computer networks

Computer Networks

By Aayush Gala

Grade 8

What is a computer network?A network connects several nodes or networking devices together. This allows sharing of resources such as printers, storage memory, etc.

Different Types of Networks• LAN (Local Area Network)

Also includes WLAN (Wireless LAN)

• WAN• MAN

In this presentation we will only be looking at LAN, WAN and WLAN.

LAN (Local Area Network)• It is a small network with a maximum

coverage of about a few buildings. • Allows sharing of printers, medium sized

files, etc. • Mainly used in offices and schools.• Advantages: sharing of resources, communication

increases, controlled by an administrator.• Disadvantages: malware threat, queues, slower

access to external networks, lesser data security compared to stand alone computers, if there is a break-down of a node then the network will brake.

Topologies of LAN

• Bus Topology• Ring Topology• Star Topology

Bus TopologyComputers are connected to a main line

Data moves towards the destination node

A Terminator is often used here. It is a device used at the ends of the main line to avoid signal bounce which can lead to data interference.

(continued)Advantages: easy to add new node, entire network will not get affected with the failure of one node, less cables required, cost efficient.

Disadvantages: if main line malfunctions the entire network will fail, more nodes will decrease speed, difficult to isolate a fault on a particular device or computer.

Ring TopologyIt’s a chain of nodes cabled together to form a loop/ring.

Each computer receives data only relevant to it as each computer has a unique identification number.

(continued)Advantages: functions efficiently even with heavy data load, suitable for larger networks.

Disadvantages: networks can fail of there is a cable fault, addition of new node is difficult as it has to be placed between existing ones.

Star TopologyEach node is connected to each other by a hub or a switch.Every node has its own connection to the hub.Advantages: if one node fails the entire network is not affected, easy to work on a faulty node and isolating it, network can be easily expandedDisadvantage: break down of hub will lead into full network crash

Hub/Switch

WAN(Wide Area Network)

A network over a large area such as cities, countries, etc.

Connected by a router or a modem

Expensive because of additional hardware and operating system

E.g.: Internet

WLAN (Wireless Local Area Network)Communication is made over short distances with either radio or infrared signals instead of cables.Ranges of different signals• Radio: 30-50 metres• Infrared: 1-2 metresA device called Access Point is connected to such networks.Advantages: all computers can access that same material, less cabling, flexibility, adding new device is easy.Disadvantages: big security threat if network is unprotected, signals can be interfered with, transfer rate is less

Network DevicesModem (Modulator Demodulator): converts digital signals in to analogue signals (modulation) and vice versa (demodulation).

Network Hub: connects numbers of nodes from where it receives of one device and sends it to all devices.

Switches: connects numbers of nodes from where it receives data and sends it to the relevant node.

Routers: used to connect networks together and to the Internet.

THANK YOU!