After we configure 155M services on OSN equipments, if these services don’t be used, OSN equipments will report RLOS and AUAIS alarms. However, recently, a customer said they used SPQ4 and SEP1 boards of OSN3500 configure 155M services, alarms that OSN3500 reported were strange. When all the ports of SPQ4 and SEP1 boards were loop-back with cable, some trails reported AUAIS, some trails reported HPUNEQ and HPTIM, even for some bidirectional services, AUAIS was reported from A to B, HPUNEQ and HPTIM were reported from B to A. The customer queried why the same situation (loop-back with cable), but 155M services reported different alarm.
The customer undid all loop-back, then loop back again, AUAIS was only alarm in all trails.
When 155M services are configured but no real 155M services transmitted by it, if we don’t loop back the ports of SPQ4 or SEP1 boards, then, SDH boards will report AUAIS; if we loop back the ports, there are two kinds of situation.
1. If 155M services are configured before loop-back, AUAIS will be reported, even loop back the ports.
2. If 155M services are configured after loop-back, AUAIS or HPUNEQ/HPTIM is possible, it lies on distance between two stations, even time of downloading the configuration. If the distance is large, probability of AUAIS is large; on the contrary, HPUNEQ/HPTIM is large. However, whether AUAIS or HPUNEQ/HPTIM, as long as undo loop-back, only AUAIS is reported, then loop back again, only AUAIS exists.