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How To Enable Open vSwitch in XenServer 6

A topic that is way under-covered in the blogosphere is definitely Citrix XenServer so I figured I would add XenServer to the list of topics I cover from time to time. This week I want to cover Open vSwitch, a virtual switch that can be enabled inside XenServer 6. Now for those of you that don't know, Open vSwitch were introduced with XenServer 5.6 FP1 and as a result all XenServer versions after that support it, except it has to be enabled.

A little bit of background: By default XenServer's backend networking uses Linux bridge, an Ethernet networking bridging code used to connect two segments. It is the standard networking code you find in Linux distributions, it has many advantages but it also has a very basic feature set.

The Open vSwitch, on the other hand, has a very rich feature set that includes:

  • ACLs and QoS policies
  • NetFlow
  • Traffic mirroring
  • Port bonding
  • Per VM traffic policy

Open vSwitch has features are very desirable by any network administrator, but if that was not a good enough reason to use it, well add to it the fact that in order to use Citrix XenServer’ Distributed virtual switching technology, you must enable the Open vSwitch on every XenServer that will participate.

To enable Open vSwitch, connect to the console of each XenServer and run the following command:

xe-switch-network-backend openvswitch

You must restart the XenServer host after initiating this command in order for the changes to take effect. Now, if you want to switch back to Linux bridge, you issue this command:

xe-switch-network-backend bridge

You should use caution as you switch back to Linux bridge, especially if High Availability is enabled in your environment. If that is the case, follow these steps to switch back to Linux bridge:

  1. Disable High Availability
  2. MIGRATE VMs to a different XenServer host
  3. Enable Linux bridge mode by using the command above
  4. Reboot the XenServer host
  5. Migrate VMs back
  6. Enable High Availability

Since this is my first blog on XenServer, I would really appreciate your feedback either in the comments section or via e-mail at [email protected] or Twitter at I am interested to know if you found this particular blog to be useful and if you want to see more XenServer coverage here.

Posted by Elias Khnaser on 04/03/2012 at 12:49 PM


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