To my knowledge, the 1638 switches only have Gigabit switch ports gigabit 0/1-48 and then the two high-speed interface slots.
VLANs are assigned to switchports. By default, all switch ports are in access mode on VLAN 1. You have to create and enable VLAN interfaces and assign them as needed to the gigabit switch ports in order to have the equivalent of an ETH 0/1 interface on and of the 1500/1600 switches.
- It is meant to be used for management purposes. It is not a gigabit port like the other switchports on the 1638, but it is seen as its own routable interface in the route table. You could have a route configured to point out the MGMT interface as well.
I hope that answers your question but please do not hesitate to let us know if you have any further questions.