The Small Things (0x2142)

Even when you’re ten years or so into your career, you can always stand to learn something. It’s important that no matter how experienced you get, you always keep an open mind to other people’s ideas or opinions. As an example to this, I would like to share the story of this blog name.

Back when I worked at a local IT consulting company, they hired a network admin who had worked as several large service providers in the past. He was very experienced and intelligent, and was able to walk into the organization and immediately begin making positive changes. Exactly the type of person that you would want to hire, right?

Well after a few months in, he began checking through some of the equipment we had in our spare store-room. A bunch of Cisco routers and switches, some older than others. After a week, he began complaining about how the devices had sat on the shelves too long. It seemed as though the flash memory was degraded, which caused the devices to not retain their configuration settings. Almost every device he checked through seemed to be experiencing this issue. What else can you do at this point but throw out the bad hardware?

So I decided to pick up one of the devices to see what he was talking about. After all, I was still very early in my career – so if I could stand to learn something from how the devices were behaving, I wanted to see it. So I boot up an old Cisco 2610 router and make a few configuration changes. Save, reboot, and sure enough my changes were gone. However, I had also just been studying how to password reset these devices – since I had a pile of them that needed to be reset. Part of resetting the devices was booting into rommon mode and changing the configuration register value to a hex value of 0x2142.

So what is 0x2142? It’s a hex value that tells the router upon boot to ignore any saved configuration. Of course that easily explained the “degraded flash” issue that the experienced network admin had seen. So I changed the configuration register back to 0x2102, made a few more configuration changes, then rebooted. Sure enough, everything was still there. So I went and told the network admin what I had found. “Oh, checking up on me, huh?”

This story has been a bit of a running joke for a while. But really the importance is that even when you’re extremely intelligent and experienced, you can still overlook simple things. He had been password resetting the devices, but never reverting the configuration register values back to the defaults. Even when you think you might know everything, you should still keep an open mind – because even someone with no experience might have a different view on something. Sure, this wasn’t really a big “save the day” moment, but it helped to show that guy that I had some idea of what I was talking about. From then on, he actually began to work with me on understanding more networking concepts and started asking me to help out with some more of the work he was doing.

What was the most ridiculous simple mistake you’ve made? And how did you find out about it? Share in the comments!