| 摘要 |
A depacketizer is used in terminating an ATM multiplexed data stream at a functional unit, virtual channel data being carried in cells in the data stream. The depacketizer has a plurality of cell buffers each storing the data contained in a single cell and being loaded in the sequence of a message sequence number carried by each cell and emptied in accordance with a depacketizer algorithm to form a data stream. A fill-in cell format generator causes, on the failure of a valid cell to arrive, the replacement of the missing cell by a fill-in cell in the data stream. A time-out function generator is started after each cell has been depacketized and sometimes after fill-in replacement cells have been generated. A cell frame aligner has the depacketizer with a frame alignment signal detector which detects a frame alignment signal in the non-continuous data stream and generates an associated frame start signal and a loss of frame alignment signal as appropriate. A frame aligner accepts the non-continuous data stream and its associated frame start signal, except in the presence of a loss of frame alignment signal and aligns the non-continuous data stream to clock and frame start signals of the functional unit. |
