A computer network is a group of several computers connected to each other by network equipment.
The computer network provides:
- Collective processing of data by users
- Data exchange between users
- Software sharing
- Sharing peripherals (printers, modems, etc.).
Classification of computer networks
- geographical area: global, regional, corporate, local
- in the field of application: household, office, industrial
- topology: bus, ring, star, tree
- behind the transmission medium: symmetrical cable, coaxial cable, twisted pair, fiber optic cable, infrared, microwave radiation.
- a set of protocols.
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Local networks with a maximum distance between nodes of no more than a few km.
Global networks covering the territory of the country, several countries with a distance between individual nodes of thousands of kilometers.
Regional networks – networks of the scale of the city, area, area, etc.
Corporate networks of the company — combining several local networks using telephone, satellite or other channels of the global network into a single network of the company.
The network topology determines the physical location of computers, cables, and other network components.
Main topologies: direct cable connection, bus, star, ring.
Direct cable connection
So you can connect only two computers, there are many restrictions, so this type of connection is used only for temporary connection of two PCs.
All computers connect to the main cable using network adapters. All of them have equal access to the main cable. The more computers on the bus, the slower the network. The main drawback: if the trunk cable is damaged, the entire network stops working. Advantage: easy organization, easy connection of new workstations. An example of such a network is a local area network built on thick or thin coaxial cables, which serve as the backbone cable to which all PCs are connected.
Star topology all computers are connected via cable segments to the Central component (hub, switcher) In terms of reliability, this type of topology is the best. The entire network will fail only if the Central component fails. An example of such a network is any modern local network with the use of a hub as a Central element, segment cables are twisted pair.
Ring topology all computers are connected in a ring one by one pair of cables. Information is passed sequentially between adapters workstations. If at least one computer fails, the entire network will cease to function (although there are networks in which this deficiency is eliminated). This is a major drawback of this network. An example of such a topology would be an FDDI network.