Nexus 5000 FEX ports show 'sfp validation failed' with FET-10G modules
The poster runs a Cisco Nexus 5000 with an N2K-C2232PP-10GE fabric extender. Three FEX-facing ports report 'sfp validation failed' with Cisco FET-10G modules. Following advice found online, the module was removed, the port speed set to 1000 and the module reinserted; the port was also shut/no shut and several different modules were tried, but the error stayed. After pulling the module the port did not even report as empty until another module had been inserted and removed, and the port LEDs blinked amber. 'switchport mode fex-fabric' was already configred on the interfaces. The poster asked what else could cause the validation failure.
- Hardware: Cisco Nexus 5000, Cisco Nexus 2232PP fabric extender (N2K-C2232PP-10GE)
- Transceivers: FET-10G, SFP-10G-SR
- Form factor: SFP+
Symptoms / messages:
sfp validation failed
down (Transceiver validation failed)
port LED blinking amber
port not reported as empty after module removal
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Comments 5
The most common cause is a wrong port speed left over from earlier access/trunk use, which can also surface only after a reboot. Remove the FEX association ('no channel-group', 'no fex associate', 'switchport mode access', 'shutdown'), set 'speed 10000', then re-add 'switchport mode fex-fabric', 'fex associate <id>', 'channel-group <n>' and 'no shutdown'.
Make sure the interface is configured with 'switchport mode fex-fabric'.
Try the 'service unsupported-transceiver' and 'no errdisable detect caause gbic-invalid' commands.
I had an interface stuck in 'down (Transceiver validation failed)' and fixed it by swapping the module type: FET-10G is only valid on fabric-extender uplinks, while SFP-10G optics are needed for regular data ports.
I cleared the same error by taking the port out of its forced mode, shutting it down, explicitly configuring 'speed 10000' to match the connected bandwidth, and bringing it back up with 'no shutdown'.