Network Simulators

GNS3 – This is an excellent free hardware platform emulator. If you have access to Cisco device firmware, then GNS3 is a great, inexpensive option for configuring an anytime/anywhere virtual network training environment on your laptop. GNS3 supports Cisco 1700 series, Cisco 2600 series, Cisco 3600 series, Cisco 3700 series, Cisco PIX and ASA firewalls, and Cisco IDS sensor firmware. Cisco 7206 routers. Unfortunately, GNS3 does not support Cisco Catalyst switches (due to firmware ASIC requirements).