Routers, and Switches, and Labs - Oh My!

Well, finally got my "lab" up and running.

My lab consists of two servers and one desktop, all running Dynamips. If you don't know what Dynamips is, it is a Cisco Router emulator. Now, this isn't your Boson or other lab sim as Dynamips actually runs real IOS images and best of all - it's free! Also checkout Dynagen which is a nice front-end to Dynamips.

You may be asking - why servers? Well, it got them for a great price from Geeks.com. Each one costed me $130. The include dual AMD 2.0Ghz+ dual-core processors with 4 GB of RAM. The only down side to these servers is they do not include any Floppy or Disc drives. So to install CentOS, I simply plugged a DVD drive into one of my many USB/IDE external adapters. I was then able to boot up the CentOS 5.1 DVD and install CentOS onto the 80GB IDE drive. One other great thing about these servers, they are IPMI capable. What this means is I can remotely turn them off and on from anywhere in the world. Seeing as these things are pretty loud, my wife appreciates this and I appreciate the reduced electric bill when I am not using them. The desktop machine is actually my old desktop machine with an old AMD 2Ghz processor with 4Gb or SDRAM. Check out the pictures of my lab.

To equalize the load, the two servers and the desktop all run their own separate IOS instances. Dynamips is running over a base CentOS 5.1 installation. If you are going to use Dynamips, I highly suggest using Linux. With linux, you will have more available resources to dedicate to your router/switch instances as opposed to Windows. If you are new to Linux, it's still pretty easy to get CentOS 5.1 up and running and getting Dynagen/Dynamips installed. Some people have had success running all 15 router instances on their personal desktop. This may work, but I did not want to bog down my desktop and in keeping the instances spread out, I achieve almost real-life responsiveness from my routers.

As I mentioned before, I am using the Internetwork Experts Dynamips Lab Workbook version 4.1. I had to adjust the dynagen .net configuration file so that I could spread out the router instaces, but outside of that, everything is running great. The one thing I couldn't get working was the Terminal Server. I couldn't quite figure out how to add another loopback or tap interface to CentOS. Seeing that I am using SecureCRT, this was not a huge deal to me. I just save all my router sessions in SecureCRT to a folder, and load them up all at once. I know how to use a terminal server, but it was not critical to my success in practicing for the lab.

That's all for now. I've actually started into the first lab exercise and I've already run into some problems. More on that later.