How do I get past "SFP Validation Failed" on a SFP-GE-T transceiver on a Nexus 5548UP?
Solution 1:
Configure the port as speed 1000 before inserting the SFP-GE-T transceiver.
If you have the transceiver inserted already, remove it and then set speed 1000 on the port. Upon re-insertion the SFP should come up :)