Issue Description
the 25GE port couldn't come up when connect Huawei CE6865-48S8CQ-EI switch to a CISCO switch with a SFP-25G-SR transceiver. There is no physical link visible on switch LEDs, from the transceiver information, we can see both TX and RX power.

The transceiver information is as follows:
<huawei>dis interface 25GE1/0/10 transceiver verbose
25GE1/0/10 transceiver information:
Common information:

Transceiver Type :25GBASE_SR

Connector Type :LC

Wavelength (nm) :850

Transfer Distance (m) :70(50um/125um OM3)

100(50um/125um OM4)

30(50um/125um OM3)(no rs fec)

40(50um/125um OM4)(no rs fec)

Digital Diagnostic Monitoring :YES

Vendor Name :HUAWEI

Vendor Part Number :02311KNR

Ordering Name :

Manufacture information:

Manu. Serial Number :*********

Manufacturing Date :2018-11-26

Vendor Name :HUAWEI

Alarm information:

Diagnostic information:

Temperature (Celsius) :45.86

Voltage (V) :3.32

Bias Current (mA) :6.94

Bias High Threshold (mA) :20.00

Bias Low Threshold (mA) :0.50

Current RX Power (dBm) :-0.95

Default RX Power High Threshold (dBm) :5.40

Default RX Power Low Threshold (dBm) :-13.30

Current TX Power (dBm) :-0.54

Default TX Power High Threshold (dBm) :5.40

Default TX Power Low Threshold (dBm) :-11.40

Handling Process
Regarding such issue, it is always caused by the mismatched paramter between 2 sides. Regarding 25GE port, the FEC mode can be a possible reason.

we try to change the FEC mode to base-r on Huawei side, then all the 25GE ports can come up. it means that that the FEC mode is mismatched between Huawei and CISCO.

Root Cause
The FEC mode is mismatched between Huawei and CISCO.

Solution
change the FEC mode to base-r

Suggestions
regarding port issue, it is always caused by the incorrect parameter, we can try to change them and see if it can work, such as, negotiation type, FEC mode, speed, etc.