I have a 3845 with a 4 port hwic installed with 2 vlans running to a switch downstream . They are adding a new "gig" hwic to this 3845 and adding a new Cat 4500 below this . Will I be able to trunk the existing vlans to the new switch or are those restricted to that 4 port fast ether hwic ? I'm guessing no you can;t do that because its not part of that little 4 port switch . Under a tight schedule thats why I am asking here versus trying to set it up in the lab.
Glen, thanks for providing the part number and you are correct. This particular HWIC will behave like a regular routed port that comes with the router. You need to look into the HWIC EtherSwitch family for trunking support without using subinterfaces.
If you look at this list, you can see its category