MA5600T; V800R006C31B059, ONT: EchoLife HG850a V100R001C01B017,Nwtwork structure: ONT－> MA5600T(GPBC)－> Switch －>AX4000(traffic generator)－>ONT. When do the ONT DEMO, we found some FCS error in the downstream, but there is no packet loss.
As there is only FCS error, we think it is physical line problem.
1, Change the optical spliter from two level to one level, the problem remains.
2, Change teh GPBC board and other type of ONT, the problem remains.
3, Change the uplink port from switch to AX4000, the problem remains.
4, To check if it is software problem, collect the configuration and AX4000 test result.
5, When the customer to remove the devices we found the cable between ONT and AX4000 has some problem. The order of the cable is not OK, so we changed another cable and test again. The problem disappears.
As the order of network cable has some problem, there is no packet loss but FCS error.
When there is FCS error but no packet loss, please check the physical line first, if there is no problem in the physical, then check the configuration or software.