NetBoot Across Subnets for Mac

From Mike Bombich:

The NetBoot process begins with the client broadcasting a request for a NetBoot server. Typically, routers block broadcast traffic, thus limiting clients to booting to NetBoot servers that are within thier subnet. If you have a hundred servers laying around, this is no big deal as you can place one on each subnet. For the rest of us, there is "NetBoot Across Subnets". The name says it all, it essentially configures a client's startup parameters to avoid the broadcast request and boot directly to a NetBoot server, in the same subnet, or across campus. But wait, there's more! NBAS can also create a package installer + postflight script. The package doesn't install any files, but the postflight script sets the startup parameters to NetBoot to a specific server and reboots the computer. This is ideal for use with Apple Remote Desktop -- select the computers that you want to NetBoot, install the NBAS package and voila, they reboot from your NetBoot server.