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

[张东亚]

Hi list,

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?

Thanks a lot.