Why we need computer networks

Computer networks help users on the network to share the resources and in communication. Can you imagine a world now without emails, online news papers, blogs, chat and the other services offered by the internet?

The following are the important benefits of a computer network.

File sharing:

 Networking of computers helps the users to share data files.

Hardware sharing:

 Users can share devices such as printers, scanners, CD-ROM drives, hard drives etc.

Application sharing: 

Applications can be shared over the network, and this allows to implement client/server applications

User communication: 

Networks allow users to communicate using e-mail, newsgroups, and video conferencing etc.

Network gaming:

 Lot of games are available, which are supports multi-users.

Network Topologies

 Network Topologies:- 

A network topology is the physical layout of computers, cables, and other components on a network.

 There are a number of different network topologies, and a network may be built using multiple topologies.

 The different types of network layouts are Bus topology, Star topology, Mesh topology, Ringtopology, Hybrid topology and Wireless topology. 

Bus Topology

Bus Topology

A bus topology consists of a main run of cable with a terminator at each end. All nodes like workstations, printers, laptops servers etc., are connected to the linear cable. The terminator is used to absorb the signal when the signal reaches the end, preventing signal bounce. When using bus topology, when a computer sends out a signal, the signaltravels the cable length in both directions from the sending computer. When the signalreaches the end of the cable length, it bounces back and returns in the direction it came from. This is known as signal bounce. Signal bounce will create problem in network, because if another signal is sent on the cable length at the same time, the two signals will collide. 

Advantages of Bus Topology

• Easy to connect a computer or peripheral to a linear bus.

• Requires less cable length than a star topology.

Disadvantages of Bus Topology

• Entire network shuts down if there is a break in the main cable.

• Terminators are required at both ends of the backbone cable.

• Difficult to identify the problem if the entire network shuts down.

• Not meant to be used as a stand-alone solution.

Star Topology

A star topology is designed with each node (like workstations, printers, laptops servers etc.,) connected directly to a central network hub/switch. Each workstation has a cable that goes from the network card to network hub or switch.

Advantages of Star Topology

• Easy to install and wire.

• No disruptions to the network then connecting or removing devices.

• Easy to detect faults and to remove parts.

Disadvantages of Star Topology

• Requires more cable length than a linear topology.

• If the hub fails, nodes attached are disabled.

• More expensive than linear bus topologies because of the cost of the devices.