Browse Prior Art Database

Digital PBX Supporting Star Connection

IP.com Disclosure Number: IPCOM000042706D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Norstedt, BE: AUTHOR [+2]

Abstract

A PBX (Private Branch Exchange) is normally designed to establish point-to-point connections between subscribers, allowing them to communicate in pairs. A voice and data PBX can, in addition to serving normal telephone calls, also connect data equipment together pair-wise. For many types of data equipment, such as display terminals, the traffic pattern is not point-to- point, however. Normally a large number of terminals want to communicate with only one or very few processors. The traffic pattern is thus star-shaped instead of point-to-point. A digital PBX can be designed to support star-shaped traffic in addition to normal point-to-point traffic, as described in the following section. The figure above shows the principle. Subscribers 7, data and telephone, are connected to the PBX.

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Digital PBX Supporting Star Connection

A PBX (Private Branch Exchange) is normally designed to establish point-to- point connections between subscribers, allowing them to communicate in pairs. A voice and data PBX can, in addition to serving normal telephone calls, also connect data equipment together pair-wise. For many types of data equipment, such as display terminals, the traffic pattern is not point-to- point, however. Normally a large number of terminals want to communicate with only one or very few processors. The traffic pattern is thus star-shaped instead of point-to-point. A digital PBX can be designed to support star-shaped traffic in addition to normal point-to-point traffic, as described in the following section. The figure above shows the principle. Subscribers 7, data and telephone, are connected to the PBX. Inside the PBX l a high speed data link 4, working in TDM (time division multiplex) mode of operation, connects the subscribers (voice and data) pair-wise with one another. A Front End Processor 3 (FEP) is connected to this link or to a separate high speed link 2. The FEP link is also operating in TDM mode, allocating one time slot to each terminal, communicating with one of the main processors. The FEP is connected to the main processors 6 via channels or communication links 5. The FEP perfoms the following functions: - It allocates time slots on the TDM line for the terminal-to- main processor communication in cooperation with the logic assoc...