Network performance refers to how well data is transmitted throughout the network.
Some of the factors which affect network performance are:
- The bandwidth of the network and number of users on the network
- The error rate
- Latency
- The transmission media used (Wired or Cable Type) / Wireless(Connection type)
Bandwidth and Active Users
- Bandwidth describes how much data can be transferred over the network in a given time.
- Bandwidth is NOT about the speed that data is transmitted.
- Networks can support many users
- The bandwidth has to be shared amongst the users. However, bandwidth isn’t always shared equally.
- The ‘contention ratio’ is used to measure the ratio of users compared to the available bandwidth.
Imagine the available bandwidth as a litre(1000ml) of water in a jug. If one person on the network is streaming videos, they might use 400ml of the water (data). That only leaves 600ml of water (data) to share amongst all of the other users on the network.
Network Speeds – Bit Rate
- The speed of a network is measured in ‘bits per second’.
- This is also known as the ‘bit rate’
- One bit of data is a single 0 or 1
The measurements used in relation to network speed 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
Latency
- Latency describes how much time it takes for a packet of data to travel across the network.
- On a small LAN, latency is not really a problem as all of the nodes are near to one another.
- But on larger networks, e.g. WANs, latency can become more of an issue.
- Every cable, switch and router on the network adds a delay (latency), to the connection
- Networks with long delays are called high latency networks.
Error Rate
The number of errors that occur during data transmission is another factor which can affect network performance.This is called the ‘error rate
An error can happen when, for example, a binary 1 is sent across the network, but instead, a binary 0 is received.
There are two reasons why this can happen:
Interference – If a cable, or switch, is placed in close proximity to electrical equipment e.g. motors, then interference from the equipment may cause the bits to flip randomly. Shielded cables can be used to reduce the problem.
Weak signal – As the cable length gets longer, the signal can become too weak and errors can begin to creep in.