Data Communication – Notes

Data Communication Notes and Important Points

• Data communication refers to the exchange of data between two or more networked or connected devices like laptops, PC, printers, routers etc.
• Sender, receiver, messages, channel and protocols are major components of data communication.
• In data communication, transmission media are the links that carry messages between two or more communicating devices. These are broadly classified into guided and unguided media.
• In guided transmission, there is a physical link made of wire/cable through which data in terms of signals are propagated between the nodes. These are usually metallic cable, fiber-optic cable, etc. They are also known as wired media.
• In unguided transmission, data travels in air in terms of electromagnetic waves using an antenna. They are also known as wireless media.
• The capacity of channels is measured in bandwidth. The unit of bandwidth is Hertz.
• Communication can be done in three different modes — simplex, half-duplex, and full-duplex communication.
• Switching techniques are alternative to dedicated lines whereby data is routed through various nodes in a network. It forms a temporary route for the data to be transmitted. Two commonly used switching techniques are – circuit switching and packet switching.
• Electromagnetic spectrum of frequency ranging from 3 KHz to 900 THz is available for wireless communication. This spectrum range (3KHz to 900THz) can be divided into four categories- Radio waves, Microwaves, Infrared waves and Visible or Light waves, according to their frequency ranges.
• Bluetooth is a short-range wireless technology that can be used to connect mobile-phones, mouse, headphones, keyboards, computers, etc. wirelessly over a short distance.
• Based on the architecture of the mobile network, mobile communication technologies are classified into different generations identified as 1G, 2G, 3G, 4G, and 5G.
• In communication, protocol is a set of standard rules that the communicating parties — the sender, the receiver, and all other intermediate devices need to follow. Flow control, access control, addressing, etc. are examples of protocol.
• HTTP stands for HyperText Transfer Protocol. It is the primary protocol used to access the World Wide Web, which was developed by Tim Berners- Lee at CERN in 1989.
• File Transfer Protocol (FTP) is the protocol used for transferring files from one machine to another. Like HTTP, FTP also works on a clientserver model.
• Point-to-Point protocol (PPP) defines how two devices will authenticate each other and establish a direct link between them to exchange data.
• TCP/IP stands for Transmission Control Protocol/ Internet Protocol. It is a set of standardised rules that uses a client-server model of communication in which a user or machine (a client) requests a service by a server in the network.

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