This paper describes an environment for visualizing packet traces that greatly simplifies troubleshooting protocol implementations. Network management centers routinely collect packet traces to tally traffic statistics and to troubleshoot protocol configuration and implementation problems. Previous efforts have focused on the reliable collection of traces and their statistical interpretation. Display of packet traces was restricted to a textual representation of the raw headers. Our prototype environment interprets the trace as a whole. It identifies conversations across protocol layers, simulates the services offered by lower layers, and hides the lower layer implementation detail from the representation of higher layer conversations. Our prototype offers over a dozen different types of diagrams for showing protocol interactions and uses linked highlighting to show the relationships between the objects in different diagrams.