prevent broadcast traffic to be sent to every tunnel endpoint

While using the OVS GRE encapsulation, when a broadcast packet is sent, every tunnel endpoint will receive it, even if the tunnel endpoint has no device in the concerned network. The traffic is bothered by unecessary broadcast traffic.
This could be improved by populating a relationship between endpoints and networks as soon as a port of the network is created in the hypervisor/tunnel endpoint. The flow in the br-tun will also be changed so that traffic from br-int will still have the action "set-tunnel" but will have the the action "output:tunnel_1,...,tunnel_n" instead of NORMAL.