Obligatory Dilbert Management Bashing Comic Strip
Asynchronous Transfer Mode (ATM) is a new communications switching technology that will allow instantaneous switching of very high bandwidth transmissions. The obvious questions are: "What is a very high bandwidth transmission and why do I care?" We'll attempt to explain:
Most PCs are capable of using modems rated at 33.6 kilobits per second of transmission. Kilobits is just "thousands," so these modems are communicating (transmitting or receiving) 33,600 bits of compressed information per second; however, most modems in service are really carrying only 14,400 actual bits per second and slower. "So what," you say. Well, here are the consequences of this level of technology: while these speeds are just fine for carrying text and similar types of single character data, these speeds are not adequate for carrying anything else. You have all probably experienced the long delays required to download a single picture when using the Internet. If you haven't, you can readily experience this type of delay by using a modem to pull up a web page containing lots of graphics. The time required to access the page is often greater than 30 seconds. This delay is largely a function of transmission speed. So now you should ask: "Great, then how fast is fast, and what can I get with it?"
Fast is around 50 MILLION bits per second - 1800 times faster than 28.8 modems. If you could communicate at this speed, what would you achieve? You would possess full motion video, or nearly instantaneous high definition picture transmission. You would also have the capability to download large files, even whole programs, in just a few seconds. Currently, you are getting this volume of information (50 million bits per second) from your cable TV company's network. They use it to transmit the 50 or so TV channels of entertainment to your television. The problem with this type of network is that everyone connected to the Cable TV network gets the exact same information (channels) as everyone else. As long as you never require anything different than what the other people on your network want, then you should be satisfied with your current arrangement. However, most people want information tailored to their needs, not the needs of everyone else.
Suppose you want to download and watch any movie of your choice at any time. Suppose you want to get full motion video from the Internet. Or you want to make a video telephone call to your mom. Or assume that you want to record a specific program from a specific channel (selected from one of the of 500 channels that will be made available to you). If you want the flexibility to get these services, then you will need high speed communications which are "switched," or directed, to and from the destination you choose.
The solution which can provide this type of communication is a connection to the world over high speed transmission lines, which goes through an ATM switch. By using this type of "architecture" you can be connected to anyone, anywhere, anytime and conduct any type of communication at an affordable price. That's the catch, you see. Networks exist now which could allow you to actually conduct this type of communication. The problem is that current technologies are outrageously expensive.
ATM was developed as a unified approach to meeting all types of communication needs for now and into the future. It is a standard architecture developed by telecommunications carriers (largely made up of phone companies). This architecture is able to handle all types of transmission by chopping information (voice, images, text, etc.) into "packets" of data. By doing this, ATM can dynamically assign information as needed to these packets, and then address these packets to a destination, much like postal delivery. ATM has all types of data intermixed and transmitted together, routed based on an address code, and then reassembled at the appropriate destination.
Recognizing that standards were emerging to address all types of communications, the data communications industry seized the opportunity to begin utilizing the new standard to achieve better performance in data networks. Current builders of LANs (Local Area Networks), MANs (Metropolitan Area Networks), and WANs (Wide Area Networks) have constantly fought the need for transmission of greater volumes of data. ATM has been used to meet this higher bandwidth need. ATM is now often used in place of Ethernets or Token ring LANs. For a comparison, the older types of LAN technologies transmit at speeds around 10-16 million bits per second (know as megabits), and are actually more similar to Cable TV networks (broadcast in nature) than to switched networks. With ATM, these local networks are capable of speeds in excess of 50 megabits per second.
One of the most aggressive uses of ATM to date has been BellSouth's VistaNet trial in North Carolina. In conjunction with the State Government of North Carolina, BellSouth built a high speed data network using ATM standards and switches to connect a number of state educational institutions. With this network, North Carolina has conducted distance learning, teleconferences, and distance medicine.
While the next set of ATM applications are likely to be large commercial applications, telecommunications carriers are now seeking to use ATM in a more consumer-oriented market. ATM will possibly be used as a way of connecting you to the Internet or other networks, and allow you to receive these futuristic applications. By the end of the century, you may finally be able to place a video phone call to your mom, or even download your favorite movie for viewing at your convenience.
As the knowledge economy emerges, ATM will be a significant piece of the infrastructure to fuel it. But more importantly, ATM is making a big impact now. Understanding the capabilities and growth of this technology will be essential to making good information technology decisions in the near future.