The Path Diagnostics application determines and verifies the path taken by trace packets from a source host to a destination host. The application finds an existing flow that matches the description of the trace packet, clones it with higher priority and adds an additional action to instruct the selected switch to send this packet back to the controller for status tally.

The Path Diagnostics application is available when the ControllerManager configuration has hybrid.mode=false only.

Each flow-mod is assigned an idle timeout value, which specifies how long the flow-mod will remain in the device if the flow-mod is not actively being used. Each flow-mod is also assigned a hard timeout value, which specifies how long the flow-mod will remain in the datapath (regardless of usage). The com.hp.sdn.ctl.path.impl.PathDiagnosticManager configurable component of the controller enables the controller administrator to configure each of these parameters using the idle.timeout (default 300 seconds) and hard.timeout (default 300 seconds) keys.