Cascaded TCP: Applying Pipelining to TCP for Efficient Communication over Wide-Area Networks

Abstract—The bandwidth utilization in traditional TCP pro-tocols (e.g., TCP New Reno) suffers over high-latency and high-bandwidth links due to the inherent characteristics of TCP con-gestion control. Conventional methods of improving throughput cannot be applied per se for streaming applications. The challenge is exacerbated by “big data ” applications such as with the Long Wavelength Array data that is generated at a rate of up to 4 terabytes per hour. To improve bandwidth utilization, we introduce layer-4 re-lay(s) that enable the pipelining of TCP connections. That is, a traditional end-to-end connection is split into independent streams, each with shorter latencies, that are then concatenated (or cascaded) together to form an equivalent end-to-end TCP connection. This addresses the root cause by decreasing the latency over which the congestion-control protocol operates. To understand when relays are beneficial, we present an analytical model, empirical data and its analyses, to validate our argument and to characterize the impact of latency and available bandwidth on throughput. We also provide insight into how relays may be setup to achieve better bandwidth utilization. Index Terms—bandwidth utilization; throughput; perfor-mance; long-fat networks; pipelining; TCP; wide-area networks I