Network Topology

A network topology describes the configuration of a network (how the network components are connected together).

1. Star

The star topology uses a central hub through which all components are connected. In a computer network, the central hub is the host computer, and at the end of each connection is a terminal.

Star Topology diagram

A star network uses a significant amount of cable (each terminal is wired back to the central hub, even if two terminals are side by side several hundred meters away from the host). All routing decisions are made by the central hub, and all other workstations can be simple.

An advantage of the star topology is failure in one of the terminals does not affect any other terminal, how-ever; failure of the central hub affects all terminals.

This type of topology is frequently used to connect terminals to a large time-sharing host computer.

The pros of using Star Topology

• Easy to install and wire.

• No disruption to network when removing or adding computers

• Easy to find problems and to remove it from the network.

The cons of using Star Topology

• Takes more cable

• If central point, the hub fails, then the whole network fails.

• Cost more to set-up

• Bottlenecks at the hub

2. Ring

the ring topology connects workstations in a closed loop. Each terminal is connected to two other terminals (the next and the previous), with the last terminal being connected to the first. Data is transmitted around the ring in one direction only; each station passing on the data to the next station till it reaches its destination.

Ring Topology diagram

Faulty workstations can be isolated from the ring. When the workstation is powered on, it connects itself into the ring. When power is off, it disconnects itself from the ring and allows the information to bypass the workstation.

Information travels around the ring from one workstation to the next. Each packet of data sent on the ring is prefixed by the address of the station to which it is being sent to. When a packet of data arrives, the workstation checks to see if the packet address is the same as its own. If it is, it grabs the data in the packet. If the packet does not belong to it, it sends the packet to the next workstation in the ring.

Ring systems use 4 pair cables (separate send/receive). The common implementation of this topology is token ring. A break in the ring