[ovs-discuss] Controllability of OpenFlow Controllers

Justin Pettit jpettit at nicira.com
Mon Jul 4 20:49:36 UTC 2011

On Jul 4, 2011, at 3:38 AM, Wei-Chih Chen wrote:

>> The ovs-ofctl commands are mostly just making OpenFlow calls through a command line utility, so no there is really no difference.  The ovs-vsctl and ovs-dpctl commands configure the OVS configuration database and kernel modules, respectively.
>> The XCP community was likely saying that some elements of configuration should be done through XAPI and others over OpenFlow.  There is some overlap, so doing things like adding ports to a bridge should be done through XAPI instead of directly with ovs-vsctl, so that XAPI doesn't get confused.  Internally, XAPI is making those same ovs-vsctl commands.  
> Does this mean XAPI does the same effects as what ovs-vsctl commands?
> Or XAPI calls ovs-vsctl commands as its backend?

The latter.

>> Things that have no overlap (because XAPI has no concept of them), such as flow configuration must be done through done through ovs-ofctl or an OpenFlow controller.
>> Products such as Citrix's DVS (Distributed Virtual Switch) make both XAPI and OpenFlow calls depending on what is being configured. 
> Does vSwitch Controller configure Open vSwitch on XenServer/XCP through OpenFlow protocol, instead of ovs- commands? 

Something with centralized control, like Citrix's DVS, is generally going to speak the OpenFlow protocol.  It's possible to make the ovs-ofctl interact with a remote system, but I would imagine this would mostly be done be a script-driven controller that doesn't have particularly high scaling requirements.


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