rather well: A 5MB Bible, when compressed, requires only about 1.5MB of bandwidth. Unfortunately, some other types of data -- such as certain graphic file formats and files that are already compressed (for example, .GIF images and .ZIP file archives) -- can't be compressed much further, so your modem's compression doesn't save additional bandwidth.
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