CDP is generating that message and there is a native vlan mismatch found on the port. Native vlan is a vlan whose frames are sent as untagged. By default the native vlan is 1 on the cisco switches.
If someone has changed the native vlan to something else on one side of the link then you will get this kind of message. Now to check the native vlan on the port, use command " show interface x/y switchport ".
To change the native vlan on the switchport
int fa x/y
switchport native vlan
Or you can simply disable the CDP on the port and it will not log you that message.
well each switch has a native vlan assigned to it with the Cisco default being 1.
Somehow either by you or someone else with access (or you installed a grey market switch that didnt have the defaults reset to it.) The default vlan was changed on this switch or an adjoining cisco switch. This would be seen by CDP CDP is proprietary cisco (Cisco Discovery Protocol))and unless specified by a 'no cdp' command on a switchport all cisco switches will look out all ports (maybe just all trunk ports Ill have to look that up) looking for CDP peers and if they see another peer with a different default vlan it will give this error. To correct this either change the default vlan on the offending switch or do a no cdp on the port that the offending switch connects to on this switch.
Hi everyone, I would like to thank you in advance for any help you can provide a newcomer like myself!
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