Yes, unfortunately right now all of the inter-bridge connections are wiped out and recreated along with all of the OF rules and it's not configurable behavior.[1]

I believe there are plans to fix this in Liberty, but the changes will likely be too invasive to be back-ported to Juno and Kilo.

1. https://github.com/openstack/neutron/blob/stable/juno/neutron/plugins/openvswitch/agent/ovs_neutron_agent.py#L865

On Sun, May 3, 2015 at 12:33 AM, Sławek Kapłoński <slawek@kaplonski.pl> wrote:
Hello,

AFAIK it is because of recreation of all openflow rules in ovs - that is
at least on my infra where we're using vxlan tunnels with l2population
mechanism.
I would be happy if there will be any solution to not recreate all
tunnels when agent is restarted.

--
Best regards / Pozdrawiam
Sławek Kapłoński
slawek@kaplonski.pl

On Thu, Apr 30, 2015 at 03:49:24PM +0700, Chris wrote:
> Hello,
>
>
>
> We made some changes on our compute nodes in the
> "/etc/neutron/neutron.conf". For example qpid_hostname. But nothing what
> effects the network infrastructure in the compute node.
>
> To apply the changes I think we need to restart the
> "neutron-openvswitch-agent" service.
>
>
>
> By restarting this service the VM gets disconnected for around one ping, the
> reason is the restart causes recreation of the int-br-bond0 and phy-br-bond0
> interfaces:
>
> ovs-vsctl: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=10 --
> --may-exist add-br br-int
>
> ovs-vsctl: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=10 --
> set-fail-mode br-int secure
>
> ovs-vsctl: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=10 --
> --if-exists del-port br-int patch-tun
>
> ovs-vsctl: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=10 --
> --if-exists del-port br-int int-br-bond0
>
> kernel: [73873.047999] device int-br-bond0 left promiscuous mode
>
> ovs-vsctl: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=10 --
> --if-exists del-port br-bond0 phy-br-bond0
>
> kernel: [73873.086241] device phy-br-bond0 left promiscuous mode
>
> ovs-vsctl: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=10 --
> --may-exist add-port br-int int-br-bond0
>
> kernel: [73873.287466] device int-br-bond0 entered promiscuous mode
>
> ovs-vsctl: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=10 --
> --may-exist add-port br-bond0 phy-br-bond0
>
>
>
> Is there a way to apply this changes without loose pings?
>
>
>
> Cheers
>
> Chris
>

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--
Kevin Benton