Basic question about ethernet management port vs switch IP

[burkechris1]

I'm a little confused... I just set up a Catalyst 2650-X which has an ethernet management port. Express setup wanted a switch IP, and said management port IP address was optional. I gave the switch an IP address in the main VLAN,  and the built-in device manager web site loads, and that all works fine. But what I don't understand is, why does the switch need an IP? Why wouldn't I just want an IP address for the ethernet management port, and use that to manage all the ports and VLANs?

[Danny Morris]

I do not use the setup wizard, so I cannot address that. 

Typically, the management IP is the address you will use to access the device. The main VLAN address will probably be your default gateway for the devices on that VLAN. It is true that they could be the same (depending on how you have your access-lists set up) but for security reasons, it may be best to not only use different addresses, but also have them on separate VLANS.