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I inserted a FET-10G (Fabric Extender Transceiver) SFP transceiver in my Nexus 5548UP and I got "access down" "SFP Validation Failed" in show interface.

FET-10Gs came with my 2232's so I figured they'd be plug and play. This is with a blank port configuration.

How do I get past "SFP Validation Failed" on a FET-10G transceiver on a Nexus 5548UP?

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What version are you running on the 5548? – Joseph Dec 11 '11 at 22:45
This is not a duplicate. Please reopen. The solution for this is different. I know the answer and was trying to get this on ServerFault so other people running into it would have an easy answer available from Google. – Alain O'Dea Dec 13 '11 at 2:26
I also fell for the temptation of just skimming over the text where it says FET-10G here and SFP-GE-T there and wondered for a while why you would want a nearly exactly duplicate question re-opened - the wording is quite similar – the-wabbit Dec 14 '11 at 18:34
Is the solution different between the two? Why not simply update the other question/answer to apply to both? – Zoredache Dec 14 '11 at 20:18
Are you sure it's not counterfeit? Did you check the serial number? – MikeyB Dec 14 '11 at 20:23
up vote 2 down vote accepted

Setting the port's switchport mode to fex-fabric will clear the SFP Validation Failed message. You can do this while the SFP transceiver is inserted.

Example setting up port 1 to allow fabric extension:

int e1/1
switchport mode fex-fabric

The trouble is the order in which I thought this would work. I was trying to verify the transceiver hardware before getting into software configuration of the ports, but the transceiver expects a certain configuration first. This configuration can be changed while the transceiver is inserted.

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