I have a new 4506 with a SUP 4 engine and a WS-X4418-GB module installed. I want to trunk ISL to five 3560 switches through the GBIC fiber ports on the 4418 module. I can only get the 4506 configured for ISL on the first two ports of the 4418 module. Ports 3-5 will only take dot1.q trunking. Should I be able to use ISL on all ports?