Customer transmission network consists of OSN 7500. One day, one STM-1 service down. Customer cancelled the "J0 mismatch detection" of the opposite equipment which from other vendor, then service was restored.
Cancelled the "J0 mismatch detection" of the opposite equipent, service restored.
Check the operation log, we found there is "Fiber auto search" ((File-->Search for Filber/Cable) when service down. "Fiber auto search" function is based on J0, it will change J0. But the opposite equipment will insert AIS when J0
When such problem happens, to restore service, you can configure the J0 configuration again, or cancel the "J0 mismatch detection" of the opposite equipent.