Automatic Discovery of Multiple Controllers in Software Defined Networks (SDNs)

A method to check health of automatically discovered controllers comprising the steps of:

• a) a first controller generating a first Controller-Advertisement message carrying the information required to identify and access said first controller when a new switch port becomes active;
• b) said first controller sending said generated first Controller-Advertisement message to a first switch having said newly activated port;
• c) said first controller receiving at least a second Controller-Advertisement message from at least a second controller;
• d) said first controller generating a third unsolicited Controller-Advertisement message with its access information to check health of said second controller;
• e) said first controller receiving at least a fourth Controller-Advertisement message from said second controller indicating health information of said second controller, wherein said health information is stored in first controller's Controller Information Base (CIB).

A method for a first controller in a first subnetwork to automatically discover a second controller of a second subnetwork, said first subnetwork further comprising at least a first switch and said second subnetwork further comprising at least a second switch, said method as implemented in said first controller comprising the steps of:

• a) receiving a message from said first switch identifying activation of a first port, which is due to establishment of a connection between a first port in said first switch and a second port in said second switch;
• b) generating a Controller-Advertisement message carrying information required to identify and access said first controller;
• c) forwarding said generated Controller-Advertisement message from said first controller to said first switch, said first port in said first switch further forwarding said Controller-Advertisement message to said second port in said second switch, said second switch further forwarding said Controller-Advertisement message to said second controller along with an identification of said second port over which said Controller-Advertisement message was received;
• d) if said first controller and said second controller are a single controller, then:
• i. updating said single controller's Network Information Base (NIB) with a new entry showing new connection information between said first switch and said second switch, utilizing the information carried in the optional switch-id and port-no fields of said Controller-Advertisement message, and
• ii. discarding any Controller-Advertisement messages that are looped to itself.
• e) if said first controller and said second controller are different controllers, then said second controller:
• i. identifying said first controller using information carried in said Controller-Advertisement message originated from said first controller;
• and
• ii. generating a new Controller Information Base (CIB) entry containing information for said first controller.

An article of manufacture having computer readable storage medium comprising computer readable program code executable by a computer to implement a method for a first controller in a first subnetwork to automatically discover a second controller of a second subnetwork, said first subnetwork further comprising at least a first switch and said second subnetwork further comprising at least a second switch, said medium comprising:

• a) computer readable program code executed by said computer to receive a message from said first switch identifying activation of a first port, which is due to establishment of a connection between a first port in said first switch and a second port in said second switch;
• b) computer readable program code executed by said computer to generate a Controller-Advertisement message carrying information required to identify and access said first controller;
• c) computer readable program code executed by said computer to forward said generated Controller-Advertisement message from said first controller to said first switch, said first port in said first switch further forwarding said Controller-Advertisement message to said second port in said second switch, said second switch further forwarding said Controller-Advertisement message to said second controller along with an identification of said second port over which said Controller-Advertisement message was received;
• wherein said second controller in said second subnetwork identifies said first controller in said first subnetwork based on information carried in said Controller-Advertisement message, and said second controller generating a Controller Information Base (CIB) entry containing information required to identify and access said first controller.

An article of manufacture having computer readable storage medium comprising computer readable program code executable by a computer to implement a method for a first controller in a first subnetwork to automatically discover a second controller of a second subnetwork, said first subnetwork further comprising at least a first switch and said second subnetwork further comprising at least a second switch, said method as implemented in said first controller comprising the steps of:

• a) computer readable program code executed by said computer to receive a message from said first switch identifying activation of a first port, which is due to establishment of a connection between a first port in said first switch and a second port in said second switch;
• b) computer readable program code executed by said computer to generate a Controller-Advertisement message carrying information required to identify and access said first controller;
• c) computer readable program code executed by said computer to forward said generated Controller-Advertisement message from said first controller to said first switch, said first port in said first switch further forwarding said Controller-Advertisement message to said second port in said second switch, said second switch further forwarding said Controller-Advertisement message to said second controller along with an identification of said second port over which said Controller-Advertisement message was received;
• d) if said first controller and said second controller are a single controller, then:
• i. computer readable program code executed by said computer to update said single controller's Network Information Base (NIB) with a new entry showing new connection information between said first switch and said second switch, utilizing the information carried in the optional switch-id and port-no fields of said Controller-Advertisement message, and
• ii. computer readable program code executed by said computer to discard any Controller-Advertisement messages that are looped to itself.
• e) if said first controller and said second controller are different controllers, then said second controller:
• i. computer readable program code executed by said computer to identify said first controller using information carried in said Controller-Advertisement message originated from said first controller;
• and
• ii. computer readable program code executed by said computer to generate a new Controller Information Base (CIB) entry containing information for said first controller.