| 摘要 |
<p>In a duplicate active-standby memory unit arrangement (100), a resynchronization initiation determination is made on a cell-interval-by-cell-interval basis based on the equality of cell contents of corresponding queues in the active (101) and standby (102) memory units. If an inequality of the cell contents of the corresponding queues in the active and standby memory units occurs during any cell interval, resynchronization may be initiated. In an embodiment, the lengths of data in corresponding queues, i.e. the number of cells stored in the corresponding queues, in the active and standby memory units are compared (by 105,106,107,108) on a cell-interval-by-cell-interval basis. If the number of cells stored in any of the queues is different from the number of cells in its corresponding queue in the other of the memory units during any cell interval, resynchronization of the memory units is initiated. In another embodiment of the invention, the outputs (114-1,115-1) of corresponding queues in the active memory unit (101) and the standby memory unit (102) are compared (by 117) on a cell-interval-by-cell-interval-basis. If the result of the comparison indicate that any one or more of the queues outputs in one of the memory units is different from the output of the corresponding queue in the other memory unit, resynchronization is initiated. Robustness of the latter comparison algorithm is enhanced by restricting the comparisons to cell intervals during which the queue outputs in the active and standby memory units do not both include idle cells. Additionally, robustness of the resynchronization initiation is further enhanced by simultaneously employing both the comparison of cell length in the queues and the comparison of the queue output contents to detect when to initiate resynchronization. <IMAGE></p> |
