How does SDH handle the r_los alarm?

If there is no business, the optical port will reverse or shield the alarm... The possible reason for r_los is: 1. the optical cable is disconnected. In this case, find the optical cable breakpoint and splice the cables. 2. the attenuation of the optical fiber core is too high, and the received optical power is lower than the receiving sensitivity. In this case, you should consider repairing the optical fiber cable or re-jumping the fiber. 3. the pigtail of the inner IDC is broken, and the pigtail fiber is directly replaced. 4. The laser or light receiver is damaged. For optical module or light board .. 5. The peer device loses power.