How to configure IOU in GNS3 for real Cisco Switching Labs

Use .ova for GNS3-IOU instead of pre configured VM.

We all may have heard the saying GNS3 is great for practicing routing labs but switching Nah Nah!! Don’t underestimate the power of GNS3. It has a special IOU feature which will let you emulate real Cisco Switch both L2 & L3 in GNS3 without any trouble.

If you want to know what is an IOU? Refer to this excellent article here else follow along…

To configure IOU in GNS3 you will need the following files:

  • GNS3 (I used v1.2.3)
  • Virtual Box
  • GNS3 IOU VM (or .ova file available on GNS3 Official Site)
  • L2 IOU image
  • L3 IOU image
  • License file

For you to access them easily I am making all the “rare files” available for you here :

Let us now go through the step by step process to configure IOU in GNS3:

  1. Install the GNS3-IOU .ova file in Virtual Box. Make Sure you don’t have any older version of IOU installed in it.
  2. Start the VM. It may take a few moments to run at the first time.
  3. After it has started, you will note an IP address shown above the console screen. In my case it was: where was the IP of the VM which was the Host-Only adapter of the Virtual Box instance.
  4. Next open your web browser and go to
  5. Select the L2 and L3 IOU image one by one and click on the upload button. The full path will be shown after uploading is completed.
  6. Now open GNS3.  Goto edit->preferences.
  7. Click IOS on Unix. Under path to IOURC put D:\GNS3 IOU\IOURC.txt (the location of IOURC.txt file).
  8. Next, goto GNS3 server->Remote server. Under host type – and port 8000. Click Add. Then click Apply->Ok.
  9. Change host binding. (Very important)
  10. Now under IOU devices, Click New->Next->Ok->Give a name(like Switch IOU). Under IOU image paste the location which you have copied from the image upload screen.. Select L2 or L3 depending on the type.
  11. Repeat step 9* for the Router IOU image.
  12. Now simply drag your IOUs to your working area and create your switching lab.

Now let us test inter-vlan routing in this simple topology.


Sample R1 Config:


Sample SW1 Config:


Final Testing:


Cheers ! Happy Switching 😉


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  • Cuong

    Hello. I want to know Password rar files please! Thanks

    • unknown

      try above domain name with .com

      • uday singh

        is it……………… its not working

  • Mike

    What is the password for the RAR file? Thanks.

    • unknown

      try domain name with .com
      worked for me

  • unknown

    Hello Srijit. I followed the steps and getting below error when starting the IOU Switch or Router.

    Server error from IOU1: IOU key not ending with ; in iourc file

    Can you please help. Thank you,

  • nitesh

    Server error from IOU4: IOU key not ending with ; in iourc file
    Server error from IOU1: IOU key not ending with ; in iourc file

    • Just add a ; at the end of the line.. This happened due to GNS3 version upgradation.

  • JacobC

    Yeah I cant get the rar password correct either. I tried a couple of different combos of the domain with .com

  • Theophilus Blaudfaust

    please can somei=one help me with the GNS3 IOU VM_1.3.2 passoword. when i i got a username and passowrd

  • uday singh

    can anyone tell me the password

  • Agam Sethi

    Passwords is

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  • Jagpreet Singh Randhawa

    The above link is not working srijit.
    Can you send me a new link on my email ‘’
    Thanks for such a great blog.

  • Jagpreet Singh Randhawa

    srijit password is not working can you tell me whats the password ?

  • Fatima Ali

    hy can anybody have IOS for 3750 switch.i really need one.

  • Raj

    Hi Sirijit, thanks for the files to configure IOU in GNS3. password is not working. Can you please email me the pwd. Thanks

  • jayraj salunkhe

    what is password for rar file?

  • jayraj salunkhe

    can anyone tell me rar file password.

    • Imtiaz khan

  • Imtiaz khan

    Can someone tell the user name and passowrd for login (not for rarefile , i alreaady passed that point , the passowrd for that is )

  • Sreekumar

    Hi for me Its not working can anyone help me ? i am not able to start the device following error is coming

    => Error while creating project: Client version 1.3.13 differs with server version 1.3.3