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.[1] 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.
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 a compatibility between
networks by converting transmission speeds, protocols, codes, or security measures.[2]
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.[3] It works on
OSI layer 3.[4]
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.[5] 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.[7]
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[8] 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.
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.[10]
Border
Hardware or software components which 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.[11]
Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy.[12] 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.[13]
Network address translator (NAT): network service (provided as hardware or as software) that converts internal to external network addresses and vice versa.[14]
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.