Introduction to Networking

What is a network?

                    A network is the interconnection of set of devices that are capable of communication.

A device can be a host (or end system) such as Laptops, Computers , Phone, printers etc. or connecting devices such as routers, switch etc.

These devices are connected using wired (cable) or wireless (air) transmission media called Links.

All networks must have :

• A resource to share
• A pathway transfer data (Transmission media)
  
• A set of rules governing how to communicate (Protocols)

Networking criteria

               A network must meet the following criteria

  1. Performance :

                   Performance is measured in 2 ways: Transit time and Response time

• Transit time:

                Time taken by a message to travel from one device to other.

• Response time:

                Time elapsed between inquiry and response. 

Performance of a network depends on :

• No of users
• Type of transmission medium
• Capacity of connected hardware
• Efficiency of software            

 2. Reliability :

                   Reliability is accuracy in delivery. Network reliability is measured by the frequency of failures.                            

  3. Security :

                   Security includes protecting our data from unauthorized access and damage

Data communication 

• Data communication is exchange of data between two devices through a transmission media. Data is exchanged in the form of 0's and 1's.

*A transmission medium is either wired or wireless.

Components of data communication

                A data communication has five components:

   1. Message : Information to be communicated

   2. Sender : Device that sends the message

   3. Receiver : Device that receives the message

   4. Transmission media : Path through which the message travels from sender to receiver

   5. Protocol : Set of rules that governs the data communication 

Modes of Data communication 

1. Simplex mode: 

                  In simplex mode, the data is transmitted in one direction only (Unidirectional). One device sends the data and other device receives the data.

Example : Speaker, Keyboard

2. Half duplex mode :

                  In half duplex mode, the data can be transmitted in both directions but not at the same time.

Example : Walkie-Talkie

3. Full duplex mode :

                  In full duplex mode, data can be transmitted in both the directions simultaneously.

Example : Mobile phones

Types of network connections 

1. Point to point connection:

                 Point to point connection provides dedicated link between two devices.

Example : Television and remote control

2. Multipoint connection:

                 A multipoint connection is one in which two or more devices are connected through a single link.

 

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