Network Basics: Speeds

The speed of computer networks is measured in terms of the amount of information units (bits) that can be transmitted per second. Often, to transmit one character of a text, eight bits are necessary. Thus, if a network would have a speed of 8 bits per second (bps), one character per second could be transmitted. The speed of real networks is much higher. Usually Kilo, Mega and Giga bits per second are common meassures (Kbps, Mbps, Gbps), which mean thousands, millions or billions of transmitted bits per second.

The different types of computer networks are working with different speeds. In general, networks with smaller geographic expansion run at a faster speed: WANs often slower than 1 Mbps, LANs at about 10 Mbps, and High-speed LANs up to 100 Mbps. New technologies like ATM promise speeds up to 2 Gbps for all kinds of networks. Remember that not all of this performance can be used to transmit the true data, because a considerable part of the data are headers with control information.

The following graph displaying the speed-requirements of different applications shows, why permanently higher speeds are necessary.

One can see, that common future applications like multimedia need a faster underlying network technology.