GNS3 provides a way to connect the simulated network to the real network through its cloud interface. A cloud represents a generic network interface the details of which are abstracted from the network simulated inside the GNS3.
When I say real network, I mean the network to which your Network Adapter is connected to. The network could be a private LAN or the Internet. My network adapter is connected to Internet via the cable modem (Hathway) and I want to connect the GNS3 network to it.
To keep things simple, let’s create a network that has a switch and a couple of PCs.
Here are the steps to connect the GNS3 network with the real network (Internet) :
Step #1 : Drag and drop the Cloud object into the work space.
Step #2 : Configure the Cloud interface.
Right click on the Cloud and select configure from the context menu.
In the cloud configuration, under Ethernet tab, you’ll find a list of network adapters your PC has. Now whichever network adapter you select, the cloud represents it. I’ve connected to the Internet via the adapter named Ethernet. Your case may differ.
After selecting the right network adapter, make sure you click Add button and notice the adapter being added in the box below it. Then click OK.
Step #3 : Connect the network to the cloud.
Step #4 : Configure the network devices appropriately.
Since our example network is very simple with only one switch, all we have to do is tell the PCs to get their IP addresses from the DHCP server running on the Cloud. Note that the Cloud is in turn connected through the Ethernet adapter to the cable modem on which the DHCP service is running.
The PCs are VPCS’es running in GNS3. Note that the DHCP server handed out a public IP address from its pool to our VPCS PC1. Same events occur for two VPCS’es.
Depending on the configuration of the modem, we can connect several simulated PCs from within the GNS3 to the Internet.
Step #5 : Verify the connectivity.
Since the GNS3 network in this case is connected to the Internet, I’ll verify the connectivity by pinging to google.com. If the GNS3 is connected to a private LAN, we should verify the connectivity by pinging the gateway as well as other nodes.
There you go! We have created a network inside GNS3 and connected it to the real network such as the Internet.