[ovs-dev] Question about ovn-controller CLEAR_FLOWS state

Ben Pfaff blp at ovn.org
Sun Apr 10 20:55:50 UTC 2016


On Wed, Apr 06, 2016 at 11:34:05AM +0800, 张东亚 wrote:
> Recently I am reading ovn source code, there are some STATES before OVN
> controller shift to UPDATE_FLOWS state, one state is named CLEAR_FLOWS,
> which seems clear all the flows in the ovs-vswitchd before programming new
> flows, IMHO this will cause short traffic disruption for the VM hosted on
> the node.
> 
> Since in neutron l2 agent, there is now a flow persistence mechanism by
> leveraging  flow cookie, the effect is that when the l2 agent is restarted,
> flow will be keeped if network topology is not changed.
> 
> My question is whether ovn will implement this feature laterly or consider
> this feature is useless?

It doesn't seem very valuable for OVN.  It's probably better for
ovn-controller to support the OpenFlow "bundles" feature so that flow
table changes become atomic.



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