Still adding more tools daily. Chill out.
Network Emulation Programs
-GNS3 (Switching functionality following the 1.0 release is limited to IOU files, very basic support prior to 1.0 [switchport module on routers])
-Cisco VIRL (Cisco’s new GNS3 “Killer”. Unfortunately they charge a pretty penny and it’s yearly. They do have some neat real time visuals)
Network Simulation Programs (Simulated IOS, not full capabilities)
-Packet Tracer (Tried and true, Cisco’s own invention. This little guy doesn’t have the full range of commands or abilities and is strictly a simulator. Link unavailable, as this one requires a Cisco NetAcad account to download. Search cisco.com to find it)
Free Software for Network Management and Troubleshooting
Spiceworks – http://www.spiceworks.com/ – Free network monitoring solution packed full of features including live monitoring, dashboard display, email notifications, a built in help desk ticketing system, and more. For a network admin baller on a budget, this tool is a good roundup for monitoring overall IT health.
Nagios – http://www.nagios.org/ – A bit more complex with regards to setup and configuration, Nagios is tried and true open source monitoring. As with much open source software, it is also community driven through add-ons and configurations other users post.
Observium – http://www.observium.org/wiki/Main_Page – Rocking some small rodent with spy gear for it’s brand, this odd contribution to network monitoring describes itself as an auto discovering network monitoring platform. Based on the online demo, this appears to be a clean and intuitive management system for network and system devices. Keeping track of metrics with regards to processor usage as well as traffic throughput, graphs are easily identifiable per device.