Gotta Love the Physical Layer

By which I don't mean the Physical layer of the OSI 7-layer TCP model. I mean the various physical components of computer networking that are made up of atoms and electrons. For reasons that are beyond me, this is called the Link layer.

Perhaps it should be called the "Is It Actually Plugged In?" layer.

Three days later, and I'm still reading the IT/helpdesk nightmare story thread over on Fark.com. I deeply love the SessionSaver extension for Firefox. It's a seemingly endless parade of stories about clueless users, stupid tech support, and people who physically reshape sensitive electronics in order to attempt to make them fit into someplace they were never designed to go.

Today, one of my machines dropped off the network. It was working just fine yesterday and I haven't so much as touched it in the meantime. So I ping it. "Request timed out". I ping the Big Important Server. Everything's A-OK. So I power cycle the trouble machine and wonder why, if it froze, that it's now correctly going through all its shutdown procedures after I've pressed the power button.

It reboots, and I ping it again. Still nothing. I figure that now it might be something more serious than a simple Windows crash, so I go to the system next to it and prepare to shut it down — I'll need its keyboard, mouse, and monitor to do my diagnostics. Thank God I'm running distributed.net on this one. I pull up a command prompt and type "dnetc --shutdown". Everything's fine. I then type "dnetc --flush". I want credit for those finished blocks! It hangs trying to resolve the IP address of an appropriate dnet server.

At this point, I have it narrowed down to the hub that they both share. The lights look fine. I touch each RJ-45 connector to make sure they're seated. They are.

I go to the next hub down the line and check those connectors, too. Everything is fine. I go back to my dnet machine and open up Internet Explorer. Any page is fine: I pick http://msn.com. And it proceeds to pull up today's MSN cover page.

Uh. That's weird. Ping the trouble machine? Goes through. Everything's working just fine now, and it was all just some sort of flub in the cabling between two hubs.

I blame Gremlins. Sometimes it doesn't take a user to screw up a computer. A network is abundantly capable of sabotaging itself from time to time.