A few weeks ago I noticed that our network hub was getting disturbingly hot, so I started turning off the power strip when we weren’t home. After returning from San Diego, the first time we turned the computers back on, the hub started buzzing. However, it stopped after a few seconds.

So I should have thought of the hub immediately when the network started acting up today.

I had been on and off the computer and the net all morning with no noticeable problems, and Katie had been on for just a few minutes when it stopped loading websites.

The players involved:

  • My computer, the homebrew Linux system
  • Katie’s computer, the Mac G4
  • The shared laptop (a PowerBook, not hooked up initially)
  • The DSL modem
  • The consumer-grade mini-router
  • The ethernet hub
  • Lots of cables

Initial troubleshooting:

  1. Modem lights: all good.
  2. Load a site from homebrew: check.
  3. Ping G4: check.
  4. Reset router: check.
  5. Connect to router config: uh…. come on…

It was about that point that I looked at the hub and saw the insane amount of traffic apparently going between one of the computers and the router, along with a high number of collisions. Powering the hub off and back on didn’t seem to make a difference. Once I determined it was my computer, I disconnected it from the hub, and Katie was able to reach the web.

OK, so I’d found out what was preventing the G4 from connecting. Now I had to figure out what was going on. The traffic didn’t show up on any network monitors, and nothing seemed to be running to generate it. I started shutting services down one by one. No change. I logged off. No change. I deactivated the network and dropped to single-user mode. No change.

So I turned the machine off. Traffic stopped. (Good.) But the network card was chattering even when it was supposed to be inactive, which suggests either it was in some funny mode or it was broken. I hoped it was just some funny mode, because I really didn’t want to have to replace it. Aside from the whole disassembly process, it’s a combination USB2/Firewire/Ethernet card, so I’d need to either find another with the same combination or get a separate USB2/Firewire card… and I couldn’t remember whether there were enough free slots.

Power on. The insane network chatter started up during the BIOS check! There was no operating system running, and it was saturating the connection! Fine, I disconnected the computer and started trying to figure out whether it was something I could fix, or whether I’d have to replace the card.

At this point I pulled out the laptop and hooked it up so that I’d be able to do some troubleshooting online. But the weird thing was, the same bizarre traffic pattern was going on between the router and the laptop. Again, no sign of any network hogs actually on the system. I started to get suspicious.

I hooked my system back up to the network, watched the hub go insane, and then disconnected the router. Now, the ridiculous traffic was going between my computer and the laptop!

So here’s the situation:

  • One device (the G4) seems okay.
  • Of three other devices (including the connection to the Internet), any two cause the network to be flooded.
  • What’s left that hasn’t been changed? The hub

Fortunately, I never got rid of the old 10-baseT hub when we went to 10/100. I dug it out of the closet, hooked up all the computers to it instead of the faster one, and you know what? Everything worked.

So now we need to head over to Fry’s or someplace and pick up a new hub. I’m hoping to find a wireless access point that has enough physical ports, because then we only need to get one device. (We want to go wireless for the laptop, but the other machines — with the possible exception of the G4 — still need cables.)

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