Performance evaluation of an off-host communications architecture

The Computer Networks Laboratory at the University of Virginia has implemented the SAFENET lightweight protocol suite on the Navy's Desktop Tactical Computer (DTC-2). One of the research questions was whether to embed XTP in the DTC-2's UNIX kernel or run XTP on an attached processor on the DTC-2's VMEbus. Both strategies were implemented and the attached processor approach proved to have somewhat higher performance. The hardware and software system environment is surveyed, the performance achieved at the media access controller (MAC), transport, and user levels is reported, and an analytic model for predicting throughput and latency as a functon of vendor-provided or easily measured system parameters is developed. The authors' conclusions identify both the advantages and performance concerns inherent to off-host protocol execution.