The idea of connecting a virtual network device or a whole virtual network infrastructure with the real network sounds very attractive!!! In the case of GNS3 is possible and easy to implement. Let’s do it!
First of all, we have to create a new project. Also, we can open a previous working project.
Then we add a router, in our case we have chosen a Cisco 3600,
with at least 1 Ethernet or FastEthernet interface.
Then we drag and drop the cloud icon in our network map.
We right click on the cloud and select configure.
From the tab NIO Ethernet we select the option that represents the real network interface in our workstation and we press the button Add.
Then press ok button to close the cloud configuration window. Now, let’s connect our virtual router to the cloud that represents our real network. Click on the Add Link button and we select the option Manual.
The cursor becomes cross mark. Click on the cloud and from the popup option select the real interface item, as the one we created in previous step.
Then a line will be connected with the cloud icon and will follow the cross mark cursor. Now click the router icon and select an interface from the options box.
The link between the cloud (real network) and the virtual router is established.
We can start our devices by pressing the green triangle button (play button). The router will start booting. We can watch the booting procedure in the console by right clicking on the router icon and selecting the console option from the popup menu.
Now we can assign an ip address of the real subnet on the connected interface of the router. In our case my real subnet is 192.168.3.0/24, so I assign the address 192.168.3.100 255.255.255.0 to the Fast Ethernet 0/0 interface.
R1> R1>en R1#conf t Enter configuration commands, one per line. End with CNTL/Z. R1(config)#interface fa0/0 R1(config-if)#ip address 192.168.3.100 255.255.255.0 R1(config-if)#no shutd
Now, if everything have been done fine, we should have a successful ping to our real network or any real network device (workstations, servers, etc.)
This was a simple example of how to connect a GNS3 virtual network to the real network. Of course, we could have a more complex virtual network, running a routing protocol and communicate with the real devices.
I hope I will get some feedback of yours.
Enjoy!!!