blocking dhcp



i've got a legit dhcp server on my network. i've got a 3550 as my vtp server providing 4 vlans to 4 2950 switches. if somebody were to plug into one of those vlans with a dhcp server configured then it would throw off my whole network. how could i block the dhcp server that could plug into the 2950 switch? i'm using cisco switches running ios 12.1

you probably need to look at the port based traffic control of the switches to do this, specifically port blocking and storm control.

if you don't have the guides to hand you can get them at http://www.cisco.com

see thats what i thought but i was told because ports are at layer three and the switch is at layer two that you could not use any type of port blocking... that is what i thought of first... but i'm going to browse cisco to see still... thanks.