After installing the GNS3 network simulator, the first thing you do is to copy a Router or Switch IOS image. If you don’t have IOS images, you can download the related files here.
How to Add Cisco Router to GNS3
With GNS3 (Graphical Network Simulator-3), you can prepare for Cisco exams more extensively.
You can install this simulator software on Windows, Linux, and macOS operating systems.
You can make more professional network designs by using the images of real Cisco network devices on GNS3.
Now let’s examine how to install and run a router IOS image to GNS3.
After installing GNS3, run the program and select Run only legacy IOS on my computer in the Setup Wizard window.
If you select the above option, you need to install the GNS3 VM.
After selecting Run only legacy IOS on my computer, click the Next button.
Leave the default settings in the Local Server Configuration window and click Next.
In the Summary window, click Finish.
Type the project name and click OK.
In the New appliance template window, select Add an Router using a real IOS image (supported by Dynamips).
Click OK to continue adding the image.
Click Browse to specify the location of the image file.
Select the Router image that you downloaded to your computer and click the Open button.
Click the Yes button to extract the compressed GNS3 Cisco IOS image.
Wait while the router image is decompressing.
After adding Router, click Next to continue.
After configuring the name and platform of the version of the Cisco Router you added, click Next.
Configure a RAM value on GNS3 according to your computer’s hardware specifications so that the Router can perform more efficiently and click Next.
In the Network Adapters window, you can select which slots you want to add to the Router.
To add the FastEthernet interface to the Router 7200 as shown in the following image, select C7200-IO-FE in Slot0 and click Next.
You must specify an Idle-PC value for the router. This value may vary depending on the performance of your computer.
Click the Idle-PC Finder button to set an appropriate value for the Router 7200.
Wait while setting the Idle-PC value.
Once the optimal value found, click OK to continue.
After specifying an Idle-PC value for your router, click Finish.
After you have successfully configured the router, click OK in the IOS Router Templates window.
Drag and drop the Cisco Router that you added from Devices / Router to the workspace.
Right-click on the router to start it.
You can check that the Router is not working at the Topology Summary.
Now, click Start to run the Router.
When the router is running, the Red icon in Topology Summary will be Green. You can open the CLI command prompt by double-clicking on it to configure the router.
As you can see in the image below, the Router you added on GNS3 works successfully!
For example, you can check the running configuration file of the Cisco Router using the R1# show running-config command.
How to Add the Cisco Router to the Physical Network
You must configure a Cloud connection to add the Cisco Router to the physical network to which your desktop or laptop computer is connected.
You can also use this method to take the Router to the Internet.
To configure the router’s FastEthernet interface, double-click on it and open the CLI prompt, and then perform the following commands.
The important point here is to give an IP address to the FastEthernet interface from your physical network.
R1# conf t
R1(config)# interface fastethernet 0/0
R1(config-if)# ip address 192.168.1.100 255.255.255.0
R1(config-if)# no shutdown
Now add one Cloud to the GNS3 workspace.
Right-click on Cloud1.
In the Cloud setup menu that opens, you need to select which network card your computer accesses to your physical network.
Select Wi-Fi, Ethernet, or VMnet Adapter.
Connect one end of the cable to Cloud1/Wi-Fi and the other end to the FastEthernet0/0 interface you have configured.
Click the Start/Resume all devices button to start the Cloud1 and Router.
After you have added the router to the physical network, Ping the computer to test the network connection. You can see the GNS3 Router can communicate with the physical network from the image below.
How to Run a Cisco Router in GNS3 ⇒ Video
You can watch the video below to upload Cisco IOS to GNS3, and you can also subscribe to our YouTube channel to support us!
In this article, we have examined how to configure Cisco IOS to the most popular network simulator program used to prepare for the Cisco exams. Thanks for following us!
♦ Cisco Router Modes
♦ Cisco Router IP
♦ Cisco Router Hostname
♦ Router IOS Images
♦ How to Configure Cisco Router