If you are a Cisco guy you should probably know about GNS3 and Dynamix, they allow you to emulate Cisco switches and routers in your Linux or Windows box, rumor has it, that a OpenSolaris port is in process. It truly is awesome to have a Cisco 7200 class router on your desktop to play with,  you shouldn?t use it as a production router but it?s a good way to get ready for your CCNA or CCIE tests and get experience with Cisco routers.

One of the reasons I got the ESXi box was so that I can play with it, without adding yet more ram hogs to my desktop system, just a note, GNS/Dynamix don?t play well with  64bit Vista. It?s much nicer on Linux.

Ubuntu has GNS3 package available just install it. And add the IOS images of your choice. Now one issue I did come across with it is that you have to enable promiscuous mode on the virtual switch or you get a really crazy results, the traffic from your router makes it to the outside world, but your router can?t see any traffic, it looks like a firewall so you get to try and found the firewall.

You need to run ?IDLE PC? test to limit the CPU usage on the system, as well as install VMware tools to get the benefits of ESX?s memory management.