-- binary
01 0a # version / type
00 15 # length
12 34 56 78 # xid
ab cd ef 01 # buffer_id
00 09 # total_len
ff fe # in_port
01 # reason
00 # pad
61 62 63 # data
-- python
ofp.message.packet_in(
    xid=0x12345678,
    buffer_id=0xabcdef01,
    total_len=9,
    in_port=ofp.OFPP_LOCAL,
    reason=ofp.OFPR_ACTION,
    data='abc')