We have a campus with 16 buildings and older 850nm 1Gbps fiber links between the buildings, that all come to a core switch for our servers that also uses 1Gbps ports. We're finally starting to replace our aging 10/100 end-user switches, and much of what we're looking at are 1 Gbps units.

My question is, since the trunk/uplink lines are still 1Gbps, if I were to install 1 Gbps switches for end users, should I limit the ports to 100Mbps until I can also upgrade the trunks to avoid allowing a bad-behaving host to saturate a trunk line (since we're a college, we have plenty of mis-behaving hosts) and thereby create a DoS situation for a building, or will TCP congestion control typically take care of that for me? What if we have a lot of UDP traffic (games, video chats, even a small amount of bittorrent)?