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I have 2 domU virtual machines installed on a 11.10 Oneiric Dom0. My internal network is on the 192.168.1 subnet, and when the domU's start, they get ips on the 192.168.122 subnet. I have attempted to follow the instructions here :

xend-config.sxp is configured correctly, but neither of my domU's have a config file in /etc/xen to modify. ifconfig reports that I have the following devices :

eth0, lo, tap3.0, vif3.0, vif4.0, virbr0

bridge-utils is installed. I also just attempted to follow these steps :

sudo brctl addbr xenbr0
sudo brctl addif xenbr0 vif3.0
device vif3.0 is already a member of a bridge; can't enslave it to bridge xenbr0.

Any ideas on next steps are greatly appreciated!

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The issue boiled down to 2 items:

  • establishing a bridged network interface (xenbr0), and
  • learning how to configure existing domU's which did not have configuration files.

Establishing a bridged network interface (xenbr0):

Compiling information from here.

  1. added the following to /etc/network/interfaces:

    auto xenbr0
    iface xenbr0
    bridge_ports eth0
    bridge_stp on
    bridge_maxwait 0
    bridge_fd 0
  2. simply restarting networking didn't do the trick, but restarting the machine and running ifconfig returned :

    xenbr0    Link encap:Ethernet  HWaddr 50:e5:49:e6:bd:e2  
              inet addr:  Bcast:  Mask:

    brctl show returned :

    bridge name bridge id       STP enabled interfaces
    virbr0      8000.000000000000   yes     
    xenbr0      8000.50e549e6bde2   yes     eth0

    The key here being the eth0 listed as an interface for xenbr0.

Once xenbr0 is configured, we can configure the domU's to use it as their interface.

Using method 2 found here :

  • Export the virtual machines configuration xm list -l SLES10 > sles10 where "SLES10" is your domU's name
  • Backup the file sles10, you may need it in the event that something is corrupted.
  • Open the file sles10 for editing
  • Locate the line reading

    (bridge virbr0)
  • Change it to

    (bridge eth0)
  • Save the file
  • Reimport the new configuration

    xm new -F sles10

    Upon restart, both domU's are now on the 192.168.1 subnet.

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