Comment 7 for bug 1774459

One other simple solution would be to forward a packet ( GARP ) for the MAC's that are configured for Allowed_address_pair to the Ryu controller. The controller can process the packet under the 'packet_in_handler' and then try to create an ARP response entry in the ARP Responder for the MAC and IP.

Before writing the entry probably we should check for the current flows configured in the ARP Responder table and if there is a duplicate entry for the IP/MAC combination, then delete it and rewrite the flows for the GARP packet.

Today we don't have a packet_in_handler for the Ryu controller app.
Similar to this.
@handler.set_ev_cls(ofp_event.EventOFPPacketIn, handler.MAIN_DISPATCHER)
def packet_in_handler(self, ev):
    pkt = packet.Packet(array.array('B', ev.msg.data))
    for p in pkt:
        print p.protocol_name, p

My knowledg is pretty limited in L2 openflow, so if there are any L2 Openflow experts could comment on this, if this would work or not.