| 摘要 |
PURPOSE: A transceiver unit for discriminating fixed and variable bit rate cells is provided to discriminate fixed bit rate cells and variable bit rate cells, transmitted and received between an ATM network and a PSTN, and economically and efficiently transmit and receive them. CONSTITUTION: A transceiver unit for discriminating fixed and variable bit rate cells consists of an MPU(1), a cell separating/gathering part(2), an SONET framer(3), an E1 framer(4) and a memory(5). The MPU(1) generates variable bit rate cells and sends them to the SONET framer(3). The MPU(1) receives cells from the SONET framer(3), judges whether they are variable bit rate cells or fixed bit rate cells, and determines their path. In case that the variable bit rate cells from the MPU(1) and the fixed bit rate cells generated from the E1 framer(4) are transmitted, the cell separating/gathering part(2) gathers them and transmits them to the SONET framer(3). At this moment, the cell separating/gathering part(2) transmits the fixed bit rate cells generated from the E1 framer(4) preferentially. If the seventh bit of the third byte of a received ATM cell header is '1', the cell separating/gathering part(2) transmits the cell to the MPU(1). If it is '0', the cell separating/gathering part(2) transmits the cell to the E1 framer(4).
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