| 摘要 |
<p>The NT2 (Network Termination type 2) unit comprises a terminal and control unit and an arbitrary number of identical switching units (39) which are interconnected in a loop configuration by means of two connecting lines (123, 124). Similarly to an NT1 (Network Termination type 1) unit, each of said switching units (39) comprises two mutually opposed transmitting paths (23, 24) for ATM (Asynchronous Transfer Mode) cells as well as two input/output circuits (22.1, 22.2) to which said connecting lines (123, 124) are connected. Said switching unit (39) further comprises a third input/output circuit (22.3) allowing the connection of terminal equipment. Finally, it is provided with an extractor (31) and an inserter (32) which are inserted in said transmitting paths (23, 24) and are connected to said third input/output circuit (22.3) via connecting lines (35.1, 35.2). According to address indications contained in the cells, said extractor (31) directs incoming cells either to the second or to the third input/output circuit (22.2 resp. 22.3). Said inserter (32) multiplexes incoming cells to the first input/output circuit (22.1). The switching unit (39) thus provides a switching facility operating in one direction which allows a clear arrangement and a flexible and economical production of the NT2 unit.</p> |
