GNS3 is a graphical network simulator that allows simulation of complex networks.

To allow complete simulations, GNS3 is strongly linked with:

• Dynamips, the core program that allows Cisco IOS emulation
• Dynagen, a text-based front-end for Dynamips
• Qemu, a generic and open source machine emulator and virtualizer
• GNS3 is an excellent complementary tool to real labs for network engineers, administrators and people wanting to pass certifications such as CCNA, CCNP, CCIP, CCIE, JNCIA, JNCIS, JNCIE

Features:

• Design of high quality and complex network topologies
• Emulation of many Cisco IOS router platforms, IPS, PIX and ASA firewalls, JunOS
• Simulation of simple Ethernet, ATM and Frame Relay switches
• Connection of the simulated network to the real world!
• Packet capture using Wireshark
• Important notice: users have to provide their own IOS/IPS/PIX/ASA/JunOS to use with GNS3