I have 2 4500 series switches on a flat LAN and the rest of my switches are 3com.. I want to setup VMPS to manage all of the switches using dot1q, is this possible with 3com in the mix?
Moreover VMPS is MAC address based. So you really have to collect all MAC addresses in your network and creating the DB which maps MAC address to VLAN.
It can be done in small network manually but you have to use some URT for larger network.
Best solution is 802.1x based solution. Juniper has one product UAC which works on this and gives you lot of control over the network and as usual it is not properitary, you can control any machine on any damn vendor switch.