Introduction to Computer Network Speed

Understanding the factors that determine performance of a computer network

Fibre optic broadband
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Together with basic functionality and reliability, the performance of a computer network determines its overall usefulness. Network speed involves a combination of interrelated factors.

What Is Network Speed?

Users obviously want their networks to run fast in all situations. In some cases, a network delay may last only a few milliseconds and have a negligible impact on what the user is doing. In other cases, network delays can cause severe slowdowns for a user.

Typical scenarios that are especially sensitive to network speed issues include

  • time to establish a new connection
  • time to load a Web page
  • time to download an app, operating system patch, or other files
  • ability to stream video content for long periods without glitches

The Role of Bandwidth in Network Performance

Bandwidth is a key factor in determining the speed of a computer network. Virtually everyone knows the bandwidth ratings of their network routers and their Internet service, numbers prominently featured in product advertisements

Bandwidth in computer networking refers to the data rate supported by a network connection or interface. It represents the overall capacity of the connection. The greater the capacity, the more likely that better performance will result. 

Bandwidth refers to both theoretical ratings and actual throughput, and it is important to distinguish between the two. For example, a standard 802.11g Wi-Fi connection offers 54 Mbps of rated bandwidth but in practice achieves only 50% or less of this number in actual throughput.

Traditional Ethernet networks that theoretically support 100 Mbps or 1000 Mbps of maximum bandwidth, but this maximum amount cannot reasonably be achieved either. Cellular (mobile) networks generally do not claim any one specific bandwidth rating but the same principle applies. Communications overheads in the computer hardware, network protocols, and operating systems drive the difference between theoretical bandwidth and actual throughput.

Measuring Network Bandwidth

Bandwidth is the amount of data that passes through a network connection over time as measured in bits per second (bps).Numerous tools exist for administrators to measure the bandwidth of network connections. On LANs (local area networks), these tools include netperf and ttcp. On the Internet, numerous bandwidth and speed test programs exist, most available for free online use.

Even with these tools at your disposal, bandwidth utilization is difficult to measure precisely as it varies over time depending on the configuration of hardware plus characteristics of software applications including how they are being used.

About Broadband Speeds

The term high bandwidth is sometimes used to distinguish faster broadband Internet connections from traditional dial-up or cellular network speeds. Definitions of "high" versus "low" bandwidth vary and have been revised over the years as network technology improved. In 2015, the U.S. Federal Communications Commission (FCC) updated their definition of broadband to be those connections rated at least 25 Mbps for downloads and at least 3 Mbps for uploads. These numbers reflected a sharp increase from the FCC's previous minimums of 4 Mbps up and 1 Mbps down.

(Many years ago, the FCC set their minimum at 0.3 Mbps).

Other Factors in Computer Network Performance

Bandwidth is not the only factor that contributes to the perceived speed of a network. A lesser known element of network performance - latency - also plays an important role.

Next page > What About Network Latency? > Page 1, 2

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