# Understanding Network Speeds

When network optimization is discussed, you often hear terms relating to the speed of the network, in bits per second. For example, 10Mbps, which is the entry-level Ethernet network speed, refers to the network being capable of transferring information at the rate of 10 megabits per second, or 10 million bits per second. So what does this really mean to you?

Let's consider something that you might typically work with on a daily basis, such as a document written in Microsoft Word. A single-page Word document is about 20KB to 25KB in size. (A kilobyte roughly translates to 1,000 bytes.) We have a measurement mismatch here: We speak of network speeds in terms of megabits, but files are referred to in terms of kilobytes and sometimes megabytes. The basic difference here is that we are speaking of bits in one case and bytes in the other.

#### Bits and Bytes

Let's make sure we are clear about what each of these relatively obscure termsbits and bytesrefers to:

• A bit is a single binary representation of information in electronic terms. A bit has one of two possible states: either a one (1) or a zero (0). The bit is either on (1) or off (0), sort of like a light switch.

• A byte, on the other hand, is a collection of 8 bits and can have one of 256 possible values.

Let's revisit that Word document again. That file, expressed in bits, is 20 bytes x 8 bits per byte = 160 bits. Simple math shows that this file takes but a fraction of a second to be transferred across a 10Mbps connection.

Let's look at another example. A digital photograph takes about 500 kilobytes of storage, depending on the resolution; the higher the quality of the picture, the more storage space required. This file represents 4000Kb, or 4Mb, of data. This file will take just under half of a second to transfer across a 10Mbps connection. This should give you a good idea of how to relate the terms you see thrown about when talking about network speeds. As long as all the computers on your network share the same connection speed, you have a reliable standard by which to judge connectivity.

Your connection to the Internet will typically be quite a bit slower than your local home network speed. DSL, cable, and satellite Internet connections run at speeds up to 1.5Mbps. For Web surfing, email, and file downloads, this speed is fine for most networks. As a matter of fact, you can stream audio and video with this type of Internet connection. You get the idea by now: Things really don't take that long to move across the network.

## Other Types of Networking

While Ethernet is king in terms of networking these days, it was not always so. Much the same as the battle between the Sony Beta and the JVC VHS video recorder formats. In years past Ethernet was considered inferior to a technology introduced by IBM called Token Ring. Before Token Ring, there was ARCNET which was developed by Datapoint Corporation. The feature that endeared the Token Ring and ARCNET to the geeks of the time was their deterministic nature. There was a very orderly process and each computer on the network was guaranteed a time when it could transmit. Until a computer had the floor (so to speak) all it could do was listen. This guaranteed that there would be no traffic jams since only one computer could transmit at a time. Ethernet by contrast is what is called a multiple access medium and is prone to communications collisions. It is this nature that requires Ethernet to create a way to detect when multiple computers have attempted a transmission, detect the condition, and recover from it.

Next, let's turn our attention to the details of the various network types you'll typically use in a home environment.

ISBN: 0672328321
EAN: 2147483647
Year: 2003
Pages: 82
Authors: Eli Lazich