| 摘要 |
PURPOSE: A loop-back switching method for an AMI(Alternate Mark Inversion)-encoded line in a communication system is provided to prevent that a corresponding port is recognized as a LOS(Loss Of Signal) fault state by local loop-back execution, by using a zero suppression line coding scheme while a local loop-back is executed in the AMI-encoded line and using an AMI line coding scheme while the local loop-back is not executed. CONSTITUTION: If a loop-back control is requested from an upper application(S12), it is judged whether the requested loop-back control is for executing a local loop-back(S12). If the requested loop-back control is for executing the local loop-back, it is set up so that the local loop-back is executed(S14). It is judged whether a ZSCS, for indicating that a non-AMI line coding scheme is used, is set up as '1'(S16). If the ZSCS is not set up as '1', that is, the non-AMI line coding scheme is not used, the ZSCS is set up as '1', so that the local loop-back is executed by the non-AMI line coding scheme(S18). A flag, for indicating that the non-AMI line coding scheme is used because of the local loop-back, is set up as '1'(S18). If the ZSCS is set up as '1', that is, the non-AMI line coding scheme is used, the local loop-back is executed by the non-AMI line coding scheme(S20).
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