Network equipment – devices necessary for the operation of a computer network, such as a router, switch, hub, patch panel, etc. You can distinguish between active and passive network equipment.
Active network equipment – equipment followed by some “intelligent” feature. That is, a router, switch (switch), etc. are active network equipment.
Passive network equipment – equipment not endowed with “intelligent” features. For example – cable system: cable (coaxial and twisted pair (UTP / STP)), plug / socket (RG58, RJ45, RJ11, GG45), repeater (repeater), patch panel, hub (hub), balun for coaxial cables (RG-58), etc. Also, the passive equipment includes wiring closets and racks, telecommunications cabinets.
The main components of the network are workstations, servers, transmission media (cables) and network equipment.
Workstations – network computers, on which network users perform applied tasks.
Network servers – hardware and software systems that perform the function of managing the distribution of shared network resources. The server may be any computer connected to the network, which contains the resources used by other devices in the local network. As the hardware of the server is used quite powerful computers.
Networks can be created with any type of cable.
- Twisted Pair (TP – Twisted Pair)- is a cable made as a twisted pair of wires. It can be shielded or unshielded. Shielded cable is more resistant to electromagnetic interference. Twisted pair is best suited for small institutions. Disadvantages of this cable is a high coefficient of attenuation and high sensitivity to electromagnetic interference, so the maximum distance between active devices in the LAN when using twisted pair should not be more than 100 meters.
- Coaxial cable consists of a single solid or twisted central conductor, which is surrounded by a layer of dielectric. A conductive layer of aluminum foil, metal braid, or a combination thereof surrounds the dielectric and simultaneously serves as a screen against interference. A common insulating layer forms the outer sheath of the cable.
Coaxial cable can be used in two different data transmission systems: without signal modulation and with modulation. In the first, a digital signal is used as it comes from a PC and is immediately transmitted through the cable to the receiving station. It has a single transmission channel with a speed of up to 10 Mbit/s and a maximum range of 4000 m. In the second case, the digital signal is converted into an analog signal and sent to the receiving station, where it is again converted into a digital signal. The signal conversion operation is performed by a modem; each station must have its own modem. This way of transmission is multichannel (enables the transmission over dozens of channels, using only one cable). In this way it is possible to transmit sounds, video signals and other data. The cable length can be up to 50 km.
- fiber optic cable is a newer technology used in networks. The carrier of information is a light beam, which is modulated by the network and takes the form of a signal. Such a system is resistant to external electrical interference and thus a very fast, secret and error-free data transfer of up to 2 Gbit/s is possible. The number of channels in such cables is enormous. Data transmission is performed only in simplex mode, so to organize data exchange devices must be connected by two optical fibers (in practice, fiber optic cable always has an even, paired number of fibers). The disadvantages of fiber optic cable can be attributed to the high cost, as well as the complexity of the connection.
- Microwave radio waves are used as the transmission medium for wireless local area networks or between bridges or gateways for communication between local area networks. In the first case, the maximum distance between stations is 200 – 300 m, in the second case it is a line-of-sight distance. The data transfer rate is up to 2 Mbit/s.
Wireless local area networks are considered a promising area of LS development. Their advantage is simplicity and mobility. Also, problems associated with laying and installation of cable connections disappear – it is enough to install interface cards at workstations, and the network is ready to work.