Node (networking)

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A node (Latin nodus, ‘knot’) is a critical element of any computer network. It can be defined as a point in a network at which lines intersect or branch, a device attached to a network^[1], or a terminal or other point in a computer network where messages can be transmitted, received or forwarded.^[2]

A node can be any device connected to a computer network. Nodes can be computers, personal digital assistants (PDAs), cell phones, switches, routers or various other networked devices.

[edit] Role of nodes in networking

A node is a connection point, either a redistribution point or an end point, for data transmission. In general, a node has programmed or engineered capability to recognize and process or forward transmissions to other nodes.

If the network in question is a LAN or WAN, every node must have a MAC address if it is at least a data link layer device, as defined in the OSI model. In the Internet, many network nodes are host computers, identified by an IP address, and all hosts are nodes. However, datalink layer devices such as switches, bridges and WLAN access points do often have an IP host address (except sometimes for administrative purposes), but are considered as network nodes.

If the network in question is a peer-to-peer or overlay network, nodes that actively route data for the other networked devices as well as themselves are called supernodes.

In telecommunications, a node is a specific location in a telecommunication network. In cable television systems (CATV), this term has assumed a broader context and is generally associated with a fiber optic node. This can be defined as those homes or businesses within a specific geographic area that are served from a common fiber optic receiver. A fiber optic node is generally described in terms of the number of "homes passed" that are served by that specific fiber node.