### Factors That Affect The Performance Of Networks

We talked about what a network is in the previous section, but it is also important to understand how the performance of network is affected.

### How do we calculate the speed of data in a network?

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### Bit Rate x Bandwidth

The bit rate is the speed of 1 bit multiplied by the volume of data that can be sent at once gives the total speed.

When we talk about the performance of a network, we mean how fast data is able to transfer from one device in the network to another. The time taken for the data to be requested and then sent is known as latency.

Often we refer to the delay in receiving data as lag.

There are a number of factors that could affect the speed of data transfer in the network:

## Bandwidth

Imagine the cables in the network are a little like a river. If there are two rivers where the water is flowing at the same speed, but one is wider, more data can flow down the second river even though the water is travelling at the same speed.

In the same way, the bandwidth is the volume of data that can travel along media at the same time.

## Bit Rate

Where bandwidth measures the volume of data that can travel at once, bit rate measures how fast the data can travel. This is calculated by measuring bits per second.

## Number of Users

Have you ever noticed that your internet slows down at the weekend, or when something exciting is happening on TV? The reason for this is likely to be something to do with how many people are using the network.

Devices inside a network will be sharing the available bandwidth. If there are 4 devices on a network, then they will receive 1/4 of the bandwidth each*. As more devices join the network, the bandwidth is divided in to smaller and smaller amounts for each device eventually making the network noticably slower.

*This is actually a little bit simplistic, as the router is intelligent enough to divide the bandwidth depending on what each device is doing.

## Type of Network Media

Media in this case refers to the type of cable or wireless connection. As a rule, wired connections tend to be faster, but less portable. Copper cable is faster than WiFi, however fibre optic cable is much faster than ethernet (a common type of copper cable).

## Type of Error Checking

To ensure that data is not corrupted, there are a number of methods that can be used to check that the data is correct. Error checking methods such as Echo back (where the receiver sends a copy of the data back) and majority voting (where the data is sent three times) cause additional data to be sent through the network and can cause congestion.

## Poor Hardware Planning

When a network is set up, bottlenecks can be created in the network by attempting to route too much network traffic through a single point. This can often be remedied by adding additional routers or switches.

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