30 December 2016

What is Network Topology? & Its type

Network Topology

Topology is the physical layout or geometric arrangement of the components of a network.

A network topology is also the physical layout of computers, cables, and other components on a network. There are a number of different network topologies, and a network may be built using multiple topologies. The different types of network layouts are Bus topology, Star topology, Mesh topology, Ring topology, Hybrid topology and Wireless topology. This lesson explains what is bus topology.

There are different types of topologies:

Bus Topology

The bus topology uses a single cable in a linear fashion to connect systems together. Both ends of the cable must be terminated using what we call a terminator. When the cable gets faulty or un-terminated, the network collapses.

A bus topology consists of a main run of cable with a terminator at each end. All nodes like workstations, printers, laptops, servers etc., are connected to the linear cable. The terminator is used to absorb the signal when the signal reaches the end, preventing signal bounce. When using bus topology, when a computer sends out a signal, the signal travels the cable length in both directions from the sending computer.

When the signal reaches the end of the cable length, it bounces back and returns in the direction it came from. This is known as signal bounce. Signal bounce will create problem in the network, because if another signal is sent on the cable length at the same time, the two signals will collide.

Advantages of Bus Topology:

  • Easy to connect a computer or peripheral to a linear bus.
  • Requires less cable length than a star topology.

Disadvantages of Bus Topology:

  • Entire network shuts down if there is a break in the main cable.
  • Terminators are required at both ends of the backbone cable.
  • Difficult to identify the problem if the entire network shuts down.
  • Not meant to be used as a stand-alone solution.

Star Topology

In a star topology, all the systems are connected to a centralized medium i.e. a hub or a switch. If the centralized medium breaks down, the whole network breaks down too but if a system in the network breaks down, it doesn't affect the network. All the information passes through hubs and switches before it can be transferred to the destination. This arrangements reduce he risk of the entire network.

All systems are connected together whit a single cable but in an enclosed form having a ring-like shape.

Advantages of Star topology

  • Highly dependable.
  • Easy diagnosis of problem.
  • Expansion of the network is easy.
  • Network monitoring and management is centralized

Disadvantages of Star topology

  • Expensive.
  • Highly dependable on hubs and switches or others.

Mesh Topology

In a mesh topology all the computers are connected together using different cables. In Mesh topology, every network device is connected to other network devices. Mesh topology is costly because of the extra cables needed and it is very complex and difficult to manage.

The main advantage of mesh topology is multiple paths to the destination computer. If one link is down, we have another path to reach the destination.

Mesh Topology is not commonly used these days.

Ring Topology

In a ring topology, all computers are connected via a cable that loops in a ring or circle. A ring topology is a circle that has no start and no end and terminators are not necessary in a ring topology. Signals travel in one direction on a ring while they pass from one computer to the next, with each computer regenerating the signal so that it may travel the distance required.

The main advantage of Ring topology is that the signal degeneration is low since each workstation participating in the network is responsible for regenerating the weak signal. The disadvantage of ring topology is, if one workstation fails, the entire network will fail.

In this topology, all nodes are connected to one – another in the shapes of a closed loop or ring. Each device is connected directly to two or more devices, one on either side of it. Data travels in a one direction only. Each system can pass data to its adjacent system.

Advantages of Ring topology

  • Economical (short length cable needed o set up)
  • Suitable for optical fibre cable.
  • Performance of network is good during peak hours.

Disadvantages of Ring topology

  • Difficult to install.
  • Fault diagnosis - if one node fails entire network can fail.
  • Less reliable.

Hybrid Topology

Is the combination of any of the aforementioned topologies. Hybrid topology is a mixture of different topologies. Example is star-bus topology.

Thanks for reading...

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