| 摘要 |
In a duplicate active-standby memory unit arrangement, a resynchronization initiation determination is made on a cell-interval-by- cell-i nterval basis based on the equality of cell contents of corresponding queues in the acti ve and standby 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 queu es, in the active and standby memory units are compared on a cell-interval-by-cell-inte rval basis. If the number of cells stored in any of the queues is different than the number of cells its corresponding queue in the other of the memory units during any cel l interval, resynchronization of the memory units is initiated. In another embodim ent of the invention, the outputs of corresponding queues in the active memory unit and the standby memory unit are compared on a cell-interval-by-cell-interval basis. If the results of the comparison indicates that any one or more of the queue output s 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 enchanced by restricting the comparisons to cell interva ls during which the queue outputs in the active and standby memory units do not bot h 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 ini tiate resynchronization.
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