I have a 3750 with a port configured as an access port in vlan 109. Connected to this port is 3550 switch - all ports is vlan one.
On the 3750 I get messages to the effect that a Native VLAN mismatch is detected between the 2 switches. It seems to be cosmetic, as there are no apparent problems. Should the switch report this error even though the port is not a trunk?
That error message is generated by CDPv2 and is not a cause for concern. You can disable CDP version 2 to get rid of the message.
Hope that helps - pls do rate the post if it does.
We had the same problem between a 3400me and a 3550. Turned out certain IOS had a cdp bug which would cause these error messages. An IOS upgrade on our switches fixed the messsage. But like you already stated this is mostly cosmetic and others have mentioned just disabling cdp on the ports as access ports do not pass vlan info anyways and the switches won't care. Probably the easiest thing to do since it does not require an IOS upgrade.