Tracing logical network packets through physical network

A method for processing a flow trace packet at a particular managed forwarding element (MFE), the method comprising:

• receiving a flow trace packet having source and destination addresses in a logical network implemented by the particular MFE;
• processing the flow trace packet based on the logical network addresses;
• and
• sending a message to a network controller regarding the processing of the flow trace packet, the message comprising (i) data identifying the particular MFE and (ii) data identifying an action taken by the particular MFE based on the processing of the flow trace packet.

A non-transitory machine-readable medium storing a particular managed forwarding element (MFE) which when executed by at least one processing unit processes a flow trace packet, the program comprising sets of instructions for:

• receiving a flow trace packet having source and destination addresses in a logical network implemented by the particular MFE;
• processing the flow trace packet based on the logical network addresses;
• and
• sending a message to a network controller regarding the processing of the flow trace packet, the message comprising (i) data identifying the particular MFE and (ii) data identifying an action taken by the particular MFE based on the processing of the flow trace packet.