| 摘要 |
Where a stream of data is passed along an intermediate link L1, L2 etc at a higher overall data rate than outside the intermediate link, such as when inverse multiplexing is used in asynchronous transfer mode where a number of low speed data links L1 etc are used to emulate a data link which is higher speed than the original incoming stream of data, the splitting of the data into the multiple streams necessitating the insertion of control packets into the links in order to correct for the disparity in propagation time along the links, the interfaces such as IMA<1> and IMA<2> containing buffers for data packets before transmission down the intermediate links and after reception at the end of the intermediate links, in order to eliminate cell delay variation, which has the result that cells in the output stream can vary by up to two cell positions relative to that in the input cell stream because of the different quantisation of the intermediate link and because of the need to send control packets, arrangements are made for the queue in the input buffer and in the output buffer to be maintained at a constant number of cells, for example by passing information on the input buffer length in the control cells, so that the reconstructed data stream is exactly the same as the incoming data stream, although delayed by a fixed additional two cell delay. <IMAGE> |
