Bus Topology | Working of Bus Topology | Pros and Cons of Bus Topology

     Introduction of Topology

Physical or Logical layout of structure called topology, in which all nodes are connected. Network topology is the arrangement of the elements of a communication network. The physical topology of LAN refers to the way in which the stations are physically interconnected. Each topology has its own strengths and weakness.

Feature of network topology: 1. The topology should be flexible. You can increase or decrease number of nodes in topology. 2. The cost of physical media and installation should be minimum. 3. The network should not have any single point of complete failures.

Types of Topologies

There are 5 types of topologies in computer network:

Bus Topology

A bus topology is a network setup in which each computer and network device are connected to a single cable or backbone. Bus topology also called horizontal topology. In bus topology, multiple devices are connected one by one, by means of connectors or drop cables. When one computer sends a signal up (and down) the wire, all the computers on network receive the information, but only one accepts the information (using address matching). The rest discard the message.

Figure: Bus Topology Structure

The cable to which the nodes connect is called a "backbone". A host on a bus network is called a Station or workstation. Bus is passive topology, because it requires termination. Cable cannot be left un-terminated in a bus network. Terminators are required both ends of cable. Terminators were the 50-ohm resistor that were connected to each end of cable.

Figure: Bus Topology Animation

In a bus network, every station will receive all network traffic, and the traffic generated by each station has equal transmission priority. For example, station 1 wants communicate to station 2. But after sending data by station 1, all stations those are connected with bus will received data. In order for nodes to transmit on the same bus simultaneously, they use carrier sense multiple access (CSMA) protocol.

Advantages:

Easy to use and easy to install.

Needs fewer physical connectivity devices.

A repeater can also be used to extend a bus topology.

Low cost.

Disadvantages:

Heavy network traffic can slow a bus considerably.

It is difficult to troubleshoot a bus topology.

Failure of cable affects all devices on the network.

Difficult to add new node.

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