GNS3 is an excellent platform for simulating a good sized router environment for testing and more importantly for preparing for your CCIE lab. There are, however, some known limitations. The Dynamips software does not currently support more up to date switches like the 3560s used in version 4 of the CCIE Routing and Switching lab. In GNS3 on Ubuntu, you were provided with guidance on setting up GNS3 on Ubuntu GNU/Linux. You were shown how to run it as root and also introduced to the .net file that ultimately drives your lab topology. Dynamips and GNS3 (for the purpose of this article we will refer to it simply as GNS3) both support extending your virtual topology to your physical Ubuntu host. This gives us some very creative options for merging our virtual topology with physical hardware. We will use this article to demonstrate one of two different ways to extend your virtual topology to your physical hardware via some simple .net file adjustments and network configurations. You should already have a reasonable understanding of the fundamentals of Dynamips, GNS3, and the .net files before going too deep into this. You also are expected to have a reasonable knowledge of GNU/Linux and of course Cisco switching. Remember. Google is your friend.