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How to Install a Cisco (IOS) Router On GNS3 VM

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By: Parvez Ahmed

July 24, 2017

The blog is for the users who would like to simulate the router environment in GNS3VM irrespective of the vendors (Cisco, Juniper etc.) In my earlier blog, I explained how to install and configure the GNS3 VM and how to configure a device through a template (from GNS3 Marketplace).

Today, we'll install a device on GNS3 VM that is not available in GNS3 Marketplace (CISCO IOS). Gns3 has a feature called Dynamips which allows us to install (CISCO IOS) image and emulate the router environment. To perform router installation, we need to have an IOS image.

Let’s install router C-3640 on gns3 now.

  • Step 1: Open the gns3 VM then navigate to -> Edit->preferences -> Dynamips -> IOS routers
  • Step 2: Now click on new and select option “Run IOS Router in GNS3 VM” and press NEXT

Note: There is another option “Run IOS Router on Local Machine” this option was used before the introduction of “GNS3 VM” however, we have GNS3 VM so we will go with the latest option to achieve good performance and emulation.

  • Step 3: Now import the image of the router you would like to install on gns3 VM by clicking on option browse then say YES to “decompress” the image.
  • Step 4: After image gets uploaded in next window “Assign” a name to the device then platform and chassis type.

Note: Cisco 3600 has three distinct models and different chassis for all the models, If you want to make this router function as an L3 device (i.e., Switch + Router) then check option “This is an ether switch router” and click on next.

  • Step 5: Now assign the amount memory (RAM) to this device and press next, 256MB memory would be enough for simple operations.
  • Step 6: Next menu will ask you to select the number of “Network adapter” you would like to have on this router for every running instance of this router then press next.

Note: You can run any number of instances of a single router installed on gns3.

  • Step 7: Now select the idle PC value, just click on “idle PC-finder” button to allow gns3 to input the value automatically.

Note: Idle-PC value is used for preventing the device from utilizing 100% CPU.

  • Step 8: Click on Finish to complete the installation, then click on apply and ok buttons to close the “Dynamips” window

Making use of the device we have installed i.e., Router-3640.

In gns3 GUI application windows click on browse all device menu button it would look like this.

Then select the router and drag it workspace area, now click on run button or navigate to -> Control menu and click start/resume all the devices option to run the device.

Opening Console:

Right click on the device, then select "CONSOLE" option a window will appear where you can configure the device with as per your wish.

Here you can input/enter all the IOS commands to configure the device.

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