1. Check if the physical transmission optical channels run well. Use optical power meter to test the devices at both sides, and the power is in the normal range.
2. Check the negotiation mode of interfaces, and that of both sides is the same.
3. Check if the types of both SFP optical modules are the same. Both are 10KM, and their wavelengths are 1310nm, being the same type.
4. Check the network mode that the interfaces of both boards work. Both boards are of 10G WAN, but that of S8500 is LAN board in default mode; only the port-mode wan command can change Ethernet port to the mode of WAN board.