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. •
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. •
Bridge: a device that connects multiple
network segments. It works on
OSI layers 1 and 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. 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 Hubs are now largely obsolete, having been replaced by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. •
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.
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 that allows clients to make indirect network connections to other network services. •
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. •
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 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. •
Wireless network interface controller: a device connecting the attached computer to a radio-based computer network. •
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. •
ISDN terminal adapter (TA): a specialized
gateway for ISDN. •
Line driver: a device to increase transmission distance by amplifying the signal; used in base-band networks only. ==See also==