What is Data Communication and Computer Network?
Data Communication is the process of exchanging digital data between two or more computers that act as source and receiver through wireless media or transmission media such as a wire cable. This Data communication process goes through a telecommunication network known as Computer Network that allows computers to exchange data.
Classification of Computer Networks
Computer Networks get classified on the following factors:
- Geographical Span – Geographically, a network is spanned in the following categories: LAN, PAN, MAN, and WAN.
- LAN (Local Area Network): This network is a connection of two or more personal computers spanned in a small area such as building, office through a communication medium such as twisted pair cable, coaxial cable, etc.
- PAN (Personal Area Network): This network is spanned for personal use of computing devices (mobile phones, laptops, media player, and play stations), arranged within a person, typically within a range of 10 meters such as Bluetooth, Wi-Fi, USB, etc., and covers an area of 30 feet.
- MAN (Metropolitan Area Network): This network is inter-connection of different LANs, covers a larger geographic area, uses between banks, and colleges in a city and airline reservation through a telephone exchange line.
- WAN (Wide Area Network): This network spans over a large geographical area through a telephonic line, fiber optic cable or satellite links used in the sectors of Business, Government, and Education. The Internet is a broad network in the world.
- Inter-connectivity: Components of a computer network may be connected either physically or logically or in both manners as defined below:
- Mesh Topology in which every single device connected to every other device on the network.
- Bus Topology in which all devices connected to a single medium by lacking geographical connection.
- Linear Structure in which each device connected to its left and right peers only.
- Star Topology in which all devices connected with a single device in the form of a star.
- Hybrid Topology in which two or more topologies combined.
- Administration: As an administrator’s point of view, a network can be private (a single autonomous system that can’t be accessible outside its physical or logical domain) or public (can be accessed publically).
- Architecture: Computer Network Architecture is the complete framework of physically and logically designed software, hardware, protocols, and media of the transmission of data that defines how computers organized and how tasks allocated to them.
There are various types in which computer networks discriminate as below:
- Peer-to-Peer Network: This type of network model forms a small environment of up to 10 computers by linking them together with equal privilege and responsibilities for data processing without any dedicated server.
- Client/Server Network: This is a client-server based network model that enables clients to access the resources like audios, videos from the Server. Clients are all the computers or end users that communicate with each other through a server. The Server is the central computer or central controller that makes a response to the clients ‘request and secures, manages the computer network.
- Hybrid Network: This network model is the combined architecture of the network models defined above.
Components of Computer Network
NIC: Network Interface Card (NIC) is a physical network interface defined as the hardware component that enables a computer to connect to a network. It is in used for both wired and wireless connections. It is also known as network interface controller card, expansion card, network card, computer circuit board, Network Adapter Card (NAC).
Hub: A computer network hub is a basic type of wired network device by which multiple connected computers can communicate via broadcast communication.
Switch: Switch is a computer hardware component that is used to connect multiple devices on a computer network. Its features are more advanced than hub features.
Router: Router is a networking device used to connect a LAN with an internet connection that forwards data packets between computer networks.
Modem: A modem ( MOdulator /DEModulator ) is a hardware device used to transmit digital data over transmission media like a telephone line, a cable or a satellite etc.
Cables and Connectors: Cable is a transmission media used for transmitting digital signals. Optical-Fibre Cable, Co-axial cable, and Twisted Pair Cable are the three types of cable used for transmission of digital signals.
The transmission mode is the way of data transmission from one device to another device. It is of three types:
- Simplex Mode: In simplex mode, data flows in a single direction making communication unidirectional means a device can only send the data but cannot receive it or vice-versa.This transmission mode used in business sectors like sales that do not require any corresponding reply and also used in a simplex channel like a radio station in which signals are transmitted to the listeners not allowing them to transfer back. Keyboard and monitor are examples of devices used in simplex transmission.
- Half-Duplex Mode: In half-duplex mode, data flows in both the directions but not at the same time, and its path can reverse. During data transmission, the entire bandwidth can utilize in a single direction at the same time. A Walkies-talkie is the best example of Half-Duplex Mode in which one person speaks and another listens such that they both can’t communicate simultaneously.
- Full-Duplex Mode: In Full-Duplex mode, data flows in both the directions making the communication bi-directional like a telephone network in which two persons communicate with each other through a telephonic line such that both of them can speak and listen simultaneously. It is the fastest mode of communication between devices as it doubles the utilization of the capacity of the communication channel.
Security and Privacy
These are the following aspects of Network Security to achieve secure communication as follows:
- Privacy: Privacy concerns provide confidentiality to both the sender and the receiver for secure connection having data transmission strategy (i.e., encryption and decryption methods) such that transmitted messages sent by the sender (first party) will be sent only to the intended receiver (second party) preventing from the snoopers (third party).
- Message Integrity: Message integrity ensures authenticity to the sender and receiver for the transmitted data sent over communication such that the content of transmitted messages will not be tampered with or altered during transmission, either maliciously or network trouble, in transit.
- End-point Authentication: It ensures receiver the authentic identity of the sender, i.e., the messages not sent by any deceiver.
- Non-Repudiation: Non-Repudiation is a legal concept defined as an assurance that someone can’t deny the validity of something he/she given. In network security, it assures receiver with the proof of the origin of data and data integrity. By this assurance, a sender can’t deny for the messages he or she sent to the receiver.