17.15. Creating Tunnels

This section will demonstrate how to implement different tunneling scenarios.

17.15.1. Creating Multicast Tunnels

A multicast group is setup to represent a virtual network. Any guest virtual machines whose network devices are in the same multicast group can talk to each other even across host physical machines. This mode is also available to unprivileged users. There is no default DNS or DHCP support and no outgoing network access. To provide outgoing network access, one of the guest virtual machines should have a second NIC which is connected to one of the first four network types thus providing appropriate routing. The multicast protocol is compatible the guest virtual machine user mode. Note that the source address that you provide must be from the address used for the multicast address block.
To create a multicast tunnel place the following XML details into the <devices> element: 
      
  ...
  <devices>
    <interface type='mcast'>
      <mac address='52:54:00:6d:90:01'>
      <source address='230.0.0.1' port='5558'/>
    </interface>
  </devices>
  ...

Figure 17.28. Multicast tunnel domain XMl example

17.15.2. Creating TCP Tunnels

A TCP client-server architecture provides a virtual network. In this configuration, one guest virtual machine provides the server end of the network while all other guest virtual machines are configured as clients. All network traffic is routed between the guest virtual machine clients via the guest virtual machine server. This mode is also available for unprivileged users. Note that this mode does not provide default DNS or DHCP support and it does not provide outgoing network access. To provide outgoing network access, one of the guest virtual machines should have a second NIC which is connected to one of the first four network types thus providing appropriate routing.
To create a TCP tunnel place the following XML details into the <devices> element: 
      
       ...
  <devices>
    <interface type='server'>
      <mac address='52:54:00:22:c9:42'>
      <source address='192.168.0.1' port='5558'/>
    </interface>
    ...
    <interface type='client'>
      <mac address='52:54:00:8b:c9:51'>
      <source address='192.168.0.1' port='5558'/>
    </interface>
  </devices>
  ...

Figure 17.29. TCP tunnel domain XMl example