Proactively controlling round-trip time variation and packet drops using SmoothTCP-q

摘要

Packet drops are the primary means of signalling congestion in TCP. However, packet drops have a great impact on round-trip time (RTT) variation of TCP applications. A different and more proactive approach is used by SmoothTCP-q, where ICMP-SQ messages are sent directly to the sender every time a threshold is reached in the queue size of the router. In this mechanism, SmoothTCP-q tries to avoid packet drops since it is not necessary to overload the router queue to discover the network bandwidth as Standard TCP does. As a result, SmoothTCP-q generally presents better quality of service characteristics in terms of RTT variation and packet drops when compared to TCP. In this paper we describe SmoothTCP-q and illustrate its main characteristics related to this proactive property.