- Network cards are controllers plugged into the expansion slots of the computer’s motherboard, designed to send signals into the network and receive signals from the network.
Terminators are 50 ohm resistors that attenuate the signal at the ends of a network segment.
- Hubs are central devices in a cable system or physical star topology network that, when a packet is received on one of its ports, forwards it to all the others. The result is a network with a logical shared bus structure. A distinction is made between active and passive hubs. Active hubs amplify received signals and transmit them. Passive hubs pass the signal through without amplifying or recovering it.
- Repeater – A network device that amplifies and reshapes an incoming analog network signal to the distance of another segment. A repeater acts at the electrical level to connect two segments. Repeaters do not recognize network addresses and therefore cannot be used to reduce traffic.
- Switches are software-driven central devices in a cable system that reduce network traffic by having the incoming packet analyzed to find out the address of its destination and transmitted accordingly only to it.
Using switches is more expensive, but also a more productive solution. A switch is usually much more complex and can handle several requests at the same time. If for some reason the desired port is busy at the moment, the packet is placed in the buffer memory of the switch, where it waits for its turn. Networks built with the help of switches can cover several hundred machines and have a length of several kilometers.
- Routers – standard network devices operating at the network layer and allowing forwarding and routing packets from one network to another, as well as filtering broadcast messages.
- Bridges – Network devices that connect two separate segments, limited by their physical length, and carry traffic between them. Bridges also amplify and convert signals for another type of cable. This allows you to expand the maximum network size while not violating limitations on the maximum cable length, number of devices connected, or number of repeaters per network segment.
- Gateways – Hardware and software complexes that connect heterogeneous networks or network devices. Gateways allow you to solve the problem of different protocols or addressing systems. They operate at the session, representative and application layers of the OSI model.
- Multiplexers are central office devices, which support several hundred digital subscriber lines. Multiplexers send and receive subscriber data over telephone lines, concentrating all traffic into one high-speed channel for transmission to the Internet or company network.
- Firewalls (firewall, firewalls) – network devices that control incoming and outgoing information to and from the local network and protect the local network by filtering information. Most firewalls are based on classic access control models in which a subject (user, program, process or network packet) is allowed or denied access to a particular object (a file or network node) on presentation of a certain unique element unique to that subject. In most cases, this element is a password. In other cases, this unique element is a microprocessor card, biometric characteristics of the user, etc. For a network packet, this element is the addresses or flags in the packet header and some other parameters.