Device detection

A Software Defined Network (SDN) controller, comprising:

• a processor;
• and a non-transitory machine-readable storage medium to store machine-executable instructions which are executable by the processor to:
• receive a detecting packet which is sent by a first switch and initiated by a first device accessing the first switch, wherein the detecting packet carries an identifier of a Virtual Local Area Network (VLAN) to which the first device belongs;
• send, for each of switches having an SDN connection with the SDN controller, the detecting packet and information of all downlink ports of the switch having an SDN connection with the SDN controller to the switch having an SDN connection with the SDN controller in a way that the switch having an SDN connection with the SDN controller sends the detecting packet through the downlink port without checking whether the identifier of the VLAN carried in the detecting packet matches an identifier of Permit VLAN configured on the downlink port;
• receive a response packet which is sent by a second switch, wherein the response packet is sent by a second device accessing the second switch to the second switch in response to receiving the detecting packet, wherein an Internet Protocol (IP) address of the second device matches a destination IP address of the detecting packet;
• and send forwarding configuration information to the second switch in a way that the second switch configures a port through which the response packet is received.

A non-transitory machine-readable storage medium storing machine executable instructions which are invoked and executed by the processor to:

• receive a detecting packet which is sent by a first switch and initiated by a first device accessing the first switch, wherein the detecting packet carries an identifier of a Virtual Local Area Network (VLAN) to which the first device belongs;
• send, for each of switches having an Software Defined Network (SDN) connection with the SDN controller, the detecting packet and information of all downlink ports of the switch having an SDN connection with the SDN controller to the switch having an SDN connection with the SDN controller in a way that the switch sends the detecting packet through the downlink port without checking whether the identifier of the VLAN carried in the detecting packet matches an identifier of Permit VLAN configured on the downlink port;
• receive a response packet which is sent by a second switch, wherein the response packet is sent by a second device accessing the second switch to the second switch in response to receiving the detecting packet, wherein an Internet Protocol (IP) address of the second device matches a destination IP address of the detecting packet;
• and send forwarding configuration information to the second switch in a way that the second switch configures a port through which the response packet is received.