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Point-to-Point Communications

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Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

A point-to-point connection is a dedicated communication link between two systems or processes. Think of a wire that directly connects two systems. The systems use that wire exclusively to communicate. The opposite of point-to-point communications is broadcasting, where one system transmits to many.

A telephone call is a circuit-oriented, point-to-point link between two phones. However, calls are usually multiplexed across telephone company trunks; so, while the circuit itself may be virtual, the users are engaging in a point-to-point communication session.

An end-to-end connection refers to a connection between two systems across a switched network. For example, the Internet is made up of a mesh of routers. Packets follow a hop-by-hop path from one router to the next to reach their destinations. Each hop consists of a physical point-to-point link between routers. Therefore, a routed path consists of multiple point-to-point links. In the ATM and frame relay environment, the end-to-end path is called a virtual circuit that crosses a predefined set of point-to-point links.

A shared LAN such as Ethernet provides a form of point-to-point communications. Keep in mind that on shared LANs, all nodes listen to signals on the cable, so broadcasting is supported. However, when one node addresses frames to another node and only that node receives the frames, one could say that the two nodes are engaged in point-to-point communications across a shared medium.

Point-to-multipoint connections are possible over multidrop links. A mainframe and its terminals is an example. The device that provides the multipoint connection is usually an intelligent controller that manages the flow of information from the multiple devices attached to it.

Point-to-point communications is defined in the physical and data link layers of the OSI protocol stack.

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
All rights reserved under Pan American and International copyright conventions.