The embodiment of the invention discloses a method for establishing an in-band
control channel of a
software defined network (SDN), and a device, and relates to the field of communication. A transmission port of an
OpenFlow switching device can be recorded to obtain a transmission path of an In-band control message. The method comprises the following steps: establishing and enabling a first flow table, wherein the first flow table is used for indicating to process a message whose destination
internet protocol (IP) address is a local
IP address by an upper layer protocol; sending an
address resolution protocol (ARP) request whose destination
IP address is the
IP address of an SDN controller, and after ARP response matched with the first flow table is received, recording the port receiving the ARP response as an uplink outlet port; establishing and enabling a second flow table, wherein the second flow table is used for indicating to process a port discovery message by a
control layer; after port discovery messages matched with the second flow table and sent by other
OpenFlow switching devices are received, recording the IP addresses of the other
OpenFlow switching devices, and recording the ports receiving the port discovery messages as downlink outlet ports corresponding to the other OpenFlow switching devices, and forwarding the discovery messages from the uplink outlet port.