A data-driven intelligent networking system that can facilitate tracing of data flow packets is provided. The system add tracer packets to data flow packets arriving at an ingress point of the network. As the tracer packets progress through network in-band with the data flow packets, the system can copy, at each switch, trace data into pre-defined fields in the tracer packets. When the data flow packets arrive at an egress point of the network the system can separate the trace data from the data flow packet for analysis. Based on the analysis of the trace data, the system can adopt one or more policies to mitigate the impact of congestion on time-sensitive applications.