The Failure of TCP in High-Performance Computational Grids

Distributed computational grids depend on TCP to ensure reliable end-to-end communication between nodes across the wide-area network (WAN). Unfortunately, TCP performance can be abysmal even when buffers on the end hosts are manually optimized. Recent studies blame the self-similar nature of aggregate network traffic for TCP’s poor performance because such traffic is not readily amenable to statistical multiplexing in the Internet, and hence computational grids. In this paper, we identify a source of self-similarity previously ignored, a source that is readily controllable - TCP. Via an experimental study, we examine the effects of the TCP stack on network traffic using different implementations of TCP. We show that even when aggregate application traffic ought to smooth out as more applications’ traffic are multiplexed, TCP induces burstiness into the aggregate traffic load, thus adversely impacting network performance. Furthermore, our results indicate that TCP performance will worsen as WAN speeds continue to increase.