# Network performance

## 2. Bandwidth

Any network has a limit in *how much* data can be moved across it in a given time. This quantity is called the **bandwidth** of the network.

Bandwidth is measured in **bits per second** also called the **bit rate**.

As you would expect, the higher the bandwidth the more expensive the network becomes to put together because of the cost of the cables and equipment.

Designing a network is a matter of balancing cost to the required performance.

Typical bit rates are:

- Kilobits per second (Kbps), a thousand bits per second.
- Megabits per second (Mbps), a million bits per second.
- Gigabits per second (Gbps), a thousand million bits per second.

The table below shows the bandwidth of various networks

You do not have to memorise all these numbers, it is just to show that networks come in a range of bandwidths:

Bandwidth | Decription |
---|---|

56Kbps | Bandwidth of a non-broadband dial-up modem |

2 to 10 Mbps | Basic copper wire based broadband (download bandwidth) |

10 to 75 Mbps | Fibre-Optic based broadband (download bandwidth) |

10 - 100 Mbps | Ethernet wired network using Cat-5 cable |

1 Gbps - 10 Gbps | Ethernet wired network using Cat-6 cable |

54 - 150 Mbps | Standard Wi-Fi connection |

900 Mbps | Fast Wi-Fi |

**Challenge** see if you can find out one extra fact on this topic that we haven't
already told you

Click on this link: Typical Ethernet speeds