We have 6504 connected to the other end 3560G switch through 1000M LX SPF. I keep seeing the FCS and Runt errors in the giga port at 6504. The other end 3560G port is clean all the time. I changed the SPF module, still same issue. Changed the fiber from the patch panel to 6504. No help.
As I understand if I only see the receiving errors in 6504, that means only one fiber direction (3560G to 6504) has problem. Since 3560G doesn't have any receiving errors, it means the direction from 6504 to 3560G is clean.
I will try different patch panel port to see what will be changed. But is there any other troubleshooting I can take for this issue based on your experience?
Thanks a lot!