In the case of the regeneration station where NS2-to-NS2 cross-connection is configured, if the LOS alarm occurs at the WDM-side optical interface of the upstream NS2 board, it leads to a transient Client_SD alarm at the downstream NS2 board after it clears.
The received signals on the DWDM side of the 3009 chip of the NS2 board are abnormal. After the abnormity is rectified, the DEG alarm is still reported but it clears several seconds later. Although the NS2 board has 3-second anti-jitter function, there stays a small possibility of the DEG alarm. The alarm clears instantly; the NS2 board, however, may consider that SD has occurred on the line and then insert a transient Client_SD alarm to the downstream board. This does not affect switching.