Topologies

A network topology describes how the nodes in a network are connected together.

Bus:

Advantages:

• • It's cheap as it doesn't require a switch or expensive networking equipment.

  • It requires less cable than other topologies.

Disadvantages:

• • If a single node on the network fails the entire nework stops working.  This also means that it can be very difficult to locate faults on the network.  E.g. If the network card on a single computer stops working, the network administrator would need to check each network card in each computer, one at a time, to find the faulty card.

  • Since all the nodes on the network share a common 'cable', traffic congestion can become a problem.  The more nodes on the network the worse the problem becomes.

Star:

Advantages:

• • Reliability: If one node fails it does not affect the rest of the network. 

  • This also means that maintenance is easy.  Nodes can be repaired, replaced, added or removed without issue.

  • Easy to find faulty nodes as only faulty node's network connectivity will be affected.   

Disadvantages: 

• • If the switch or hub fail the entire network will fail.

  • Since each node has its own cable running to a central point, much more cable is required than other topologies.

Ring:

Advantages:

• Data only travels in one direction along a ring at very high speed.  This means that collisions are unlikely.

  • Performance is better than the bus topology especially when there are many nodes or high traffic volumes.

  • Each computer has an equal chance to transmit data 

Disadvantages: 

• • Each packet of data must travel around the entire network making it slower than the Star Topology (when switches are used instead of hubs)

  • If a single node fails the entire network fails

  • The network cards / devices used to connect nodes to a ring topology network are relatively expensive.

References:

[1] Linear Bus Topology (n.d.) (Online Image) Available at: http://fcit.usf.edu/network/chap5/pics/linebus.gif (Accessed: 27 February 2013)

[2] The Star Topology (n.d.) (Online Images) Available at: http://media.bestofmicro.com/Local-area-network-LAN-installation,Y-3-308379-13.jpg (Accessed: 27 February 2013)

[3] ianswer4u.com, Bus Topology : Advantages and Disadvantages (n.d.) (Online) Available at: http://www.ianswer4u.com/2011/05/bus-topology-advantages-and.html#axzz2M5EpJpGO (Accessed: 27 February 2013)

[4] Katherine Lady Berkeley's School, Lan Network Topologies (n.d.) (Online) Available at: http://www.klbict.co.uk/gcse/theory/5_3/5_3_4_topologies.htm (Accessed: 27 February 2013)

[5] ianswer4u.com, Ring Topology: Andvantages and Disadvantages (n.d.) (Online) Available at: http://www.ianswer4u.com/2011/05/ring-topology-advantages-and.html#axzz2MHOEfU2h (Accessed 01 March 2013)