Node (networking)

In communication networks, a node (Latin nodus, ‘knot’) is either a connection point, a redistribution point, or a communication endpoint (e.g. data terminal equipment). The definition of a node depends on the network and protocol layer referred to. A physical network node is an active electronic device that is attached to a network, and is capable of creating, receiving, or transmitting information over a communications channel. A passive distribution point such as a distribution frame or patch panel is consequently not a node.

Computer network nodes

In data communication, a physical network node may either be a data communication equipment (DCE) such as a modem, hub, bridge or switch; or a data terminal equipment (DTE) such as a digital telephone handset, a printer or a host computer, for example a router, a workstation or a server.

If the network in question is a LAN or WAN, every LAN or WAN node (that are at least data link layer devices) must have a MAC address, typically one for each network interface controller it possesses. Examples are computers, packet switches, xDSL modems (with Ethernet interface) and wireless LAN access points. Note that a hub constitutes a physical network node, but does not constitute a LAN network node, since a hubbed network logically is a bus network. Analogously, a repeater or PSTN modem (with serial interface) is a physical network node but not a LAN node in this sense.