Bus topology is a type of network topology  in which all the nodes are connected to a single cable called backbone cable. Bus topology is also known as Line topology. There will be comprehensive discussion on this topic “What is Bus Topology?”.  Bus Topology is very simple Type of Network Topology that you can use in your Computer Network. Well, I am writing this article in order to explain each and every aspect of Bus Topology along-with real life examples, advantages and disadvantages.

Introductory video about Bus Topology

What is Network Topology?

Well, for those who are unaware of the term Network Topology, let me explain this term for you to get proper understanding. The term Network Topology refers to the organization and layout of a Computer Network.  It defines that how different components of a Computer Network connect to each other. Topology of a Network assist you in understanding location or positioning various Network Devices. Apart from this, a Network Topology also gives you the details on the path for data flow within a Network. When it comes to error handling and troubleshooting of Computer Network, you always get help from Network Topology. Network Topology has following two types:

1. Logical Topology
2. Physical Topology

Logical Topology

The Logical Topology, as the name indicates, is logical or conceptual in nature. In reality, Logical Network Topology is a graph. The nodes of this graph are Network Devices while the edges are simply the links between these devices. In short, Logical Topology gives us details about the placement of Network Nodes and Communication Links. The main focus of this type of topology is to explain the communication between Network Devices and signal flow. That`s why it is also known as Signal Topology.

Physical Topology

A Physical Topology defines the physical arrangement of Servers, Clients, Communication Devices and even Network Media. This topology explains the geographical location of Network Devices and physical connection between the devices. You can consider this as to be same as the arrangement of furniture in your drawing room or architecture of your home.

To read more about the term Network Topology, you can refer to my article: What is Network Topology?

What is Bus Network Topology?

Bus Topology or Bus Network is one of simplest Type of Network Topology. Bus Topology consists of a single central cable. This cable is referred to Backbone Cable in Bus Topology. All the Computer Network Nodes like Server, Client and Network Device are attached to the Backbone Cable with the help of drop links. The Backbone Cable is of chief importance in this topology. So, any form of damage to it can stop the communication in whole Computer Network.

Bus Topology Examples and Applications

The simplest example of this topology is connection of landline telephone. Suppose you have a two story house and you want landline connection on every floor. Now answer one question. Will you apply for two landline connections? The answer is simply no. Because if you apply for two separate connections, it will become costly for you. In fact, you will only apply for a single landline connection. After connection, you will run a main landline cable from the pole to the ground floor and from the ground floor to the first floor. You will puncture the wire on both floors and attach the telephone socket to it. In this way, the cable will be shared among two telephones but you will get facility on both of your floors. Further, the extension to other floors also becomes easy and less expansive.

Bus Topology Concepts and Features

Basic concepts are the foundations of every thing. But if you talk about technology, basic concepts are vitally important. So, in this section, I am going to explain the basic concepts of this topology. These concepts will help you in understanding the working of this topology.

Backbone Cable

Obviously, as I mentioned earlier that Backbone Cable is the main component behind the working of Bus Topology. This is a main cable that serves as the backbone of the Network. The name Backbone is given to to it due to similarity with human backbone. The Backbone Cable serves the purpose of transmitting signals across a Network as human backbone is responsible for the communication of neurotransmitters. This is usually a heavy duty cable for supporting reliable communication. However, the Backbone Cable requires great deal of care and you have to look after it to save it from damage. Any kind of damage to it can put whole Computer Network at stake. Whenever, the there is some form of damage to the cable, communication through it stops. You may have some questions in your mind. Let me answer these common questions:

Terminator

You cannot leave the end points of a Bus Network open. This is because of the fact that it will cause signal reflection. A signal reflecting from the end point may interrupt with the signal coming from the opposite end. In order to deal such a situation, you need to put a Terminator at each end of the Backbone Cable. The Terminator simply absorbs the signals and prevents the back reflection. So the major motive behind the use of Terminator is to make the Network error free and reliable.

You can also check another definition of Terminator

Drop Link

Another important concept in Bus Topology is Drop Link. Drop Link is like a patch cable that creates a path for signals to travel. A Network Node attaches to the Backbone Cable through the Drop Link. One end of the Drop Link connects to the Backbone while other end attaches to a connector. This connector is plugged into Network Interface Card (NIC) of any Network Device. If you want to add a new Node in your Computer Network, you simply need to puncture Backbone Cable and attach a Drop Link to it. So, it actually makes the Network flexible. Similarly, if you want to exclude an existing Node, you simply need to detach the Drop Link.

Node

Any Client, Server or any other Network Device that is a part of Computer Network is basically a Node. A Node can play multiple roles and the decision of the role depends upon the activity and responsibility. Following are the common roles of a Node:

• Client
• Server
• Intermediate Node

In most of the cases, Client or Server are computing devices. However, an intermediate node can be either a computing device or non-computing device. You might be thinking about non-computing devices. Following are some examples of non-computing devices:

• Printer
• Network Repeater
• Hub
• Switch

Bus Topology Diagram and Working (Easy Explanation)

If you talk about Working of Bus Topology then mark my words that is really straight-forward. I will be explaining the working in easy way with the help of Bus Topology Diagram. First of all, I will explain the structure of Bus Topology. It will be mighty helpful for you to understand the working. Physical organization of Bus Topology contains Backbone Cable, Terminator, Drop Links and obviously Nodes. You already know that Backbone Cable is the main communication channel of the Computer Network. There is a Terminator present at each end of the Backbone Cable for stopping the signal from reflecting back to the cable. This reflection may cause problems in communication. Each Node has a connection to the Backbone Cable with the help of Drop Links. You can clearly, see this scenario in the diagram.

So, I hope that up to now you have understood the Physical Topology of Bus Network. In a typical Bus Topology, only one computer can communicate or send data to another at a single time. Moreover each Node in the Bus Network can either transmit data or listen to the line. Data message contains the address of the destination. Further, the communication from the Sender is Broadcast. During the Broadcast Communication, each Node on the Network will be able to receive data. However, on receiving the data, each Node checks the destination address of the data. If the receiving computer address is not same as the destination address of the data, the receiving Node simply discards the data. On the other hand, if the Node address and destination address match with each other, the Node keeps the data.

How Bus Topology Works? – Example

Suppose a Node A wants to send to another Node D, and there are Nodes B and C in between these two. Here Node A will be Sender and Node D will be the receiver. The data message from A will contain D as destination address. Due to the Broadcast Communication, the Nodes B, C and D will receive the data message.Now, when Nodes B and C receive the data message, these will check the destination address. Clearly, the destination address will not be same at both locations B and C. So, both of these will discard the data message. But on the Node D, the situation will be entirely different. The Node D will not discard the data message as the destination address and Node address are same. So, the Node D will keep the data message because it is the intended receiver.

A Node in Bus Topology is not responsible for forwarding data to other Nodes. Instead, Sender Node only Broadcasts the data. So, the Network keeps on working even if one or more Nodes are out of order. So, in this way, Bus Topology is very much reliable due to this fact.

Bus Topology Advantages and Disadvantages

So, I hope that structure and working of Bus Topology are quite clear to you now. Each technological thing has associated advantages and disadvantages. So, it is good to be aware of these before implementing any technology. For the sake of knowledge, I am going to elaborate various Advantages and Disadvantages of Bus Topology in the coming section.

Pros and Cons

Pros

Advantages of Bus Topology

• Makes it easy to establish and manage a small sized Computer Network
• This topology is flexible enough to add/remove Nodes
• It is less expensive form of Network Topology that requires least amount of cabling and Network Devices
• In this Type of Topology, problem in one or more Nodes doesn`t effect the working of whole Network

Cons

Disadvantages of Bus Topology

• Backbone Cable is the critical component of this topology. So, any kind of problem in it can affect the whole Computer Network
• You should take great care of the Terminator at each end because any problem in the terminator can cause signal reflection
• Fault detection and troubleshooting process of individual Network Devices is really difficult as compared to other Types of Network Typologies
• You cannot use this Network Topology Type for large scale Networks
• Adding too many Nodes on the main cable can also cause degradation of communication and decrease the Network performance

FAQs

1.Where is Bus Topology used?

You can use it anywhere you want. You can find out millions of Examples of Bus Topology in everyday life. The electricity wiring, gas piping and water piping are simple examples of non-Network systems.

2.When would you use a Bus Topology?

Bus Topology is basically an inexpensive Network Type. So, whenever you need to establish and use a cheap Network, this topology is probably the best choice for you. Extending your landline connection throughout your house requires you to share a single landline cable across multiple telephone sets in different rooms.

3.Which cable is used in Bus Topology?

There is no single cable for this purpose. Instead you can use any type of Network Cable. Whether you use a Twisted Pair Cable or Coaxial Cable there is absolutely nothing wrong about it. You can even use Fiber Optic Cable for high speed and high performance Computer Network.

4.Is Bus Topology expensive?

Absolutely not. It is really inexpensive to establish. You don`t require any special or costly equipment for using it.

5.Which connector is used in Bus Topology?

This strictly depends upon the type of cable you are using. If you are using Twisted Pair Cable then RJ45 connector is most suitable.

6.What is a popular Ethernet Cable used in Bus Topology?

Twisted Pair Cable is most popular and commonly used in this topology. Previously, Coaxial Cable was commonly used in terms of Backbone. If you want to use Twisted Pair Cable then Shielded Twisted Pair (STP) is far better choice as compared to Un-shielded Twisted Pair (UTP).

7.Why are Bus Networks slow?

Bus Networks become slow if you add too many devices in it. When you add too many devices the traffic through the Backbone Bus Cable increases. With increase in traffic, the chances of signal interference and collision also increase. Further, too many drop links also cause slowness.

8.What are the Features of Bus Topology?

• It is really quick to establish and manage
• Bus Topology is cheapest when compared to other Types of Network Typologies

9.What is the Advantage and Disadvantage of Bus Topology?

The main advantage is that in case when a Node is experiencing any problem the whole Network communication is still going on. The biggest disadvantage is the Backbone Cable itself. Another disadvantage is that it is only suitable for small sized Networks.

10.Why is it called Bus topology?

The answer is really simple. If a bus (vehicle) is traveling from one city to another it passes through all the cities in between. Same is the concept of working of Bus Topology. That`s why it is known by the term Bus.

11.What are Terminators in Bus Topology?

In Bus Topology, you cannot leave the Backbone Cable ends open. This will cause signals to reflect from the end back into wire. This reflection can cause collisions and other problems in communications. So, a Terminator is placed at each end of the Backbone Cable to absorb signals and prevent them from reflecting back.

12.How does Bus Topology transmit data?

Sender encloses the destination address in the data and Broadcasts it in the Network. Each device between Sender and Receiver receives the data and checks the destination address. The Node that has the same address as that of written in the data by Sender is the proper receiver.

13.Why Bus Topology is passive?

Nodes in Bus Topology are responsible for only two operations: 1) Send 2) Listen to receive. Apart from this, the Nodes have no responsibility. A Node can`t even amplify the communication signal. Similarly, communication signal in this topology is broadcasted by the Sender. So, any intermediate doesn`t have to re-transmit the received signal as with the Ring Topology. That`s why Bus Network is passive in nature.

Final Words

Each Computer Network requires a certain Network Topology. If you are looking to establish a home network or small office network and you have a little budget then Bus Topology is probably the best option available for you. It will work absolutely fine unless you try to overload it by over extension. By employing this Type of Network Topology, you get a reliable Network that is not affected by any problem in one or more Network Devices. I hope that you might have got proper understanding of this Network Topology in each and every respect. Please do provide me with your valuable feedback. It really matters a lot to me. I have much more for you people. So stay tuned.