Computer Networks

 Introduction to Networks 

• A Network: A group of devices that can communicate with each other over links.

 • Each device is called a host. Each host has a unique address.

• Network is a connection between two or more devices.

• Which is connected by a communication links.

• A node can be computer, printer or any other devices which is capable of sending and receiving information at each other. 

Example:

INTERNET

• An internet: A network of network or connection between two or more Networks is also known as internet. each host has an address of the form n/h where n is the network number and h is the number of the host on network n.

 

Uses of Network

• It is Used for 

i) Business Application 

ii) Home Application 

iii) Mobile Users 

iv) E-Mail 

Categories or Types of Network

• There are Three Types: 

1. LAN - Local Area Network 

2. MAN - Metropolitan Area Network 

3. WAN – Wide Area Network 

1.LAN - Local Area Network

 A LAN is Designed by Local Area Connections such as:

 i) within Building 

ii) within office 

iii) within Campus 

iv) within Specific 

Advantages : 

 1) Sharing of Files.

 2) Sharing of Programs. 

3) Communication Exchange. 

Disadvantages :

 1) Reliability. 

2) Capacity. 

3) High Cost.

 

2. MAN - Metropolitan Area Network 

A Metropolitan Area Network (MAN) 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 (LAN) but smaller than the area covered by a wide area network (WAN). 

• MAN supports up to 150 Kilometers Distance.

• Example: 

 Telephone Network 

 Cable TV 

Advantages : 

1) High Bandwidth. 

2) It support Large number of Clients. 

3) Reduce the Errors. 

Disadvantages : 

1) Large Space Requirements. 

2) Slower Data Access. 

3) High Cost. 

Components of Network:

1.Client - Which gives the Request.

2.Server - Which gives the Response.
3.Modem - It Indicates Modulator / Demodulator.
4.Router - Which identifies the Path between Client & Server.

5.Channels - Which overcomes the Traffic problems.

Communication Model 

• Data communications are exchange of data between two devices via some transmission medium.

 • It should be done in two ways 

i) Local - It takes LAN Connection. 

ii) Remote - It takes Long distance like MAN & WAN. 

• Data should be Transferred in the form of 0’s and 1’s 

Block Digaram for Communication Model:

Characteristics for Communication Model:

1) Delivery - The System must deliver the data to the correct Destination.

 2) Accuracy - The System must deliver the data at Accurate way.

3) Timeline - The System must deliver the data at Exact Time.

4) Jitter - It refers to the variable in the Perfect Arrival Time.