Achieving faster access to satellite link bandwidth

Abstract

TCP with Van Jacobson congestion control (VJCC) is known to have poor performance over large bandwidth-delay product paths. Long delay paths, in particular, can display very poor behavior with VJCC slowly probing to acquire available capacity. TCP performance enhancing proxies (PEPs) constitute one mechanism for ameliorating poor VJCC end-to-end performance by splitting TCP connections around a long-delay link or network, and using alternate congestion control dynamics across the troublesome portion. Previous congestion control techniques for use over satellite links have typically constituted either tweaks to the Van Jacobson algorithms, Vegas-style congestion control or disabling congestion control altogether in favor of a manual send-rate. This paper analyzes results from measurements of a new congestion control mechanism, the explicit Control protocol or XCP, between PEPs with a simulated geosynchronous satellite link in the path. We show that connections using an XCP PEP acquire their share of expensive satellite bandwidth up to 70 times faster than end-to-end TCP with VJCC.