Network Topologies

Before understanding network topologies, let’s first understand what is Network?

A network is a set of devices connected by communication links. The devices are also called nodes. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network.

Network Topology

The network topology refers to the way the network is laid out physically. It describes the method used to configure cables, computers, and other peripherals in network. Two or more devices connect to a link and two or more links form a topology. The topologies can be physical as well as logical, but we will talk about physical network topologies.

There are five basic network topologies:

  • Bus topology
  • Ring topology
  • Star topology
  • Tree topology
  • Mesh topology

Bus Topology

In Bus topology, a single long cable acts as a backbone to link all the devices in a network. A terminator is connected at each end. The single travels along the cable and it becomes weaker as it travels the path, so bus topology supports limited number of devices.



Advantages of Bus Topology

  • It is easy to install.
  • It uses less cabling than mesh or star topologies.

Disadvantages of Bus Topology

  • It is difficult to find the problem if some fault occurs in network.
  • The entire network shuts down if there is breakage in main cable.

Ring Topology

In Ring topology, each device/host is connected to two neighboring devices on either side of it. A signal is passed along the ring in one direction, from device to device, until it reaches its destination. Each device in the ring incorporates a repeater.



Advantages of Ring Topology

  • It is relatively easy to install and reconfigure.
  • Fault isolation is simplified.

Disadvantages of Ring Topology

  • A break in the ring (such as a disabled station) can disable the entire network.
  • As all the devices are wired together; to add new device to the network, the whole network should be shutdown.

Star topology

In star topology, each device is connected to a central controller called hub. The devices are not directly linked to one another. The hub acts as a central server: If one device wants to send data to another, it sends the data to the hub, which then relays the data to the other connected device. Generally high speed LAN uses star topology.



Advantages of Star Topology

  • It is relatively easy to install and reconfigure.
  • It is robust i.e. if one link fails, the other links are not effect due to it.
  • It is to find problem in this topology.

Disadvantages of Ring Topology

  • One of the biggest disadvantages is its dependency on hub. If hub fails, the whole network is down.

Tree Topology

Tree topology is combination of bus and star topologies. It consists of groups of star topologies connected to a bus which acts as backbone cable. Tree topology is used to expand existing network.



Mesh Topology

In a mesh topology, every device has a dedicated point-to-point link to every other device. Each device is connected to every other device on the network with a separated link, thus it is robust and eliminate traffic problems.



Advantages of Mesh Topology

  • It is robust as each device is connected to other devices through dedicated link, thus eliminating the traffic problems that can occur when links must be shared by multiple devices.
  • It is more secure.
  • Point-to-point links make fault identification and fault isolation easy.

Disadvantages of Ring Topology

  • The large number of cabling and the number of I/O ports required.

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