Setting Up Multiple Virtual Networks

Some deployments may require more than one network interface and address.  Datapipe's EPN allows you to create virtual networks and assign multiple network interfaces to individual virtual machines.  You may want to do this to separate and isolate network traffic or as a another layer of security.  The following illustration demonstrates how this might look:

Multiple Networks

In the above example, machines "A" and "B" can communicate with each other.  Machines "C" and "D" can communicate with each other.  But machine "A" cannot communicate with "C" or "D" unless it goes through "B" which has an interface in both networks.

To set something like this up, create as many virtual networks as will be required.  Remember, however, you can only have ONE default network.  All subsequent networks must be set up as non-default.  SEE below:

Epn Step 5b

When you create virtual machines, you will be presented with all of the virtual networks you have defined.  That will look something like the following:

Multiple Interfaces

You must select one of the default networks, ("your_network" in the above illustration).  The "Additional Networks" are optional.  You can select up to 8--provided, of course, that you defined that many.

Note:   Some Linux distributions do not automatically configure the secondary adapters.  If you add a second network but do not see it, from the command line do "ifconfig -a".  The device should be visible.  To bring this interface on line, do the following:

1) As root, "cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth1";  

2) "vi /etc/sysconfig/network-scripts/ifcfg-eth1";  

3) Replace the first line, "DEVICE=eth0" with "DEVICE=eth1". Press ":" then "wq" to quit and save;

4) "ifup eth1"

Now, when you do "ifconfig", you will see the interfaces with the dhcp addresses they acquired. This will be permanent so if/when you reboot, the second NIC will continue to come online.