# Performance of a Network

The performance of a network is an important issue in every network. To determine the performance of a network there are various parameters such as how efficient a network is, is the network reliable, the speed of data transmission, is the network secure, etc.

Here we will discuss the terms which are used to decide the performance of the network – how good the network is?  Let us discuss how we determine the quality of service a network provides and its overall measurement. ## Performance of a Network

### Bandwidth

Bandwidth in networking can be defined as the maximum number of bits that can be transmitted through a link in a network in a unit of time. However, the term bandwidth can be computed in two different contexts i.e., in Hertz and in bits per second

Bandwidth in Hertz:

Bandwidth in hertz can be defined as the range of frequencies a composite signal carries or it can also be defined as the range of frequencies a channel can transmit.

Bandwidth in Bits Per Seconds:

Bandwidth in bits per second can be defined as the maximum number of bits a link in a network can transmit per second.

However, there is an explicit relation between both bandwidths in hertz and in bits per second. If a bandwidth in hertz increases there is a direct increase in the number of bits a channel can transmit per second. That means bandwidth in hertz is directly proportional to bandwidth in bits per second.

This relationship also depends on which kind of transmission is used baseband transmission or if the transmission with modulation is used.

### Throughput

Throughput can be defined as the speed at which data can be transmitted on a link in a network. Though bandwidth and throughput may sound similar as bandwidth also specify the number of bits a link can transmit per second they are genuinely different.

If T is the throughput of the link in a network and B is the bandwidth of the same link in a network. The value of T will always be smaller than the value of B. This means that bandwidth specifies the potential capability of the link i.e., how fast the link can transmit data and the throughput specifies the actual capability of the link i.e., how fast the link transfers the data.

### Latency

Latency can be defined as the time a data takes to get delivered at the destination from the time the first bit of the data was sent out from the source. However, we can classify this time using four components as you can see in the formula below:

Latency = propagation time +transmission time +queuing time + processing delay

Let us understand each of these components.

1. Propagation Time: Propagation time is a time a bit takes to reach the destination over a link.

Propagation time = Distance/ Propagation speed

2. Transmission Time: We do not send a bit; we transmit an entire message. So, the transmission time is the time taken by the entire message to arrive at its destination. This is a time between the first bit of the message leaves the source and the last bit of the message arrive at the destination.

Transmission time = Message size/ Bandwidth

3. Queuing Time: Queuing time is the time a message is held at the intermediate node or the destination before the message is processed.

4. Processing Delay: Processing delay is the time taken by the intermediate node or the destination to process the message.

This is how the performance of a network is determined with the help of various parameters. The performance of a network specifies the quality of service it is providing to the end-users.

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