Connecting GNS3 to Real Networks: Physical Networking with GNS3

By | June 12, 2014

GNS3 (Graphical Network Simulator), best network simulation software allows you to connect and collaborate virtual network topologies to real networks. This awesome feature of GNS3 brings CCNA, CCNP and CCIE labs with zero Hardware! Personally I was much excited when came to know this possibility in GNS3. You might even associate to virtual machines from VMware or VirtualBox to this powerful piece of software. In this GNS3 guide I’m gonna to share connecting GNS3 to real networks. I already shared one article of GNS3 in that we discussed about calculating Idle PC value in GNS3 running over Windows platform. Linking a virtual topology in GNS3 to real devices is very exciting and interesting and which makes business network setup well..

Now let me get in to the technical description of virtual network lab.

Tools required

  • GNS3 (Graphical Network Simulator): It is the best network simulator software that is offered for Windows, Linux and MAC. There are many network simulation tools are present like Packet tracer (best CCNA simulator, this will be very useful for CCNA practice test for people who learning CCNA routing), BOSON Netsim etc. The specialties of GNS3 is that it is FREE and we may run real Cisco IOS image in GNS3 router hence you may have realistic experience!

GNS3 network simulation software free download

  • Cisco IOS: Real Cisco IOS is required for running GNS3 labs. Distributing Cisco IOS without license is illegal so you may please Google for IOS.

How to interface or connect GNS3 to real networks?

There are three topologies that we can realize with real networks together with GNS3.
1. Connecting GNS3 topology to Host computer.
With the help of a ‘Microsoft Loop-back adapter’ we can connect GNS3 router to our Host PC

2. Interfacing VirtualBox virtual PCs with GNS3.
GNS3 supports VirtulBox interfacing. Possible to connect GNS3 router to VirtualBox PCs
(I will post on next article)

3. Connecting GNS3 to Internet
Wow! Just amazing! You may possible to implement VPN with this feature. Keep in touch with me, I will be coming with those guides soon.
As we are starting Real network interfacing I explained the first option in this article (Connecting GNS3 topology to Host computer). I will be posting other two options as soon as possible.

Interfacing GNS3 network to Host computer

The process can be explained with in 3 stages viz creating PC LoopBack network Adapter, Assigning IP Address and Connecting GNS3 virtual network to PC LoopBack Adapter. [My platform is Windows 7]

Stage 1: Creating PC LoopBack network Adapter

For interfacing GNS3 network we should have a dedicated network adapter, don’t worry we can create a Virtual LoopBack adapter in Windows 7, which serves as Physical connection.

Step 1:
Right click on My Computer → Properties → Device Manager

Step 2:
Right click on the first icon (computer name) then select Add legacy hardware

Step 3:
Add Hardware Wizard will appear. This will let you to install driver software for LoopBack adapter. Just click Next

Step 4:
Choose manual installation and click Next.

Step 5:
You will see a list of hardware here, look for Network Adapters, and then click Next

Step 6:
In Select Microsoft Adapter window select Microsoft Loopback Adapter, → Next.

Step 7:
Now you are ready to install Microsoft Loopback Adapter, click Next to begin installation.

Complete the installation by clicking Finish button.

Stage 2: Configuring Loopback Adapter and Setting up Static IP

Step 1:
Open Networking and Sharing Center by right clicking in the system tray bar icon.

Step 2:
Click Change Adapter settings.


Here you may find the newly added Microsoft Loopback Adapter. For easy identification I just renamed it in to LoopBack

Step 3:
Right click on the Loopback adapter and take Properties, then double click Internet Protocol Version 4 (TCP/IPV4)


Step 4:
Enable the radio button ‘Use the following IP address’ and enter any IP as you like; I used Class A IP with default subnet mask

Stage 3: Connecting GNS3 virtual network to PC LoopBack Adapter

Now we are gonna to enter to the real meaning of this article, we completed all prerequisites for Interfacing GNS3 with Host computer.

Step 1:
Run GNS3 and add a Router topology to the working area. (I hope you know configuring IOS image for GNS3)
Go to ‘Browse all devices’ then drag a Cloud to the work space area.

Step 2:
Right click on the Cloud and Configure.

Step 3:
Click C1 node, in the NIO Ethernet tab identify and select the loopback adapter that you created just before. (You may find all the network adapters that is present in your PC, but select only Loopback adapter.)

Click Add button to complete.

Step 3:
Interconnect between your Router and the Cloud with Fast Ethernet cable.
Now Run the topology


Step 4:
Console your router by right clicking on the router icon.

Step 5:
Configure your router to assign an IP address for FastEthernet 0/0 interface. Configuration commands are followed. (The IP address must be in the same range of Loopback IP and subnet, for me, assigned with subnet)

Connected to Dynamips VM "R1" (ID 0, type c2600) - Console port
Press ENTER to get the prompt.

R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#interface fastEthernet 0/0
R1(config-if)#ip address
R1(config-if)#no shutdown

That’s all, you have done it!

Now try to ping from Router console window to the Host computer and vise versa.
Pinging from router to Host PC

Pinging from Host PC to Router

Wow, it is pinging in both directions.!

Is this GNS3 guide helped you? Can I have your feedback please? Share your thoughts using the comment box below.

***   ***   ***

Bonus Tip: You can change the cloud icon for better representation, for that
Right click on the Cloud icon → Change Symbol

Choose Computer icon from the list.

Now you will have better diagram representation

***   ***   ***

In my next article I will be teaching you Interfacing VirtualBox virtual PCs with GNS3. Till then check out some of my Cisco articles. Don’t forget to like our Facebook page to get latest updates.

35 thoughts on “Connecting GNS3 to Real Networks: Physical Networking with GNS3

  1. Daniel Jose Cubero Muñoz

    When i use cloud with router on gns3 i have to desactive my firewall of windows 7, It´s a possible tell the firewall allow loopback conextion without desactive. How i do that?

    1. Admin Post author

      Hi Dani,
      You can define custom Firewall rules from the Advanced Firewall settings.


    1. Admin Post author

      Hi Nounou,
      Glad to know that it was helpful. We’ll be coming up with more GNS3 networking tutorials, stay tuned.

  2. timaz

    thanks for your post. it is good to mention that in some cases connecting cloud to the vRouter on GNS might face with some errors like “Server error [-3200] from R1: unable to create generic ethernet NIO” or something like that. in that case, you can restart your machine and the error will disappear.

    1. Yasir Saad

      In fact, I had this error, and I realized that GNS3 must be started as ‘administrator’ for this feature to work. That’s the trick for it.

  3. Nsiko Samuel

    I have tried this configuration in GNS3 but for some reason the router is not able to ping the cloud and yet I finished connecting the cloud with ip address but can ping the network address which is on which the cloud is directly connected.

    configure terminal
    router rip
    configure terminal
    interface FastEthernet0/0
    ip address
    no shutdown
    interface FastEthernet0/1
    ip address
    no shutdown
    configure terminal
    ip dhcp excluded-address
    ip dhcp pool cyber

    1. Nsiko Samuel

      The host ip can ping the router on but the router cannot ping the host

      1. Ashish Thakur

        I have followed your steps however i can ping from my cmd to router but cannot do the reverse why so as per your instruction you have done that

  4. seddeeq

    good morning sir. how are you? i m a student of ccna. my question is why we connect gns3 with real network? and what kind of configuration we can practice after connecting gns3 with real network? please send me

  5. JJohnson

    This process has stopped working for me inside of Windows 8 as of a week ago. I use to be able to create loopback adapters that connected my physical PC/VmWare virtual machines directly to my GNS3 environment without fail until recently in Windows 8 the same way I did in Windows 7 “WITH ZERO PROBLEMS.” “It makes absolutely no sense” why I can no longer do this after a simple “reset” of my PC back to factory default. My firewally is deactivated/diasbled (as always) and I’ve gone a step further by turning of Windows Defender as well, but it’s still not working…

    I’m one step from crying “conspiracy theory” against Microsoft because there’s no explanation for the process to “stop” working, thus now requiring you to “share” or “bridge” your loopback connections with a physical adapter in order to now get your physical PC and/or virtually assigned machines to communicate with your VmWare environment… It’s making me wonder “if” during the reset my PC reached out to microft and upon doing so had a script loaded to it that blocks direct loopack adapter communication between GNS3 and loopback adapters (again, that’s just conspiracy theory, “but” it’s REALLY got me wondering at this point.
    Anbody figure this out minus using “sharing,” “bridging,” and all that over “mess/hoops” you have to jump trough just to make a “simple” connection?


  6. sam

    very helpful. Ok now i connected my Gns3 to internet.
    I was wondering if its possible to create a VPN from GNS3 router to a real real Cisco router over the internet? is it possible ?

  7. umar

    please help !
    i am using window 8 .i install loop back interface but it is not showing in gns3. what i should do

  8. Mateus_CCNA

    Man, it is fcking awsome! I’m studying for CCNA Security and I need to master CCP in GNS3. Your explanation is perfect…

  9. illuminaughty

    Thanks for the tutorial. It got me most of the way but….
    I couldn’t get the above to work. I followed this CBT Nugget video and it works like a champ.
    For some reason ip route fa0/1 wouldn’t work, even though it was the correct interface.
    I changed my default route to: ip route (My SOHO router’s address)
    After that I could ping

    CBT Nugget on GNS3 and getting out to the interbutts:

  10. kamo

    this course is very usefull.
    thank you for your helping

  11. Muhammad

    When i want to connect link between router and cloud it did not work !
    Actually nothing did not appear ??????????
    What should i do ?

  12. Ismaila

    I need help connecting the cloud to the vRouter. I have tried all means known to me and am still gettin same error message – “Server error [-3200] from R1: unable to create generic ethernet NIO”. Thank you.

  13. Mallikarjuna

    After add loopback interface i am not able to git ping from the router ip i hope yet.

  14. surajit

    When i am connecting cloud and router it is throwing some error…….” This device can only be connected to cloud on the same host”. can u help me please…

  15. Gahoot

    hi all
    can anyone help me out, to connect IOU Switch of GNS3 to physical router or switch, I am tired trying

    1. Jared

      At this time, it’s not possible to get IOU virtual switch directly connected to outside network. You have to use a IOS-based virtual switch.


Leave a Reply

Your email address will not be published. Required fields are marked *