Quote Originally Posted by retro77 View Post
Put the gaming network on a separate IP range than the File Sharing network.

Gaming: 10.0.0.0/255.255.255.0

File Sharing: 192.168.0.0/255.255.255.0

Don't set a default gateway on the one with no internet connection [File Sharing hopefully].
If you do that without physically separating the networks all you'll do is prevent one logical network from seeing the other. The hardware will actually have to cope with more traffic this way (twice the network management overhead) and end up being just as (if not more) congested. It also assumes the control software in the switches can cope with more than one connected subnet, which is normally the job of a router.

Think of this like building a cluster. You need two separate networks, one for gaming (command and control) and one for file sharing (data transfer). In this case not every machine needs to be connected to both networks at the same time but each kind of traffic needs to be confined to it's own network, logically (IP addresses) and physically (cables and switch). Another possibility might be to add a wireless access point (or two) to free up some of the switch ports and cables.