Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Patent
1996-05-01
1998-06-16
Olms, Douglas W.
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
370351, H04L 1256
Patent
active
057682720
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention refers to an NT2 unit for an ATM network of claim 1.
The designation ATM (asynchronous transfer mode) refers to a wide band communication technology in the range of approximately 10 to 622 Mbit/s. A kind of packet transfer is concerned wherein said packets have a uniform length and comprise an address part (header) as well as an information part (payload). These packets are currently referred to as cells.
Central switching centers for ATM networks are e.g. known from the documents EP-A-299 473 and WO91/13505. These switching centers or nodes direct the cells arriving on various lines to the required outgoing lines under control of the addresses of the cells, and prevent congestions.
Today, extensive norms concerning the structure and the interfaces of ATM networks exist. There is a division into a public domain and a private domain of the ATM network. So-called Network Terminations type 1 (NT1) serve as interface units between these areas, any kind of Terminal Equipment (TE) being connectable to each NT1 on the private side. A Network Termination type 2 (NT2) is defined for the connection of a plurality of terminal equipments of the same user. By this definition, the required basic functions and intersections U, T, and S are essentially determined.
In a general manner, low-priced and universally applicable structural units are desired for the construction of ATM networks. It is therefore an object of the invention to provide an economical NT2 unit for arbitrary applications in the private domain of an ATM network.
SUMMARY
This object is attained by the present invention, which pertains to an NT2 unit (17) for an ATM network (10). The ATM network (10) is divided into a public domain (11) and a private domain (15), wherein two well-defined intersections U, T and NT1 units (19) (Network Termination type 1) form a border between the domains (11, 15). The public domain (11) comprises switching nodes (12) and transmitting paths (13), whereas the private domain (15) comprises different kinds of terminal equipment (16) and NT2 units (17) (Network Termination type 2). Cells comprising a header and a payload are used for transmission of information between the terminal equipment (16). The terminal equipment (16) are connected to the NT1 units (19) or to the NT2 units (17), while the NT1 units (19) are connected to the switching nodes (12). The NT2 units (17) are connected to the NT1 units (19). The NT1 units (19) comprise at least two mutually opposed transmission paths (23, 24) for the cells and comprise two identical input/output circuits (22.1, 22.2) for the connection of the switching nodes (12) and of the terminal equipment (16), respectively.
The NT2 units comprise at least one switching unit (39) and a connecting and control unit (40), these units (39, 40) being interconnected in a loop configuration via two mutually opposed lines (123, 124). Each of the switching units (39) comprise at least two mutually opposed transmission paths (23, 24) common to the NT1 units (19), three identical input/output circuits (22.1, 22.2, 22.3) common to the NT1 units (19), an extractor (31) and an inserter (32). The two transmission paths (23, 24) are connected via a first (22.1) and a second (22.2) of the three input/output circuits to the lines (123, 124) of the loop configuration. The third (22.3) of the three input/output circuits is connected to the terminal equipment (16). The extractor (31) is inserted into a first (23) of the two transmission paths, and is connected to the third input/output circuit (22.3) and is designed for the controlled deviation of cells from the first transmission path (23) to the third input/output circuit (22.3). The inserter (32) is inserted into a second (24) of the two transmission paths, and is connected to the third input circuit (22.3) and is designed for the controlled multiplexing of the cells from the third input/output circuit (22.3) onto the second transmission path (24).
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in more deta
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Takase et al., "ATM Transport Node for Flexible and Robust Access Networks" IEEE Global Telecommunications Conference In Houston--Globecom '93 Technical Program Conference Record, vol. 3 of 4, pp. 1481-1487, 29 Nov. 1993, N.Y., New York, USA.
"SwitchMAN--Switch-based ATM Gigabit MAN and Customer Premises Network" IBM.RTM. Technical Disclosure Bulletin, vol. 36, No. 11, Nov. 1993, pp. 263-264, Armonk, New York, USA.
"Shared-Medium-Based Subscriber Ring Access to ATM Networks" IBM.RTM. Technical Disclosure Bulletin, vol. 37, No. 4b, Apr. 1994, pp. 241-244; Armonk, New York, USA.
Potts Martin
Rao Sathyanarayana
ASCOM Tech AG
Olms Douglas W.
Patel Ajit
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