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New Member

vlan mismatch error


I have investigated and made sure the speed/duplex have been changed between both devices attached to int-faces.

here is my error.

02-ext-liv FastEthernet0/20 (40).

Feb 20 16:22:18.711 PST: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/xx

2900 series switch.

What other approach shall I take to pin point the issue since this is only informational on the error log.


Thanks in advance!


Re: vlan mismatch error


The 'error' message is simply because you have used different VLAN IDs on the access ports at either end. CDP discovers this and logs a warning. The message is pretty harmless in itself.

There are a couple of options to get rid of it:

- configure the access port to be the same VLAN on the two switches at either end of the link

--- OR ----

- enable CDP version 1 on your switches. YOu can do this using: 'no cdp advertise-v2'.

The latter option is simpler and you don't really lose much...

Hope that helps - pls rate the post if it does.



Re: vlan mismatch error

This will not hurt anything , if you want to get rid of it you'll have to match the vlan id on both ends of the link . Say the far end of the link is in vlan 20 , then you have to put your switchports on the 2900 inot vlan 20 also along with the layer3 SVI that you manage the switch with , this would get rid of the message . The switch will work fine even with this message in the log if you do nothing to the switch .

New Member

Re: vlan mismatch error

If your native VLAN on opposite ends of a trunk, you can change it by entering the same command on each end of the trunk:

switchport trunk native vlan XX. Make sure that the native VLAN is significant to your network.

New Member

Re: vlan mismatch error

Thanks to all!! Ialways go by a few rules. No major changes on a FRIDAY and don't it if it's not broken!! lol


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