Good Gear Guide
Seven secret weapons for network management on a b...
Many network administrators do not have access to a suitable lab that really mimics the production network. However, it is often useful to configure a simple little scenario to validate an idea or prototype a solution. Dynamips is a system that allows you to emulate Cisco IOS image files and run them in a configurable environment. You can use Dynagen 1.11.7 or Graphical Network Simulator (GNS3) 0.7.2 front-ends that utilize Dynamips underlying capabilities to make it easy to configure a virtual lab of Cisco routers joined together.
Seven secret weapons for network management on a budget