GNS3 On Ubuntu 11.04 | The Ultimate Cisco Emulator 8 comments

GNS3 is a graphical network simulator that allows simulation of complex networks precisely but not limited to Cisco.GNS3 uses Dynamips for emulating Cisco’s IOS and is quite similar with Cisco’s IOU i.e IOS on Unix (IOU) a fully working version of IOS that runs as a user mode UNIX.Problem is that we cannot use IOU in legal way since its usage is limited to Cisco only and not to mention even the discussion is prohibited.But to our rescue is GNS3 which does effectively what IOU is supposed to do.


About Dynamips

Dynamips emulates Cisco 7200/3600/3725/3745/2600/1700 Routers on a traditional
PC.  You can use dynamips to create labs. It uses IOS Images (which are not
part of this package). Of course, this emulator cannot replace a real router.
It is simply a complementary tool to real labs for administrators of Cisco
networks or people wanting to pass their CCNA/CCNP/CCIE exams. For a Command
Line Interface for dynamips see dynagen or gns3 package.


Installing GNS3 is Ubuntu is very easy since it is already available in repositories.Just open up the Ubuntu Software Center and search for GNS3 or you can just popup your terminal and type

sudo apt-get install gns3 dynamips

Remember that you need to have your own IOS files to run it on GNS3.


Done with the install now lets move on to the configuration part.

  • Go to Edit > IOS Images and Hypervisor and add the IOS image you’ve got.
  • Save the settings and move back to the topology map.
  • Add the device by just dragging and dropping
  • You may also consider changing the Idle PC value to one marked with * after you add a device since this will make your system more stable by consuming less RAM
  • Select the device and click start button on the top and then click Console

That’s it for now ..Do visit the GNS Homepage in case you wanna thanx and Happy “conf t”

Any queries regarding Ubuntu/Mint or any other regarding linux can be asked at the forums freely.

Here are few screenshots after installation

About Gaurav Saini

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  • Manickam

    Thats good to know everything above. But having issues with opening the console windows for the routers. Could you pls share the details? I use GNOME Terminal. But it is not getting liked with the router console.

  • You can always have other terminal emulator like putty that are cross platform ..Also may like to visit the GNS3 website ..there is a link there you might get help with 🙂
    Hope this will be helpful…do reply if you are still unable to get result

  • Manickam

    Yeah… Thanks for the help. Actually the IOS had the problems loading with the GNS3 through the console. Now things are fine with different image. Thanks for the reply.

  • Saburiparvatkar

    can gns3 be used to simulate wireless sensor network?…and is there a power module function in gns3 to simulate energy efficient MAC protocols?

  • GNS3 is Cisco specific only extended to some Juniper devices too . Don’t think it will simulate what u want.rather u should look at ns2

  • Swati114

    can you plz elaborate on the differences between ns2 and gns3

    Thank You….:)

  • Jah mon

    I am getting srial s/01 up but line protocol down what can I try to to get line protocol up.

  • Jah mon

    I am using linux ubuntu 11.10