Networking

The Three Topologies

1st Toplogy - Star Topology

The star network

In a star network each device on the network has its own cable that connects to a switch or hub. A hub sends every packet of data to every device, whereas a switch only sends a packet of data to the destination device.

The advantages of a star network are:

  • it is very reliable – if one cable or device fails then all the others will continue to work
  • it is high-performing as no data collisions can occur

The disadvantages of a star network are:

  • it is expensive to install as this type of network uses the most cable (network cable is expensive)
  • extra hardware is required (hubs or switches) which adds to cost
  • if a hub or switch fails, all the devices connected to it will have no network connection

2nd Topolgy - Ring Topology

The Ring Network

In a ring network each device (workstation, server, printer) is connected to two other devices - this forms a ring for the signals to travel around. Each packet of data on the network travels in one direction and each device receives each packet in turn until the destination device receives it.

Advantages and disadvantages of a ring network

This type of network can transfer data quickly, even if there are a large number of devices connected because the data only flows in one direction, so there won’t be any data collisions. However, the real disadvantage is that if the main cable fails or any device is faulty, then the whole network will fail.

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3rd Topology - Bus Topology

The Bus Topology

In a bus network all the workstations, servers and printers are joined to one cable (the bus). At each end of the cable a terminator is fitted to stop signals reflecting back down the bus.

Advantages and disadvantages of a bus network

The advantages of a bus network are:

  • it is easy to install
  • it is cheap to install, as it doesn't require much cable

The disadvantages of a bus network are:

  • if the main cable fails or gets damaged the whole network will fail
  • as more workstations are connected the performance of the network will become slower because of data collisions
  • every workstation on the network "sees" all of the data on the network – this is a security risk
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