Packet spreading techniques to avoid bursty traffic in long RTT TCP connections

In all the TCP protocol variants, included the TCP Hybla proposal recently presented by the authors, the segment transmission rate is given by the ratio between the congestion window (cwnd) and the Round Trip Time (RTT). As a result, to provide a high throughput to long RTT connections (e.g. satellite), it is necessary to make use of large cwnds, which, on the other hand, may increase the transmission burstiness, with consequent possible huge overflows at intermediate router queues. An effective countermeasure is “packet spreading” (or, “packet spacing”), which considers the introduction of inter-packet delays to spread packets in time. In the work, the most representative techniques considered in literature are analyzed and compared with a new technique, called “progressive” spacing. Reported results show that packet spreading really allows for a better exploitation of the available satellite bandwidth.