The Network Simulator w/ Designer (NetSim w/ Visualizer) provides a virtual lab
environment where a router/switch network can be simulated. The
software is primarily intended for candidates preparing for CCENT,
CCNA, or ICND2 exams though it can be used by any individual desirous
of learning networking using Cisco routers and switches.
Important features of the NetSim software:
Several lab exercises with scenario
type labs have been provided for hands-on practice.
Router and switch IOS simulator for
ease of learning Cisco router/switch commands.