I learned of a very unique and amazing program a couple of weeks ago. Ever since my discovery, I have found it very useful in my day to day work.

The software I'm speaking of is an emulator, but not your common pc or mac emulator. No, this is not another game platform emulator - (I did say useful in my work).

This program emulates a Cisco 7200 router! If you have ever seen router simulators for test study purposes, you know that they try to be as close to the real thing as possible.

With dynamips the hardware is emulated that of a Cisco 7200, similar to an Intel PC emulator such as VMWare. This means that you need a valid operating system in conjunction with the emulator. So, the same image used on your 7200 router is also used with dynamips.

You can obtain a valid image from the cisco.com website, provided you have a support contract of any kind. I have successfully booted anything from 12.2 IP only images to 12.4 Enterprise software. Once booted, you basically have a usable 7200 router completely made up of software.

The emulator can be configured with different hardware components, such as: Serial, ATM, Ethernet Cards, flash cards, and more. More than one emulator can be configured and booted at the same time. Things like frame relay, ATM, and virtual Ethernet switches can also be configured so that the virtual machines can talk to each other over these mediums. One more exciting little piece: an Ethernet port on a virtual router can be mapped to your pc's Ethernet card! Now your emulated 7200's have access to THE real network your pc is connected to.

This brings all sorts of possibilities: Your virtual routers can participate with other existing routers in your network! How cool is that!

Although one might see this as an opportunity to use this software on a pc in place of a real hardware router - make no mistake, this program is targeted to promote learning only and certainly not any type of production work.

Now for the 'other' details:

This software is very cryptic to configure! Thankfully, there is a separate project that's focus is to make the emulator configuration much more user friendly.

The dyna-gen project uses a plain text configuration file to configure your total environment. Once you have your environment setup with any number of routers, interfaces, virtual switches, etc. - it is easy to go back the next time and work with the same scenario.

If you install dyna-gen, it includes everything you need (minus ios image). It will probably include a version of dynamips that is a revision or two behind. If you want to run the latest, you should just be able to download the latest dynamips from here and simply replace the exe contained in the dyna-gen installation. However, by doing this - any new feature or optimization in dynamips wouldn't necessarily be available when running through dyna-gen. This is simply because dyna-gen is a 'wrapper' to go around dynaips. Clear as mud?, I thought so…

Seriously, you will definitely see this useful if you work on routers at all. Let me know what you would like to see and I'll help out where I can… For example, pre-built configuration files ready to run in dyna-gen that already has a particular network setup.

At the dyna-gen site, there are sample networks and instructions on how to build.