KB ID 0001347 


This is another question I see getting asked a lot in forums!

You see something like the following;

000032: *Sep 28 09:35:32.507 UTC: %PHY-4-SFP_NOT_SUPPORTED: The SFP in Gi3/0/50 is not supported (PNL-3750-Stack)
000033: *Sep 28 09:35:32.507 UTC: %PM-4-ERR_DISABLE: gbic-invalid error detected  on Gi3/0/50, putting Gi3/0/50 in err-disable state (PNL-3750-Stack)

The usual response is ‘Enable unsupported SFP’s’, and while that sometimes is the answer, it’s not always the answer!



1. Firstly Check the Modules and the Switches, Are you tying to plug a 10GB SFP+ into a slot that only supports SFP, (that includes plugging a twinax cable into an old switch!) In your ‘show run’ you should see TenGigabitEthernet (if your using SFP+ modules). Some switches with network modules list the same interface twice (once as 10GB interfaces and once at 1GB modules, I’ve blogged about that before see THIS ARTICLE, and to confuse things even further, the four interface versions, are grouped as two pairs with each pair consisting of one SFP slot and one SFP+ slot.)

2. Make sure your cable is NOT a CAB-SFP-50CM, (unless you are connecting a 3560 to ANOTHER 3560).

3. Are you using a 2960-S? If so you may need to update the IOS to use SFP+ (assuming your model supports SFP+ not all 2960-S models do).

4. Are you plugging into a Nexus switch with a 1GB connection? If so check the other end for the following error;

Description: Gi1/1/15: This port has been disabled because Non Compliant Gigabit Interface Converter (GBIC) connector detected.

If so, you may need to Manually set the speed on the 5K to 1000, (it wont auto-sense).

5. Is it a non-cisco branded SFP? If so it may still work, (but you will get no joy if you log a TAC call) with the following commands;

Petes-SW(config)#service internal
Petes-SW(config)#no errdisable detect cause gbic-invalid
Petes-SW(config)#service unsupported-transceiver

If you are still in doubt check the Compatibility Matrix.

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Author: PeteLong

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