How to Connect Cisco IOU to GNS3-1.1 and Emulate Cisco Switch in GNS3-1.1

By | November 2, 2014

Well, what’s up? Today I’m going to discuss an interesting GNS3 Cisco simulator tutorial on how to connect Cisco IOU to GNS3-1.1. This is an alternate way of emulating Cisco switches in GNS3.

So I hope this article will answer how to get a working layer 2 switch in GNS3-1.1

By the way what is a Cisco IOU device? Cisco IOS on UNIX (IOU) is a fully working version of IOS that runs as a user mode UNIX/LINUX platform. IOU is built as an image and runs just like any other program. Layer 2 and layer 3 IOU images are available for switching and routing respectively. Cisco IOS on UNIX is aimed for internal uses only (Cisco employees). Distribution of IOU images to customers or external persons is strictly prohibited.

The new version of GNS3 (1.1) supports IOS on UNIX, thereby providing fantastic Cisco switch simulator to the users. Usually people who are preparing for CCIE Routing and Switching will be using IOS on UNIX facility.


The process to connect Cisco IOU to GNS3-1.1 is a little bit hassle though, but I’m gonna give you simple explanation with step by step procedures.

Tools Required

  1. GNS3-1.1: Download from here
  2. Oracle VirtualBox: Download from here
  3. GNS3 IOU VM.ova: Is the Virtual Unix platform to run IOU image. It is a virtual box OVA file: Download from here
  4. IOU image: IOU image is intended to use only for Cisco employees, distribution of IOU is strictly prohibited. Please don’t ask me! Google is your friend always.
  5. iourc.txt file: Is the license of Cisco IOU image. I have no privilege to provide it publicly, but I found a discussion related to it. It may help you.

Now we are ready to go…

Step 1: GNS3 IOU VM.ova Setup

Double click ‘GNS3 IOU VM.ova’ , it will open up in VirtualBox (if you have installed VMware please right click on the GNS3 IOU VM.ova file and change the ‘open with’ to Oracle VM VirtualBox).

Click Import button, it will be imported to VirtualBox VM list.
Go to Settings → Network → Adapter 1
Make sure it is attached to Host-only Adapter with name VirtualBox Host-Only Ethernet Adapter. Then click OK.

Start the GNS3 IOU VM, then login with following credentials.

User name: root
Password: cisco

Step 2: Upload IOU Image to Unix (GNS3 IOU VM)

Check the IP address of the GNS3 IOU VM by ifconfig command and note down the IP (my case
Now come to the host machine and open any browser (I’m a Chrome fan). Enter the following link in the address bar

Choose your IOU image and click Upload button.
[Note: the location of the file being copied (/home/gns3/GNS3/images/XXXXXXXXXXXXXXXXXXX)]

Now our IOU device is ready to run….!

[Troubleshoot: Please allow 192.168.56.XX network in the firewall, Disable proxy if you are using. In local PC (host machine) be sure that your VirtualBox Host-Only Ethernet Adapter is set to accept DHCP]

Step 3: GNS3 Server Configuration

By default GNS3 host binding is (local host loopback) address, we have to change the server to 192.168.56.XX:8000.

Go to Edit → Preferences → GNS3 Server → Local Server
Drop down the Host Binding section and choose 192.168.56.XX, local VirtualBox Host-Only Adapter IP (mine and click Apply.
Again Edit → Preferences → GNS3 Server → Remote Server
Add a host by entering UNIX GNS3 IOU VM IP address that we noted in Step 2 (mine and 8000 as port.

Step 4: Connect Cisco IOU to GNS3-1.1

Go to Edit → Preferences → IOS on UNIX → General Settings
The set the path of iourc.txt (iourc.txt can be stored on any directory of your local PC, eg: Desktop), browse and select it.
Now go to IOU Devices, click New button and select server type as Remote. Your remote server will be listed there → Next
You will receive a message “You have chosen to use a remote server, please provide the path to IOU image located on the server!”, just click OK.
Now type a Name for the IOU image and set IOU image path that you noted already in Step 2.
Type should be L2 for switch IOU.
Click Finish button. That’s that!
You have success fully configured Layer 2 Switch in GNS3-1.1…! Go to GNS3 GUI and drag the switch in to work space.



Now explore your new GNS3 Switch!

Hope I explained each steps to get a working IOU in GNS3-1.1
This will be very useful for CCIE training and if you like the post please share and support us.

21 thoughts on “How to Connect Cisco IOU to GNS3-1.1 and Emulate Cisco Switch in GNS3-1.1

  1. Alex Deen

    I have done all the steps but the switch isn’t turning on… Also on GNS3 Server the “host binding” ip address doesn’t match that of the ip address of where switch images were loaded. Dunno if that matters or is related or not but It only provides the address

    1. Admin Post author

      Hi Felix liu,
      First go to the directory where the images located
      root@gns3-iouvm:~#cd /home/gns3/GNS3/images

      Then use ‘rm’ command to remove files from there
      root@gns3-iouvm:/home/gns3/GNS3/images# rm FILE_NAME


  2. Rajesh Thapliyal

    I m getting below types of error.what does this means
    Server error [-3200] from IOU1: IOU image ‘C:\Users\manish\Desktop\songs\ios\C7200.AD’ is not accessible
    Server error [-3200] from IOU1: IOU image ‘C:\Users\manish\Desktop\songs\ios\C7200.AD’ is not accessible
    Server error [-3200] from IOU2: IOU image ‘C:\Users\manish\Desktop\songs\ios\C3725-AD (1).BIN’ is not accessible
    Server error [-3200] from IOU1: IOU image ‘C:\Users\manish\Desktop\songs\ios\C3725-AD (1).BIN’ is not accessible

    1. Ron

      Hi Rajesh,

      When you paste the address

      From your VM #ifconfig–Check the IP and put in below place of x.x.x.x

      The output of abvove shows the location of files. Just copy paste and add them as the location.


  3. ms

    i got error

    could not connect to on port :8000 timed out

    what to do please

    1. ajmal

      i done with all step but when i drag and drop node it doesn’t work and when i point out the node with mouse it shown error message (this node isn’t initialized unknown error)

  4. vladdar

    HI, I can’t upload my image IOU_v22_UD-disk1 in step 2 and I don’t know why, I am able to upload other files. Maybe it is too big? approx. 900M
    I can see webpage connection tinterupted when I try to upload it.

  5. Kogee

    I keep getting the following error message at GNS3

    ” Could not connect to on port 8000:[WinError 10061]. No connection could be made because the target machine actively refused it”

  6. Kogee

    The other error at GNS3 console;

    => Server error from IOU1: IOU image ‘/home/gns3/GNS3/images/IOU/Cisco_IOU_L2_L3_Collection_v2.7zRep_….exe

    ‘ is not accessible

  7. jai

    GNS3 console error message;
    Server error from IOU1: ‘/home/gns3/GNS3/images/IOU/i86bi_linux_l2-ipbasek9-ms.may8-2013-team_track’ is not a valid IOU image

  8. Dennix

    A well written post. Worked like a charm. Any pointers on how to connect iou devices to the host PC. I ve tried the cloud device but it kept saying that “the device (cloud) shoulld be connected to a device (router) on same host”

  9. Alberto

    Im getting the Server [-3200] message as well. IOU image is not accessible.

  10. MK

    I had tried the steps on GNS 1.3.1 and 1.3.7, but it didn’t work as the GNS3 was throwing some errors that client (i.e. 1.3.1) and server (i.e. 1.3.3) version differs when i was adding the switch to the topology.

    However, i don’t see the issue when running 1.3.3 version.
    May be somoneone can please confirm.

  11. wahid


    All seem to work but when I drag a L2 or L3 deice in Gn3 to configure, it has a red S over it and it reads THIS NODE ISN’T INITIALIZED, UNKNOWN ERROR.

    I spent almost full day trouble shooting it, could not succede.

    Can you help 🙂


  12. chris

    is there a way to get rid of the default device names IOU1 IOU2 en replace it with R1 R2 etc

  13. balvinder

    i follow ur step and iou is working but i want to use two iou layer 3 device. could i use by using a single virtual machine.
    i did like this but hsrp is nor working properly. both the layer 3 devices are showing active is local router no standby. help me to solve this

  14. Abhishek kapil

    Hi All,

    Gud evening.

    I have followed all steps for installation and when i am dragging any L2 and L3 switches then “this node isn’t initialized” error is appearing on screen.

    i am using latest version of GN3.

    is this a version problem or anything else.

    thanks in advance


    Can someone please resolving this problem. Did anyone found a solution for the IOU devices that has the red S on them, mean they are not initialized despite all the steps are followed properly…?



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