Prepared by: Les Spielman, Hospitality Automation Consultants

Broadband Report II - Transfer Speed Realities

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Bits and bytes. That's where this starts. Bit is short for BInary Digit, and it's the smallest unit of binary measure, usually either a 0 or a 1. A byte consists of eight bits (in mainstream computing). Two of many common areas where the terms bits and bytes are applied are data storage and network data-transfer rates. It's that second one I'm explaining here, and the definitions that follow don't in every case apply to the data storage definitions of the same terms.

Data-transfer rate is the speed at which data transmits from one device to another. Among the best known data-transfer rates is the one for conventional analog modems, whose top speed is currently "56K." Actually, its fastest download data-transfer rate is governed at 53.3-kbps. 53.3-kbps literally means 53,300

bits per second. There are 1,000 bits in a kilobit. Measuring bits per second is the traditional way to convey network data-transfer rates. Although technically speaking, the term kilobit should have a lowercase initial letter, most published reports capitalize it in abbreviation, resulting in "56-Kbps," or even

the really confusing "56K."

The newer versions of Internet Explorer or Netscape Navigator display download data-transfer rates in their status bars. This is easier to see when downloading a large file with the browser. Unfortunately, Microsoft and Netscape have both adopted the non-standard Kilobyte per second measurement (KB/sec). A Kilobyte is 1,024 bytes, and it is more properly used to measure data storage, not network data-transfer rates. Since a Kilobyte is eight times the size of a bit, data transfer rate measurements are a lot smaller when you convert them from bits per second to bytes per second.

The easiest way to get this is to compare the unknown with the known. Because I couldn't find a Kbps to KB/sec conversion table on the Internet anywhere, I sat down and did the math myself. Here's what I came up with: 28.8-kbps is equal to about 3.5 KB/sec. 53.3-kbps is roughly 6.5 KB/sec. 115-kbps is about 14

KB/sec. 256-kbps is roughly 31 KB/sec. 384-kbps corresponds to nearly 47 KB/sec. 400-kbps is nearly 49 KB/sec. 768-kbps equates to almost 94 KB/sec. The next step up from that is one million megabits per second (Mbps), which equals 122 KB/sec. And, finally, the networking speed usually referred to as T-1 is

1.544-Mbps, and that's about 188 KB/sec. (Note: I have rounded some of these numbers slightly for simplicity.)

The CableModemInfo Web site's Cable Modem FAQ says that most cable modem providers offer service over 300-kbps (36.6 KB/sec), or close to 600-kbps (73.2 KB/sec).

If you're a cable modem user, or a prospective one, you probably know that most cable-modem companies never advertise a specific data-transfer rate. They don't even give you a range. Instead they talk about how many times faster than analog modems their service is. There are a lot of reasons why they do that. An

unfortunate result is that it's hard to know what speed to expect. Several years ago, MediaOne's service technicians told me unofficially that something under 110 KB/sec, or about 900-kbps, was where they maxed out. And that's in an ideal setting (downloading a large file from MediaOne servers). With that frame of reference, the numbers line up, because 110 KB/sec is close to 1-Mbps.

Cable modem service has a serious disadvantage over DSL because its bandwidth isn't just shared at

the server, but all the way along the way from the server to your house. With DSL (and most other types of Internet access), you at least have the local pipe to yourself. The upshot is that cable services are far less consistent than DSL.