| 摘要 |
The possibility of passing off apparent "good" higher level digital signals that may include corrupted or failed lower level digital signals because of inter-ring grooming of the lower level digital signals from one path-switched ring to another path-switched ring employing at least a first shared node and a second shared node is minimized by dual feeding communications circuits from one pathswitched ring to the other via the shared nodes and by provisioning at least one interring groomed communications circuit from a secondary ring node of one of the shared nodes (secondary communications circuit) of a particular ring to be supplied to a primary ring node in the other shared node of the same ring. The at least one secondary communications circuit is obtained in the primary ring node and demultiplexed so that the lower level digital signals in the at least one communications circuit can be evaluated on a one-to-one pairwise basis with corresponding lower level digital signals in the corresponding at least one communications circuit (primary communications circuit) being supplied from the inter-ring grooming apparatus associated with the primary ring node. The the "best" of the lower level signals in each are selected and are combined into a "new" primary communications circuit which is dual fed in the primary ring node in one direction to its termination ring node and in the other direction through the secondary ring node to the termination ring node. transmission path. A selector in the secondary ring node is revertively biased to normally select the "new" primary communications circuit to be supplied to the termination ring node. However, in the case of a primary communication circuit failure because of an interconnect or other failure in the primary ring node, the selector will then select the secondary communication circuit to be supplied to the termination ring node for the primary ring node. The provisioning of the primary ring node and the secondary ring is such that the demultiplexing to obtain the lower level digital signals, their evaluation and selection, and multiplexing only need to be done in the primary ring node and not in both.
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