PuNDIT will integrate and enhance several software tools needed by the High Energy Physics (HEP) community to provide an infrastructure for identifying, diagnosing and localizing network problems. In particular, the core of PuNDIT is the Pythia tool that uses perfSONAR data to detect, identify and locate network performance problems. The Pythia algorithms, originally based on one-way latency and packet loss, will be re-implemented incorporating the lessons learned from its first release and augmenting those algorithms with additional metrics from perfSONAR throughput and traceroute measurements.  The PuNDIT infrastructure will build upon other popular open-source tools including smokeping, ESnet's Monitoring and Debugging Dashboard (MaDDash) and the Open Monitoring Distribution (OMD) to provide a user-friendly network diagnosis framework.