OVS CheatSheet

Tracing Packet flows
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ovs-dpctl -s show
ovs-dpctl dump-flows ovs-system

ovs-vsctl: Error detected while setting up 'gtpu0': could not add network device gtpu0 to ofproto (Address family not supported by protocol).  See ovs-vswitchd log for details.
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Only 2 reasons :
   1. The tunnel end-point is not in same subnet
   2. GTP is not integrated in the openvswitch 
               Interface gtp0
                type: gtpu
                options: {key=flow, remote_ip=flow}
                error: "could not add network device gtp0 to ofproto (Address family not supported by protocol)"