In a communications network, a network node is a connection point that can receive, create, store or send data along distributed network routes. Each network node -- whether it's an endpoint for data transmissions or a redistribution point -- has either a programmed or engineered capability to recognize, process and forward transmissions to other network nodes.
The concept of network nodes came into being with the use of distributed networks and packet switching. Depending on its application, network nodes perform a variety of functions.
In data communications, physical network nodes include data communications equipment or devices that sit between data terminal equipment (DTE) and data transmission circuits. These include switches, bridges, modems or hubs that perform signal conversion, coding and line clocking. Network nodes in data communications also include data terminal equipment like digital telephone handsets, printers or host computers like routers, servers or workstations.
Internet network nodes
In internet and intranet networks, most physical network nodes are host computers that are identified by an IP address. Some data link devices like wireless local area network (WLAN) access points do not have IP host addresses and are considered physical network or LAN nodes rather than internet nodes or hosts.
Local area network and wide area networks
In local area networks (LANs) and wide area networks (WANs), a network node is a device that performs a specific function. Each node needs to have a MAC address for each network interface card (NIC). Examples include modems with Ethernet interfaces, wireless LAN access points and computers. If a device is offline, its function as a node will be lost.
Telecommunications network nodes
In fixed telephone networks, nodes may be public or private telephone exchanges or a computer providing an intelligent network service. In cellular communications, nodes include base station controllers that control one or more base stations. Cellular network base stations are not considered nodes.
Cable television system nodes
In cable systems, nodes have taken on a broader context and are generally associated with fiber optic cable that connects to businesses or homes served by a common fiber optic receiver within a geographic area. In cable systems, a fiber optic node describes the number of homes or businesses passed that can be served by a specific fiber node.