For anyone who has ever needed to test a new network architecture, implement a new routing protocol or simply study for a Cisco exam has needed access to a real live router or a router simulator. But buying a bunch of routers just test up an idea or for study is expensive. And until recently good fully functional router simulators we just something we could only dream about.
Some company’s, like Boson have router simulators you could buy to help you study for the CCNA but it was extremely limited with limited functionality. There was also some open source software like dynmips and the hypervisor engine that could be used to simulate a router but these applications were really difficult to configure and only support limited models.
Well now there is GNS3 – a multiplatform Graphical Network Simulator. GNS3 builds on dynamips and dynagen to create a nice graphical front end for building complex Cisco networks. I was completely amazed at how easy it was to install and build a new network, configure routers and switches and have a nice simulated network up and running.
GNS3 is a free open source router emulation software application developed in Python and uses the PyQT libraries for creating the UI. It uses standard vector graphics similar to Visio to create the network digrams and layouts. GNS3 uses real Cisco IOS for creating fully function emulated routers and switches.
GNS3 supports many types of interface configurations (pretty much if its in the IOS its supported). Frame Relay, Frame Relays Switches, ATM, Ethernet, OSPF, EIGRP, BGP, and more.
The only draw back that I can say so far with GNS3 is that you need a pretty hefty machine to simulate a large network. Especially if you are trying to build it on a Windows machine. I havent tried but I have heard that runing GNS3 on linux is much more manageable.
Another application that has similar functionality is Cisco’s Packet Tracer. Though originally designed as a group learning tool for Cisco Academy students, it makes for a nice router simulator. And because its built for Cisco Academy, the only place to get it is if you’re enrolled in Cisco Academy. Another problem with Packet Tracer is that it only runs on Windows. It’s a bit more limited than GNS3, as it comes preconfigured with set models of routers and switches. It is very stable and less resource intensive than GNS3 by a long shot and will do the trick when you need to test out a quick config. To find Packet Tracer is pretty easy if you look out on the bit torrents, you should easily be able to find it.
So if your looking for a cool router simluator and have been frustrated thinking they dont exist. Think again! Here are two really cool simulators right here!
One Final note – there is a great site for sharing lab related configurations and topologies using GNS3 – GNS3 Labs