Cater Hero

Lessons Learned: Theory vs Practice

September 1st 2011

There is a big difference between knowing about something, knowing how to use that something, and knowing how to use that something well. Many people deal with this trichotomy on a daily basis at work. If you actually take the step of trying to make/do/understand something, you’ll quickly realize how little you really know.

If you read my last post about creating a VLAN you may be under the impression that it went swimmingly and I’ve been using my new VLAN whilst sipping on cocktails all the day long. Unfortunately that is not the case. Knowing about VLANs != knowing how to build one. Let me take a moment to give a post-mortem of my efforts.

My first assumption about constructing a VLAN with just a switch and 2 routers was misguided in the context of my original topology. It took some troubleshooting but I came to realize that Modem -> Switch -> (2) Routers still only gives you 1 internal LAN IP from the Modem. For there to be two subnets I need a router to do NAT and potentially DHCP.

Secondly, I did not understand the relatively new technology space surrounding the awesome DD-WRT firmware for routers. I took a trip to Starbucks with my new Cisco router with the idea that in 30 or so minutes I’d have new firmware on the device. After reading the infamous “peacock” thread on the forums, I walked home and put my reading glasses on. Assumption = ass out of me and… me.

After I finally flashed the router, I found it difficult to find the proper configuration settings online. Most technologies have forums upon forums of examples and tutorials, so it isn’t too difficult to find something just like what you need. I thought I found that in this case, but I was again mistaken. I configured my VLAN according to some forum that was *kind of like what I needed. Being slightly hung over and groggy, I copy/pasted away and ended up disabling half of the ports on the router.

A hard reset later left me with a clean slate. Unfortunately the router decided to run at 100% CPU while I was gone, causing the router to crash. My neighbor needing internet took it out of the mix and plugged directly into the modem himself. Understandable move, this process has not been without it’s hiccups.

Now I’m left with a switch, a router and a list of known unknowns to read about. My plan is to hit the reset button on this whole project and figure this thing out once and for all.

The moral of the story is just because you read it in a book, doesn’t mean you can ‘just do it’ even if you are technically savvy. Practice begets experience, and experience is worth more than words in a book/forum/blog saying something is possible, make it a reality and live in that world.

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