The Internet is once again suffering from its own success. The massive increase in presented load has left many large users with insufficient bandwidth to support their applications. This problem is exacerbated by the lack of performance measures by which by which users can compare IP providers.
We have focused on one particular metric, bulk transfer capacity, and a tool, "TReno," which can function as a basis for a formal bulk transfer metric. Bulk transfer capacity requires a very clean network, and has other properties that make it an important gauge of network performance. We introduce our tool, TReno, and describe its relation to current TCP implementations. Our research with TReno led us to key observations about TCP behavior and influenced details of the new specifications for the TCP Selective acknowledgment (SACK) option. Currently TReno does not precisely estimate TCP's performance in the Internet. As SACK is deployed, and the research community reaches consensus regarding its proper behavior, TReno and state-of-the-art TCP will converge to identical performance and behavior.
The IP Provider Metrics subcommittee of the IETF is developing standardized formal metrics for providers. There is a substantial amount of work to be completed in the areas of measurement procedures and statistics before TReno can become a standardized metric. Our goal is for the TReno development effort and the IPPM standards efforts to converge.
TReno will maximize its potential as a metric if it also functions well as a diagnostic. If a long multi-provider path between two users is not performing as well as desired, it would be extremely valuable to use TReno to measure the path hop-by-hop or provider-by-provider to localize the problem.
As this research, development and standardization progress, we will update online documentation.