Only offering DHCP service to the network is forbidden, and everyone is using switches to share the pipe coming to the room. I guess routers are ok too if you disable the DHCP server on it first. My 100Mbit switch has worked like a charm, but its getting slow if i want to move huge files from my laptop to the server or desktop. I got the old switch for free so thats the only reason ive been using it.
Worked fine so far.