Specific devices
Network hardware can be classified by its location and role in the network.
Core
Core network components interconnect other network components.
- Gateway: an interface providing compatibility between networks by converting transmission speeds, protocols, codes, or security measures. [9]
- Router: a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination node. [10] It works on OSI layer 3. [11]
- Switch: a multi-port device that connects devices together at the same or different speeds on a computer network, by using packet switching to receive, process and forward data to the destination device. Unlike less advanced network hubs, a network switch forwards data only to one or multiple devices that need to receive it, rather than broadcasting the same data out of each of its ports. [12] It works on OSI layer 2.
- Bridge: a device that connects multiple network segments. It works on OSI layers 1 and 2. [13]
- Repeater: an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances. [14]
- Repeater hub: for connecting multiple Ethernet devices together at the same speed, making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. [1] A hub works at the physical layer (layer 1) of the OSI model [15] and all devices form a single collision domain. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if they detect a collision. Hubs are now largely obsolete, having been replaced by network switches except in very old installations or specialized applications.
- Wireless access point
- Structured cabling
Hybrid
Hybrid components can be found in the core or border of a network.
- Multilayer switch: a switch that, in addition to switching on OSI layer 2, provides functionality at higher protocol layers.
- Protocol converter: a hardware device that converts between two different types of transmission, for interoperation. [16]
- Bridge router (brouter): a device that works as a bridge and as a router. The brouter routes packets for known protocols and simply forwards all other packets as a bridge would. [17]
Border
Hardware or software components that typically sit on the connection point of different networks (for example, between an internal network and an external network) include:
- Proxy server: computer network service which allows clients to make indirect network connections to other network services. [18]
- Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy. [19] A firewall typically establishes a barrier between a trusted, secure internal network and another outside network, such as the Internet, that is assumed to not be secure or trusted. [20]
- Network address translator (NAT): network service (provided as hardware or as software) that converts internal to external network addresses and vice versa. [21]
- Residential gateway: interface between a WAN connection to an Internet service provider and the home network.
- Terminal server: connects devices with a serial port to a local area network.
End stations
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Other hardware devices used for establishing networks or dial-up connections include:
- Network interface controller (NIC): a device connecting a computer to a computer network. [22]
- Wireless network interface controller: a device connecting the attached computer to a radio-based computer network. [23]
- Modem: device that modulates an analog carrier signal (such as sound) to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information. Used (for example) when a computer communicates with another computer over a telephone network. [24]
- ISDN terminal adapter (TA): a specialized gateway for ISDN. [25]
- Line driver: a device to increase transmission distance by amplifying the signal; used in base-band networks only. [26]
