Chapter 13. The Oldest LAN Protocol Is Still Kicking: ARCnet

SOME OF THE MAIN TOPICS IN THIS CHAPTER ARE

Overview of ARCnet

Troubleshooting ARCnet

Of the networking technologies still widely in use today, ARCnet is the oldest. It was created at Datapoint Corporation in the 1970s and is a token-passing system similar in many ways to Token-Ring. For small networks, ARCnet is a reliable technology that is easy to configure. However, also like Token-Ring, ARCnet equipment is produced by only a small number of manufacturers when compared to the huge number of manufacturers making Ethernet equipment. Along with its slow network speed (usually 2.5Mbs to 10Mbps), this makes ARCnet a prime candidate for an upgrade to newer technology for networking desktop systems. Although it was originally developed for the purpose of connecting minicomputers to create a local area network, you would be hard-pressed to find it used that way today.

All that said, ARCnet is still widely used for other purposes. For example, you can find this technology embedded in various controllers used for industrial automation on factory floors. The basic ARCnet standard is defined as ANSI/ATA 878.1, but extensions and other changes to the original standard have been developed over the years . This chapter gives you a good overview of the details of ARCnet operations and the hardware components involved. However, many vendors offer variations on the original standard, allowing for greater distances between nodes, for example. For those interested, the ARCnet Trade Association (ATA) keeps a Web page that contains links to many manufacturers of ARCnet hardware. You can visit their Web site at www.arcnet.com. There is also an ARCnet user group in Europe, which you can reach using the URL www.arcnet.de/.

As a matter of fact, you've probably encountered ARCnet at some point in your life and just didn't know it. For example, when you order at McDonald's or White Castle Hamburgers, the cash register (oh, I mean point-of-sale terminal) is probably linked to other similar systems through ARCnet. When you turn up the thermostat at work, there's a good chance that it's connected to a central computer for the building that uses ARCnet. You'll even find ARCnet used to connect medical devices, such as X-ray machines, at your doctor's office!

So although ARCnet is the oldest networking technology around today, its stability, simplicity, and low overhead make it a perfect solution for many different kinds of applications. Sometimes newer isn't always better! After all, would you want someone who says "Do you want fries with that?" at your favorite drive-through to be in charge of configuring a TCP/IP network?