I have manage the Ethernet network for an apartment building that consists of a 50Mb circuit, 7204VXR router, and five Catalyst 3548XL switches. This building is full of users that love to connect wireless routers "backwards" into the LAN and backfeed DHCP into the network and screw everything up. Is it possible to configure the 3548 switches to suppress this behavior? If not, what is the cheapest switch model (on the refurb market) to gain this functionality. Thanks!