During a network reconstruction, an OSN3500 data was downloaded from T2000 to NE. After that SPQ4 boards on that equipment reported C4_R_LAISD alarm. Customer reported that VC4 services from those boards were broken.
To solve the problem the SPQ4 interface should be configured as 155 Mbps. To configure follow these steps:
1. Open NE-EXPLORER
2. Select the SPQ4 board.
3. -> Configuration
4. -> SDH Interface
5. -> On the working mode column select 155M SDH Mode
SPQ4 board can be used for 155 Mbps or 140Mbps services. SPQ4 interfaces should be configured to 155 or 140 Mbps according to customer requirements. In this case all the interfaces of this board were configured to 155 Mbps, but after the download it was changed to 140 Mbps.
C4_R_LAISD is a high order alarm; in this case, on the source the service was configured as 155 Mbps and on the sink was configured as 140Mbps.
Be careful with SPQ4 after a NE download or reset because the working mode is changed automatically to 140 Mbps PDH Mode. It will affect services.