This project is funded under the National Science Foundation's (NSF) Small Business Innovation Research (SBIR) program, which is designed to provide an opportunity for small business, particularly the small high technology firm, to participate in NSF research. Phase I of the SBIR program serves as a filter to select promising proposals and determine if the firm can do high quality research. Phase II is the principal research project. Phase III is the conversion of the NSF-funded research into commercial applications and technological innovation supported by follow-on private venture capital or other non-federal financing. This is a Phase II project to develop a prototype expert protocol analyzer, which is an expert system for analyzing problems arising between two different implementations of a communications protocol. The expert system tool will incorporate knowledge of the protocol specifications as well as troubleshooting expertise of skilled protocol analysts. The prototype tool will be developed to analyze the entire DoD protocol stack running on an Ethernet LAN and will use an existing LAN monitor for capture and transmission of protocol data on the LAN. The expert protocol analyzer could be combined with an existing commercially available LAN monitor to provide additional analytic capabilities for the monitor. The enhanced tool could be used for troubleshooting protocol problems on operational networks, assisting in the installation of new protocols, and testing for protocol conformance to specification.