Network Performance

In this tutorial, you will learn about network performance. You will also learn about the performance parameters affecting the network, and we will discuss how the parameters are useful for improving the network.

Contents:

1. What is Network Performance?
2. Network Performance Parameters/a>
3. Bandwidth Units
4. Calculation of Bandwidth
5. Throughput Measurement
6. Delay or Latency Measurement
7. How does Delay Occur on a Network?
8. Jitter Performance

What is Network Performance?

The performance of a network plays a major role in the communication between devices. The amount of time in which data is transmitted from sender to receiver, the speed at which data travels along the communication path, and the delay between communication devices over the network, is known as performance. In simple words, performance means how good is your network.

• After the network is created, the network administrator should regularly check the network performance to improve the network performance.
• By using network performance parameters, one can get an idea about the actual performance of the network.

Network Performance Parameters

So, we understood the definition of network performance. But how can we measure the performance of the network? For that, we have 4 types of network performance parameters as follows:

1. Bandwidth
2. Throughput
3. Delay or Latency
4. Jitter

• Bandwidth: It is the maximum capacity of data that can travel over a network between communication devices at a specific time.
• Throughput: The amount of actual data that travels from sender to receiver in a particular time is known as throughput.
• Delay or Latency: The time taken for the entire message to reach the receiver from the sender is called delay.
• Jitter: It is a kind of delay that describes the time variation in the data received by the receiver. For example, suppose the sender has sent 4 packets to the receiver. The first packet arrives at 30 ms, the second at 40 ms, the third at 35 ms, and the fourth at 37 ms. Hence this change of time is known as Jitter.

Bandwidth Units

Bandwidth is one of the most important parameters of network performance, which tells you about the maximum capacity of data that can travel over the network between communication devices at a specific time. If there is more bandwidth between the sender and receiver then more data can be sent or received by the sender and receiver.

We can measure bandwidth in terms of Hertz (Hz) and bits per second (bps). Typically, hertz (Hz) is used in analog signals, and bits per second unit (bps) is used in digital signals. Let us understand these two units of bandwidth.

• Analog signal bandwidth: Analog signals are continuous in nature and have continuous values. In analog signals, network bandwidth can be measured by finding the difference between the signal’s highest frequency and the lowest frequency, expressed as Hertz (Hz).
• Analog signal bandwidth = Highest frequency signal – Lowest frequency signal
• Digital signal bandwidth: Digital signals are discrete in nature and contain discrete values. In digital signals, bandwidth can be measured by finding out how many bits travel in one second on a communication channel, expressed as bits per second.
• Digital signal bandwidth = Bits transmitted over a communication channel in a second.

Calculation of Bandwidth

We now know that bandwidth is expressed in terms of hertz (Hz) and bits per second (bps). Let us see how bandwidth is calculated on an analog signal and digital signal.

The diagram below describes how bandwidth is measured in an analog signal and a digital signal.

• As shown in the above figure, the highest frequency signal and lowest frequency signal in an analog signal are 10000 Hz and 3000 Hz respectively. So the analog signal bandwidth is,
  Analog signal Bandwidth = Highest frequency signal – Lowest frequency signal
  Analog signal Bandwidth = 10000 Hz – 3000 Hz
  Analog signal bandwidth = 7000 Hz
• Similarly, in digital signals, you can see that 12 bits are transmitted in a second on a communication channel. So the digital signal bandwidth is,
  Digital signal bandwidth = bits transmitted per second
  Digital signal bandwidth = 12 bits per second (bps)

Throughput Measurement

Throughput is the second most important parameter of network performance that tells you how much actual data travels over a communication channel in a specific amount of time.

• The throughput measurement tells you how fast data can actually be transmitted over a channel.
• The main difference between bandwidth and throughput here is that bandwidth is the potential measure that tells the capacity of data that can be transmitted, whereas throughput tells you how fast the data can actually be sent by the sender.
• Throughput can be calculated as,
• Throughput = (frames * average of bits) / seconds
• Suppose the bandwidth in the network is 5 Mbps, and the sender sends 2400 frames per minute and each frame has 20000 bits. So, the Throughput will be,
  Throughput = (2400 * 20000) / 60
  Throughput = 400 * 2000
  Throughput = 0.8 Mbps

The below diagram describes the Throughput measurement of data.

The left side of the above diagram shows that the receiver can receive 4 packets at a time, while on the other side you can see that the bandwidth of the network is high so that it is capable of receiving 10 packets at a time. This diagram also shows that if the bandwidth is high then the throughput will also be high.

Delay or Latency Measurement

Delay or latency is the total time taken by the entire data to reach the receiver from the sender. When a packet is sent by the sender to the receiver, it passes through several paths. In between communication, packet suffers from four types of delays, and the total of these four delays is known as latency or delay. The four types of Delay or Latency are as follow:

1. Propagation time
2. Transmission time
3. Ring Topology
4. Queuing time
5. Processing delay

• Propagation time: It is the time required for a bit to transmit from sender to receiver. It can be measured by,
• Propagation time = Total Distance / Speed of propagation
• Transmission time: The duration between the sender sending the first bit and the receiver receiving the last bit of the message is known as transmission time. Transmission time varies according to the size of the message and bandwidth. It can be measured by,
• Transmission time = Message length / Bandwidth of the channel
• Queuing time: When the message is sent from the end device to the intermediary device, the intermediary device holds the message for some time which is known as queuing time. The queuing time is not fixed, it varies according to the traffic on the channel.
• Processing delay: The time taken by the intermediary devices to examine the header of the packet and decide where to send the packet is known as processing delay.
• We have understood the four types of delay, so now we can calculate the total delay as,
• Total Delay = Propagation time + Transmission time + Queuing time + Process delay

How does Delay Occur on a Network?

As we have seen, there are 4 types of delay or latency. They are propagation delay, transmission delay, queuing delay, and processing delay. So let us understand how the delay occurs on the communication channel.

The diagram below shows how the delay is occurring on the communication channel.

• As you can see in the above diagram that PC-1 has sent a packet to Router-A. First, the router will examine the received packet, and the amount of time it takes to examine the packet is known as processing delay.
• After examining the packet, the router will hold the packet in a queue for some time which is known as queuing delay, then it will wait for the transmission link for some amount of time which is known as transmission delay.
• Finally, the packet will transmit to Router-B and the time taken by the packet to be transmitted from Router-A to Router-B is known as propagation delay. This whole process will be repeated on Router-B.

Jitter Performance

Jitter is a kind of delay that describes the variation of time in the data received at the receiver. Jitter can occur due to heavy traffic on a network or a broken link.

The figure below shows that there is a jitter problem on the communication channel.

The above diagram shows that the sender has sent 4 packets to the router. It also shows that the first packet arrives at 40 ms, the second packet at 30 ms, the third packet at 35 ms, and the fourth packet at 25 ms to the router. Here the variation of time is known as Jitter.

• If you are video calling with someone but suddenly the connection breaks or suppose you are talking to a person and suddenly the voice starts breaking. This problem is caused by jitter.
• A network administrator can control jitter problems on a network by checking the network’s connection, using the quality of services on the network, and regularly updating the network’s routers. A network administrator can also add a buffer to manage traffic.