Abstract: A method implemented by a first controller in a software defined networking (SDN) network to monitor a health of a second controller, where the first controller and the second controller are part of a cluster of controllers, where controllers in the cluster communicate with switches over an in-band network, and where controllers in the cluster communicate with each other over an out-of-band network. The method includes sending a first control message to a switch over the in-band network in response to a determination that the second controller cannot be reached over the out-of-band network, where the first control message includes a health check request message and an instruction for the switch to send the health check request message to the second controller, and where the switch is a designated switch that has a control channel connection to the first controller and the second controller over the in-band network.

Abstract: A method implemented by a switch in a Software Defined Networking (SDN) network to trace packets in the SDN network, where the switch includes a packet processing pipeline. The method includes receiving a first packet, determining, at a first flow table of the packet processing pipeline, whether the first packet is to be traced, punting a copy of the first packet to an SDN controller and directing the first packet to a second flow table of the packet processing pipeline in response to a determination at the first flow table that the first packet is to be traced.

Abstract: A system for tracing packets in a Software Defined Networking (SDN) network. The system includes a switch and an SDN controller communicatively coupled to the switch. The SDN controller is configured to program a packet processing pipeline of the switch to cause the switch to determine, at a first flow table of the packet processing pipeline, whether a packet is a trace packet that was recirculated based on content of a first field associated with the packet and in response to a determination that the packet is a trace packet that was recirculated, set a first field associated with the packet to indicate that tracing is disabled for the packet, set a second field associated with the packet to indicate that tracing is enabled for the packet, determine a flow table of the packet processing pipeline from which the packet was recirculated, and direct the packet to that flow table.

Abstract: A method is implemented by a switch in a Software Defined Networking (SDN) network to trace packets, where the switch includes a packet processing pipeline that includes a plurality of flow tables. The method includes receiving a packet, determining, at a first flow table of the packet processing pipeline, whether the packet is a trace packet that was recirculated based on content of a first field associated with the packet, and in response to a determination that the packet is trace packet that was recirculated, setting a first field associated with the packet to indicate that tracing is disabled for the packet, setting a second field associated with the packet to indicate that tracing is enabled for the packet, determining a flow table of the packet processing pipeline from which the packet was recirculated, and directing the packet to the flow table from which the packet was recirculated.

Abstract: A method implemented by a network device to reduce bandwidth and compute resources needed by a controller of a software defined networking (SDN) network by distributing monitoring of nodes connected to data plane nodes (DPNs) in an SDN network. The method determines whether a received response message from a node indicates proper operation, inserts parameters of the received response message into a template for a stateful request message, and sends the stateful request message to the node.

Abstract: A method implemented by a switch in a software defined networking (SDN) network to monitor a service node communicatively coupled to the switch. The method includes generating a first flow entry that matches packets received from the service node, generating a second flow entry that matches packet received from the service node, wherein the second flow entry has a priority that is lower than a priority of the first flow entry, removing the first flow entry and transmitting a flow removed message to an SDN controller in response to a determination that the first flow entry has timed out, maintaining a statistic associated with the second flow entry, and transmitting a statistics trigger event message to the SDN controller in response to a determination that the statistic associated with the second flow entry exceeds a threshold value.

Abstract: A method implemented by a first switch in a software defined networking (SDN) network to monitor a tunnel between the first switch and a second switch in the SDN network. The method includes generating a first flow entry that matches packets received over the tunnel, generating a second flow entry that matches packet received over the tunnel, where the second flow entry has a priority that is lower than a priority of the first flow entry, removing the first flow entry and transmitting a flow removed message to an SDN controller in response to a determination that the first flow entry has timed out, maintaining a statistic associated with the second flow entry, and transmitting a statistics trigger event message to the SDN controller in response to a determination that the statistic associated with the second flow entry exceeds a threshold value.