I have a 802.1q trunk and an ISL trunk conigured between two switches.
When I 'sh int trunk' the output shows the native vlan as 1 for both 802.1q AND ISL ?
Does 'native vlan' have any meaning within ISL ? I don't think it does but just need to confirm.
I think I have verified this in the following way:
I changed the native vlan on one end of each trunk (the 802.1q and ISL) respectfully and CDP only complains about NATIVE_VLAN_MISMATCH for the 802.1q trunk.
Yes you are correct. ISL tags all frames and does not have a concept of a native vlan as such where the native vlan sends packets that do not have a vlan tag.
The native vlan in 802.1q was designed to allow compatability with older switches that did not support tagged frames.