Graphical Network Simulator 3

Graphical Network Simulator 3

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This simulator is absolutely awesome. It requires that you have the Cisco IOS images as it comes with a MIPS emulator and actually emulates a real Cisco router, switch, or PIX firewall. It's so realistic that you can design a network, configure the routers and switches, and then drop the running configurations onto real network gear.

It certainly helps to have plenty of RAM available to run this. 1 GB or more is almost a necessity.
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