Networking hardware

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 device that connects devices together 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.
• Bridge: a device that connects multiple network segments. It works on OSI layers 1 and 2.[6]
• 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 and 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] Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects 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 Hubs are now largely obsolete, having been replaced by network switches except in very old installations or specialized applications.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 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.[9]
• 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]

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]
• 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.

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.