Abstract

While a number of User-Level Protocols have been developed to reduce the gap between the performance capabilities of the physical network and the performance actually available, applications that have already been developed on kernel based protocols such as TCP have largely been ignored. There is a need to make these existing TCP applications take advantage of the modern user-level protocols such as EMP or VIA which feature both low-latency and high bandwidth. In this paper, we have designed, implemented and evaluated a scheme to support such applications written using the sockets API to run over EMP without any changes to the application itself. Using this scheme, we are able to achieve a latency of 28.5 s for the Datagram sockets and 37 s for Data Streaming sockets compared to a latency of 120 s obtained by TCP for 4-byte messages. This scheme attains a peak bandwidth of around 840 Mbps. Both the latency and the throughput numbers are close to those achievable by EMP. The ftp application shows twice as much benefit on our sockets interface while the web server application shows up to six times performance enhancement as compared to TCP. To the best of our knowledge, this is the first such design and implementation for Gigabit Ethernet.

Citations