Devices that mediate data transmission in a computer network
Networking hardware, also known as network equipment or computer networking devices, are electronic devices that are required for communication and interaction between devices on a computer network. Specifically, they mediate data transmission in a computer network. Units which are the last receiver or generate data are called hosts, end systems or data terminal equipment.
Networking devices includes a broad range of equipment which can be classified as core network components which interconnect other network components, hybrid components which can be found in the core or border of a network and hardware or software components which typically sit on the connection point of different networks.
The most common kind of networking hardware today is a copper-based Ethernetadapter which is a standard inclusion on most modern computer systems. Wireless networking has become increasingly popular, especially for portable and handheld devices.
Taking a wider view, mobile phones, tablet computers and devices associated with the internet of things may also be considered networking hardware. As technology advances and IP-based networks are integrated into building infrastructure and household utilities, network hardware will become an ambiguous term owing to the vastly increasing number of network-capable endpoints.
Network hardware can be classified by its location and role in the network.
Core network components interconnect other network components.
Gateway: an interface providing a compatibility between networks by converting transmission speeds, protocols, codes, or security measures.
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. It works on OSI layer 3.
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. It works on OSI layer 2.
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.
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. A hub works at the physical layer (layer 1) of the OSI model 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.
Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy. 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.
Network address translator (NAT): network service (provided as hardware or as software) that converts internal to external network addresses and vice versa.
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.