From Earlham Cluster Department
The path from LittleFe to the Outside World™ is somewhat convoluted, but should be fairly static once running. Each of the eight (8) nodes plugs into the sixteen (16) port Netgear switch.
This switch is then uplinked on port 16 to the Linksys router/WAP. All the nodes use DHCP to get an IP address, DNS server information, and the gateway IP address from the Linksys unit. The Linksys stores the MAC address and the associated IP address in a table, which was generated from the static information by sequentially powering up each unit. In the event of the loss of this table, new IP addressses will be assigned starting from 192.168.1.9. An rwho daemon is installed on each machine that can be used to figure out the new IP addresses of each machine.
The Linksys is used to provide NAT'd gatewaying to the Outside World™ for both the cluster, and any other equipment plugged into its internal switch, the Netgear switch, or wireless users that are connected to it. The wireless is set to Wide Open, and the ESSID is set to LittleFe. The unit supports RADIUS authentication, which might be an avenue for future security.