In order to create a dot1q trunk to an NM-16ESW so that virtual interfaces can be used, must the trunk be created using a standard router fastethernet interface (like fa0/0) and a patch cable to a port on the switch module thus requiring dot1q encapsulation on sub-interfaces?

If that is the case, all switch ports will share the 100 meg uplink and essentially the only thing that the router would be providing is power.

The documentation alludes to "virtual interfaces" and that vlan1 is created automatically. But it doesn't mention anything about running a cable from a router interface to a switch-module port or having to configure the encapsulation or using sub-interfaces.

What am I misunderstanding?

Thanks.