$ ./trema run loopback-test.rb
[switch_ready]
  datapath_id: 0x2320cb14bb
[features_request]
  datapath_id: 0x2320cb14bb
[features_reply]
  datapath_id: 0x2320cb14bb
  port number: 1(Port up)
    hardware address: 10:6f:3f:07:d3:6f
    name: eth0.1
[packet_out]
  datapath_id: 0x2320cb14bb
  out_port: 1
  port number: 2(Port up)
    hardware address: 10:6f:3f:07:d3:6f
    name: eth0.2
[packet_out]
  datapath_id: 0x2320cb14bb
  out_port: 2
  port number: 3(Port up)
    hardware address: 10:6f:3f:07:d3:6f
    name: eth0.3
[packet_out]
  datapath_id: 0x2320cb14bb
  out_port: 3
  port number: 4(Port up)
    hardware address: 10:6f:3f:07:d3:6f
    name: eth0.4
[packet_out]
  datapath_id: 0x2320cb14bb
  out_port: 4
[packet_in]
  datapath_id: 0x2320cb14bb
  data: wildcards = 0, in_port = 1, dl_src = 00:00:00:00:00:01, dl_dst = 00:00:00:00:00:02, dl_vlan = 65535, dl_vlan_pcp = 0, dl_type = 0x800, nw_tos = 0, nw_proto = 17, nw_src = 192.168.0.1/32, nw_dst = 192.168.0.2/32, tp_src = 1, tp_dst = 1
[barrier_reques]
  datapath_id: 0x2320cb14bb
[packet_in]
  datapath_id: 0x2320cb14bb
  data: wildcards = 0, in_port = 2, dl_src = 00:00:00:00:00:01, dl_dst = 00:00:00:00:00:02, dl_vlan = 65535, dl_vlan_pcp = 0, dl_type = 0x800, nw_tos = 0, nw_proto = 17, nw_src = 192.168.0.1/32, nw_dst = 192.168.0.2/32, tp_src = 1, tp_dst = 1
[barrier_reques]
  datapath_id: 0x2320cb14bb
[barrier_reply]
  datapath_id: 0x2320cb14bb
[barrier_reply]
  datapath_id: 0x2320cb14bb
[flow_removed]
  datapath_id: 0x2320cb14bb
  match: wildcards = 0, in_port = 1, dl_src = 00:00:00:00:00:01, dl_dst = 00:00:00:00:00:02, dl_vlan = 65535, dl_vlan_pcp = 0, dl_type = 0x800, nw_tos = 0, nw_proto = 17, nw_src = 192.168.0.1/32, nw_dst = 192.168.0.2/32, tp_src = 1, tp_dst = 1
[flow_removed]
  datapath_id: 0x2320cb14bb
  match: wildcards = 0, in_port = 2, dl_src = 00:00:00:00:00:01, dl_dst = 00:00:00:00:00:02, dl_vlan = 65535, dl_vlan_pcp = 0, dl_type = 0x800, nw_tos = 0, nw_proto = 17, nw_src = 192.168.0.1/32, nw_dst = 192.168.0.2/32, tp_src = 1, tp_dst = 1