Message Type of Open Flow

# enum ofp_type
OFPT_HELLO = 0 # Symmetric message
OFPT_ERROR = 1 # Symmetric message
OFPT_ECHO_REQUEST = 2 # Symmetric message
OFPT_ECHO_REPLY = 3 # Symmetric message
OFPT_VENDOR = 4 # Symmetric message
OFPT_FEATURES_REQUEST = 5 # Controller/switch message
OFPT_FEATURES_REPLY = 6 # Controller/switch message
OFPT_GET_CONFIG_REQUEST = 7 # Controller/switch message
OFPT_GET_CONFIG_REPLY = 8 # Controller/switch message
OFPT_SET_CONFIG = 9 # Controller/switch message
OFPT_PACKET_IN = 10 # Async message
OFPT_FLOW_REMOVED = 11 # Async message
OFPT_PORT_STATUS = 12 # Async message
OFPT_PACKET_OUT = 13 # Controller/switch message
OFPT_FLOW_MOD = 14 # Controller/switch message
OFPT_PORT_MOD = 15 # Controller/switch message
OFPT_STATS_REQUEST = 16 # Controller/switch message
OFPT_STATS_REPLY = 17 # Controller/switch message
OFPT_BARRIER_REQUEST = 18 # Controller/switch message
OFPT_BARRIER_REPLY = 19 # Controller/switch message
OFPT_QUEUE_GET_CONFIG_REQUEST = 20 # Controller/switch message
OFPT_QUEUE_GET_CONFIG_REPLY = 21 # Controller/switch message