Protection switching in WDM rings using a shared ring switch

摘要

A switching method is provided having improved accuracy in monitoring a network to determine when to switch. The method collects and stores a plurality of bit error rate (BER) values. The BER values are analyzed using a BER hysterisis algorithm to check BER degradation. Thereafter, the method switches a transmission port when the degradation exceeds a predetermined BER threshold level for a predetermined period of time. In another embodiment, a feature which transmits a switch polling signal for a predetermined duration is used with the above switching method.