Charms don't support user-space tunnelling (VXLAN/Geneve) with OVS-DPDK DVR

The configuration that we tested had OVS-DPDK bond for the data port and data binding configured on the kernel bonded VLAN interface (bond1.203) (see the bundle config. below).
In that configuration OVS DPDK doesn't seem to forward any data to the *overlay-space subnet and running tcpdump over the bond1.203 interface confirms that.

As per the official HOWTO from Openvswitch [1] OVS running in userspace (DPDK) requires the configuration of the layer 3 that is different from what neutron-openvswitch does currently, specificically, the L3 must be configured on the OVS bridge that has bond1.203 as a port:

"This additional bridge is required when running Open vSwitch in userspace rather than kernel-based Open vSwitch. The purpose of this bridge is to allow use of the kernel network stack for routing and ARP resolution. The datapath needs to look-up the routing table and ARP table to prepare the tunnel header and transmit data to the output port."

At the moment docs for the neutron-openvswitch charm say that "Currently, this charm supports use of DPDK enabled devices in bridges supporting connectivity to provider networks.", so it is possible an easy useful improvement just to state more explicitly that OVS DPDK VXLAN are not supported by the charm.

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PS: I'm not sure if it makes sense to fix the charm to support overlay tunnel networks with OVS DPDK DVR, but here is some extra information on the topic.

I used the custom script inspired by [1] to re-configure existing deployment to OVS bridges: https://pastebin.canonical.com/p/7qG9VgKX9T/
After I did that DPDK VXLAN VMs was able to reach metadata and DHCP servers and ping each other.

But the next problem I faced was that ARP replies to 'who-has' from the external router were not sent back from FIP namespace. And also I couldn't ping the external router from the FIP namespace of DPDK machine
So I decided to stop here.
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[1] http://docs.openvswitch.org/en/latest/howto/userspace-tunneling/