I ran across this while studying for the BCMSN:
"Any untagged frames that an 802.1Q trunk receives will be forwarded to any ports in the native VLAN, which could be a security issue. This issue can be avoided by assigning an unused VLAN number to the native VLAN so that any untagged frames that an 802.1Q trunk receives wil not be forwarded to any user ports."
Looking at some of our switches I see that we are using the user VLAN as the native VLAN but we are also trunking that VLAN.
What effect does that have? Is the user VLAN tagged or not since it is both the native VLAN and it is trunked?