Some embodiments of the invention provide a method for reporting congestion in a network that includes several forwarding elements. In a data plane circuit of one of the forwarding elements, the method detects that a queue in the switching circuit of the data plane circuit is congested, while a particular data message is stored in the queue as it is being processed through the data plane circuit. In the data plane circuit, the method then generates a report regarding the detected queue congestion, and sends this report to a data collector external to the forwarding element. To send the report, the data plane circuit in some embodiments duplicates the particular data message, stores it in the duplicate data message information regarding the detected queue congestion, and sends the duplicate data message to the external data collector.