Network Topologies

NETWORK TOPOLOGIES

Bus Topology

All devices share a single communication line/cable. Bus topology may experience problems when multiple hosts send data at the same time, Therefore, Bus topology either uses CSMA/CD technology. Failure of the shared communication line can make all other devices stop functioning.


Both ends of the shared cable have a terminator. The data is sent in only one direction. The terminator prevents signals from bouncing back and causing network errors.

Star Topology

All hosts in Star topology are connected to a central device( hub, switch or router). Each host on the network has a cable segment that attaches the host directly to the central connection point.

 If the central device fails, connectivity of all hosts to all other hosts fails. Every communication between hosts, takes place through only the central device. Star topology is not expensive as to connect one more host, only one cable is required and configuration is simple. Star topology is easy to troubleshoot.

Ring Topology

Each host machine connects to exactly two other machines, creating a circular network structure. A token travels around the ring stopping at each host. If the host wants to transmit data, The host adds the data and the destination address to the token. To connect one more hosts in the network, the administrator may need only one more extra cable.

Types of ring topologies:

• Single-ring.
• Dual-ring.

Failure of any host results in failure of the whole ring.

Mesh Topology

 Hosts are connected to each other. This topology has hosts in point-to-point connection.


Mesh technology comes into two types:

• Full Mesh: All hosts have a point-to-point connection to every other host in the network. It provides the most reliable network structure among all network topologies.
• Partially Mesh: Not all hosts have point-to-point connection to every other host.This topology exists where we need to provide reliability to some hosts out of all.

Hybrid Topology

A network structure whose design contains more than one topology.

The above hybrid topology may contain attributes of Star, Ring, and Bus topologies. Most WANs are connected by means of Dual-Ring topology and networks connected to them are mostly Star topology networks. Internet is the best example of largest Hybrid topology.

References

1. Cisco . (2014). Networks. In: Dave Dusthimer,Mary Beth Ray,Sandra SChroeder IT Essentials PC Hardware and Software Companion Guide. 5th ed. Indianapolis: Cisco Press. 337-374.
   


2. DCN Computer Network Topologies. 2015. DCN Computer Network Topologies. [ONLINE] Available at: http://www.tutorialspoint.com/data_communication_computer_network/computer_network_topologies.htm. [Accessed 01 September 2015].