Monday, November 9, 2020

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 A computer network is a network made up of more than one computer or other hardware device that communicates with each other through

a specific communication system.Computer networks use specific rules and data formats to exchange information that are based on "network programming".The commercial airline reservation system (SABRE) went online in 1960 with two connected mainframes.In 1964, researchers at Dartmouth developed the Dartmouth Price Sharing System giant computer systems for distributed users. Finally that same year, the Massachusetts Institute of Technology (a research group based in General Electric and Bell Labs) used computers as "ROUTERs" to manage telephone connections.During the 1960s, Leonard Kleinrock, Paul Baron, and Donald Davis independently developed network systems that could use packets to network between computer systems.

In 1965, Thomas Marill and Lawrence Roberts G formed the first wide area network (WAN). These were the immediate predecessors of ARPANET, with Roberts later becoming the program manager.
The first widespread use of telephone switches by Western Electric was in 1965, in which computers were actually used for input control.The University of California at Los Angeles, the Stanford Research Institute, the University of California at Santa Barbara, and the University of Utah were connected in 1969 using the 50 kbit / s circuit of the ARPANET network as a start.

X.25 services using commercial were deployed in 1972, and later TCP / IP networks were used as the underlying infrastructure for expansion.Today, computer networks are the key to modern communication. All of these modern public switched telephone networks (PSTNs) are computer powered, and run on the Internet protocol of telephony, although they do not require public internet. Today, communication opportunities have increased significantly over the past decade, and this progressive communication boom would not have been possible without computer networks.

Alternatively, the internal connection of autonomous (uniquely identifiable) computers is defined as a computer network.

Properties of computer networks

Calculation distribution process

Ease of Communication - People communicate efficiently and easily via email using network, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing. Can.

Permits for sharing files, information, and information - Only authorized users can use the information on computers in the network or any other tool for themselves. And share information from their own computer to another authorized user.

Shared Networks and Computing Tools - Computers on the network can access every computer on the network and use shared devices, such as network printers, to print a document on the network. Distributed computing is used to distribute large tasks across a network and use the entire equipment to compute and complete the entire operation.

Can be insecure - Computer networks can be used by computer hackers to spread computer viruses or computer worms that disrupt the functioning of connected devices.

May interfere with other technologies.Can be difficult to set up - Setting up a complex computer network can be difficult. It can be very expensive to set up an effective computer network in a large organization or company.

Communication media

Types of computer networks can be classified according to the hardware used and the associated software technology used to interconnect devices in the network, such as electrical cables (HomePNA, power line communication,, optical fiber, And radio waves (wireless lanes). These levels are shown as 1 and 2 in the OSI model.

The family of well-known mass media is known as Ethernet. It is determined by IEEE 802 and its use enables communication between different standards and media that devices. Wireless LAN technology is designed to connect devices without wiring. These devices are used as a means of transmitting radio waves or infrared signals.

Wire technology

Twisted pair: Wire is a widely used medium for telecommunications. This cable consists of an integrated twisted pair of copper wires that bend in pairs. Normal telephone wire is made up of twisted wires in two insulated copper pairs. A computer networking cable (defined as 802.3 Wired Ethernet by IEEE) is made up of 4 pairs of twisted wires of copper that can be used to transmit both voice and information. Two twisted wires together help to reduce crosstalk and electromagnetic induction. The transmission speed of these wires is from 2 million bits to 10 billion bits per second. Twisted Pair Wires can be divided into two types: Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP): Each pair has several series ratings and different conditions.

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