Networks and topologies: Factors that affect the performance of networks

The idea

Network performance is how quickly and reliably data moves between devices. Bandwidth is the maximum data transfer rate of a connection, so a higher bandwidth allows more data per second. The number of users or devices sharing the network affects performance because bandwidth is divided between them; more simultaneous users means each gets less. Wired connections such as Ethernet are generally faster and more stable than wireless connections such as Wi-Fi, which can suffer from interference, distance from the access point and physical obstacles. The type and quality of transmission media, network topology, hardware quality and signal interference all matter. A home network with one user streaming video may perform well, but the same connection with several users gaming and downloading at once can slow down noticeably.

What earns the marks

• Explains that greater bandwidth allows more data to be transferred per second, improving performance.
• Explains that more users or devices sharing the network reduces the bandwidth available to each device.
• Describes how wired connections such as Ethernet are typically faster and less prone to interference than wireless connections such as Wi-Fi.
• Identifies interference, distance from the wireless access point and physical obstacles as factors that can reduce wireless performance.
• Refers to the quality or type of transmission media, such as copper cable versus fibre optic, as affecting speed and reliability.
• Mentions that the network topology or the quality of hardware such as switches and routers can influence performance.

Common mistakes and how to put them right

• Confusing bandwidth with speed of light or latency.

  Put it right: Bandwidth is the maximum data transfer rate, while latency is the delay before data transfer begins.

• Saying more users always make a network faster.

  Put it right: More simultaneous users share the same bandwidth, so each user typically receives less.

• Assuming wireless is always better because there are no cables.

  Put it right: Wired connections usually offer higher speed, lower interference and more consistent performance.

Exam tips

• Link each factor to its effect, for example 'more users means less bandwidth per user, so downloads take longer'.
• Use comparative language such as 'higher', 'lower', 'more' and 'less' to show the direction of the effect.
• Apply factors to a scenario in the question, such as a school with many students using Wi-Fi at once, rather than listing them generically.