EVALUATING INTERNET END-TO-END PERFORMANCE - OVERVIEW OF TEST METHODOLOGY AND RESULTS

Objective: An evaluation of Internet end-to-end performance was conduc ted for the purpose of better understanding the overall performance of Internet pathways typical of those used to access information in Nati onal Library of Medicine (NLM) databases and, by extension, other Inte rnet-based biomedical information resources. Design: The evaluation us ed a three-level test strategy: 1) user testing to collect empirical d ata on Internet performance as perceived by users when accessing NLM W eb-based databases, 2) technical testing to analyze the Internet paths between the NLM and the user's desktop computer terminal, and 3) tech nical testing between the NLM and the World Wide Web (''Web'') server computer at the user's institution to help characterize the relative p erformance of Internet pathways. Measurements: Time to download the fr ont pages of NLM Web sites and conduct standardized searches of NLM da tabases, data transmission capacity between NLM and remote locations ( known as the bulk transfer capacity [BTC]), ''ping'' round-trip time a s an indication of the latency of the network pathways, and the networ k routing of the data transmissions (number and sequencing of hops). R esults: Based on 347 user tests spread over 16 locations, the median t ime per location to download the main NLM home page ranged from 2 to 5 9 seconds, and 1 to 24 seconds for the other NLM Web sites tested. The median time to conduct standardized searches and get search results r anged from 2 to 14 seconds for PubMed and 4 to 18 seconds for Internet Grateful Med. The overall problem rate was about 1 percent; that is, on the average, users experienced a problem once every 100 test measur ements. The user terminal tests at five locations and Web host tests a t 13 locations provided profiles of ETC, RTT, and network routing for both dial-up and fixed Internet connections. Conclusion: The evaluatio n framework provided a profile of typical Internet performance and ins ights into network performance and time-of-day/day-of-week variability . This profile should serve as a frame of reference to help identify a nd diagnose connectivity problems and should contribute to the evolvin g concept of Internet quality of service.