Some embodiments provide a method for performing data traffic monitoring. The method processes a packet through a packet processing pipeline that includes multiple stages. At a filtering stage, the method tags the packet with a set of monitoring actions for subsequent stages to perform on the packet based on a determination that the packet matches a particular filter. For each stage of a set of packet processing stages subsequent to the filtering stage, the method (i) executes any monitoring actions specified for the stage to perform on the packet and (ii) sends the packet to a next stage in the packet processing pipeline.