Subnets

As is the case in most universities, "Campus Technology" is an empire, with the point of view that it's their network and the faculty and students are, grudgingly, permitted to make occasional use of it. Everything is locked down tight and even something as simple as installing a little freeware ap requires two techs and paperwork and log sheets and proof that it's legit and so on.

Fortunately, Southern Man is in the Department of Computer Science. The advantage isn't what you think - his knowledge of computer networking is no greater than yours - it's that many of his students are peons in Campus Tech so he has people on the inside. The benefits - admin rights to his own desktop, the ability to print on the color printer upstairs, unofficial knowledge of a few of the secret user accounts and passwords, and so on - makes life a little easier.

Now, last fall we (Dr. A, Dr. S, and Dr. Southern Man) built a LittleFe mini supercomputer for academic use. And ever since we got it home and set up in an office just a few feet from the computer lab it has been an endless struggle to get it to work. Every week last spring we'd be huddled over that thing, as often as not with one of the guys from Campus Technology, trying to diagnose communications problems. If the LittleFe boards could talk to each other, it couldn't reach the network. If the head board could talk to the network, it couldn't see the other boards. And these problems crop up in the lab as well. We often boot the lab PCs with BCCD, a piece of software that turns the computers into a Linux cluster, but one particular computer - the instructor station - could never join the network.

So we're fussing with this and getting nowhere when the little-seen Director of Networking wanders by and asks what we're doing. We and the techs explain our problems. He nods and says "The instructor station is on a different subnet than the rest of the lab."

What about the room where we have LittleFe?

"Yeah, different subnet from the labs."

Southern Man doesn't know what's worse - three network ports within twenty feet of each other that serve the same department all on different subnets or Campus Tech's inability to figure this out over a six-month period.