Networks

Networks Notes

• PAN= Panoral Area Net 
• LAN= Local Area Net
• MAN= Metropolitan Area Net
• WAN= World Area Net

Computer networks

Acomputer network is a set of computers connected to each other so they can share resources and exchange 
information.

We can divide computer networks into three categories, depending on their size:

1. Local area networks or LANs
2. Metropolitan area networks, made up of several LANs
3. Wide area networks, covering a country or continent.

LANs can also be categorised according to the way in which the different machines are are connected to each 
other.

Elements in a network

All computer networks have a logical component, which is an operating system and applications that work on a 
network, and a physical component connecting the different computers to each other.

Each computer needs an adaptor or networkcard to send information to the other computers and receive 
information back.

Thehub distributes all of the information it receives between the other computers in the network.

It can be replaced by a switch, which sends the data it receives onñy the recipient.

This information travels down a transmission medium, normally a cable similar to a telephone wire with 
an RJ45 connector the end.

Coaxial and fibre optic cables are also used.

https://www.youtube.com/watch?v=ZvWn5xBflUs

Activities

We have looked at the advantages of using computer networks.

Can you think of any disadvantages? Write them in your exercise book. 

• It poses security difficulties. Because there would be a huge number of people who would be using a computer network to get and share some of their files and resources, a certain user’s security would be always at risk. 

• If a computer network’s main server breaks down, the entire system would become useless. 

• It allows for more presence of computer viruses and malware. There would be instances that stored files are corrupt due to computer viruses. Thus, network administrators should conduct regular check-ups on the system, and the stored files at the same time.

• Though computer networks are said to be an inexpensive system when it is already running, its initial set up cost can still be high depending on the number of computers to be connected.

 

Wireless Networks

Wireless networks, known as WLANs (Wireless LAN’s), use electromagnetic waves to transmit data. 
All computers need to have a wireless network card.

Networks with a combination of wired and wireless devices use wireless access points (WAP) that we 
can use to transmit data through wires or electromagnetic waves.

Shared Internet access

Computers in a network can share a single Internet connection. Computer networks can connect to 
the Internet in two ways:

Internet Connection Sharing(ICS), where all communication is through one computer that must 
be switched on all time.

Using a router, which detects data and directs it to and from the internet.

One disadvantage of network sharing is that the computer with all the elements must be switched on 
at all times so that the other users access those elements.

To overcome this problem, we can use network storage systems and print servers.

Activities

1. In your exercise book, draw a diagram of a local area network made up of two computers with 
   wired connections and  two with wireless connections. 
   
   
2. Use the Internet to find out what Bluetooth technology is. Bluetooth is an industrial specification 
   for Wireless Personal Area Networks (WPAN) created by Bluetooth Special Interest Group, Inc. 
   that enables the transmission of voice and data between different devices through a radio link 
   in the ISM band of 2.4 GHz.

Glossary

Connector: a device for joining electrical circuits together (sometimes known as ports, plugs, or interfaces)

coaxial: is a cable used to transport high-frequency electrical signals that has two concentric 
conductors, one central, called core, in charge of carrying information, and one external, tubular 
aspect, called mesh, shielding or braid, which serves as a reference for ground and return of currents.

Fibre optic: is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair.

Electromagnetic wave: one of the waves that are propagated by simultaneous periodic variations of electric and magnetic field intensity and that include radio waves, infrared, visible light, ultraviolet, X-rays, and gamma rays.