More of this Feature • Part 2: Toast.net Evaluation

Join the Discussion "Does anyone have suggestions for some free or cheap software tools/utilities for testing throughput and bandwidth from the desktop to the server in a LAN?" -MAESTROG

Related Resources • Introduction to Bandwidth and Latency • Bandwidth/Speed Tweaks

This article discusses the concepts behind online speed measurement. Follow-up articles (see sidebar) critique the effectiveness of individual testing services based on actual trials.

Bandwidth and Speed

In computer networking, the term bandwidth refers to the rate of data transfer. Very often the bandwidth numbers one sees and hears represent theoretical or peak performance of a device. A 100 Mbps Ethernet adapter installed in a computer with a slow processor, for example, rarely exceeds 10 Mbps in actual performance. Traditional dial-up modems, advertised as capable of 56 Kbps, never actually perform at that rate in practice.

The term speed is often used synonymously with data rate in networking. Technically speaking, speed refers to the user-perceived performance of the network application. Speed correlates positively with bandwidth in many cases, but not always.

One's Web browser, for example, may perform "slowly" on a high-bandwidth network for several reasons, such as a bottleneck at the Web server or at one's ISP. Those who have upgraded from traditional dial-up to broadband may already be familiar with the phenomenon. It's common to attribute performance problems to a "slow network" even though the local area data transfer rates (when transfers occur) remain high.

The Need for Speed Tests

Network performance depends on many factors. To help a person understand the state of their network, modern operating systems support various performance monitoring mechanisms. Though useful, these features tend to drastically oversimplify or "dumb down" the analysis of network performance.

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