Types of Network

  Local  Area Network (LAN)

A local Area Network(LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport

The reliability of network is high because the failure of one computer in the network does not affect the functioning for other computers.

For example, a library may have LAN for users to interconnect local devices (e.g., printers and servers) and to connect to the internet.

Addition of new computer to network is easy.

Networks used to interconnect computers in a single room, rooms within a building or buildings on one site are called Local Area Network (LAN).

LAN transmits data with a speed of several megabits per second (106 bits per second).

LAN links computers, i.e., software and hardware, in the same area for the purpose of sharing information.

The main difference between LAN and WAN is the area of the presence of the network.

Local Area Network

Major Characteristics of LAN

Every computer has the potential to communicate with any other computers of the network.

High degree of interconnection between computers.

Easy physical connection of computers in a network.

Inexpensive medium of data transmission.

High data transmission rate.

 

Advantages of LAN

The reliability of network is high because the failure of one computer in the network does not effect the functioning for other computers.

Addition of new computer to network is easy.

High rate of data transmission is possible.

Workstations can share peripheral devices like printers. This is cheaper than buying a printer for every workstations.

Software can be shared, software packages are stored on the server and downloaded to workstations as requested.

When a new version comes out, it only has to be loaded onto the server instead of onto every workstation.

Messages can be sent to people working at other computers on the network which can save time and paper.

Data can be shared because database files stored in the server are available to users around the network

 

Disadvantages of LAN

Special security measures are needed to stop users from using programs and data that they should not have access to.

Networks are not very easy to set up and need to be maintained by skilled technicians.

Printing can be slow. Where a lot of workstations are served by only one or two printers, long print queues may develop.

A virus can spread more easily. If a virus gets into one computer, it is likely to spread quickly across the network because it will get into the central backing store.

If the server fails, all the workstations are affected. Work stored on shared hard disk drives will not be accessible and it will not be possible to use network printers either.

Because networks can be complicated to maintain, a network manager may be need to be employed to run the system.

If the file server develops a serious fault, all the users are affected, rather than just one user in the case of a stand-alone machine.

 

 

Metropolitan Area Network(MAN)

A metropolitan area network(MAN) is a network that connects two or more local area networks or campus area networks together

A metropolitan area network (MAN)  could link buildings within a city.

Does not extend beyond the boundaries of the immediate town/city.

Routers, switches and hubs are connected to create a metropolitan area network.

Thus it is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network but smaller than the area covered by a wide area network

Sometimes referred to as a campus network

Metropolitan Area Network

 

Wide Area Network (WAN)

A wide area network(WAN) is a computer network that covers a broad area (i.e. any network whose communications links cross metropolitan, regional, or national boundaries .

For example, for a large company the head quarters might be at Delhi and regional branches at Bombay, Madras, Bangalore and Calcutta.

Here regional centers are connected to head quarters through WAN.

The distance between computers connected to WAN is larger

A WAN is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country)

 

What is a WAN?

A Wide Area Network (WAN) is a computer network used to exchange information over a wide geographical area. It can be situated within several countries or even worldwide. Larger than a LAN, it can use phone lines or satellites as transmission media. In some cases, linking together some LANs forms a WAN.

Wide Area Network

 

Major Characteristics of  WAN

Communication Facility: For a big company spanning over different parts of the country the employees can save long distance phone calls .Computer conferencing is another use of WAN where users communicate with each other through their computer system.

Remote Data Entry: Remote data entry is possible in WAN. It means sitting at any location you can enter data, update data and query other information of any computer attached to the WAN but located in other cities. For example, suppose you are sitting at Madras and want to see some data of a computer located at Delhi, you can do it through WAN.

Centralized Information: In modern computerised environment you will find that big organizations go for centralized data storage. This means if the organization is spread over many cities, they keep their important business data in a single place. As the data are generated at different sites, WAN permits collection of this data from different sites and save at a single site.

Types of WAN

Leased Line

Circuit Switching

Packet Switching

Cell Relay

Wireless WAN(WWAN)

 

Advantages  of  WAN

Covers a large geographical area so long distance businesses can connect on the one network

Shares software and resources with connecting workstations

 

Disadvantages  of  WAN

Cost of data transmission in LAN is less because the transmission medium is owned by a single organization. In case of WAN the cost of data transmission is very high because the transmission medium used are hired, either telephone lines or satellite links.

The speed of data transmission is much higher in LAN than in WAN. The transmission speed in LAN varies from 0.1 to 100 megabits per second. In case of WAN the speed ranges from 1800 to 9600 bits per second (bps).

Data transmission errors that occur in WAN are more compared to LAN.

Setting up a network can be an expensive and complicated experience. The bigger the network the more expensive it is.

Security is a real issue when many different people have the ability to use information from other computers. Protection against hackers and viruses adds more complexity and expense.

Once set up, maintaining a network is a full-time job which requires network supervisors and technicians to be employed.

Network Scale  :

Interprocessor Distance        Processors located in            Example of Networj

10m                                                            same room                                                                 LAN

100m                                                        same building                                                            LAN

1 km                                                        same campus                                                            LAN or CAN

10 km                                                       same city                                                                      MAN

100 km                                                   same country                                                        WAN

1000 km                                                   same continent                                                    WAN

10000 km                                                     same planet                                                     Internet

LAN, WAN, MAN

 

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