Why Is This Web Page Coming Up so Slow? Investigating the Loss of SYN Packets

摘要

Before the first valid calculation of the round trip time for a connection, TCP sets an initial value for the retransmission timeout to 3 seconds which, in the case of the first packets getting lost, introduces a long delay. For short transfers, like web traffic, this could have a significant influence on the performance. We performed measurements to investigate how often this happens. As our measurements show, control packets (SYN and SYN/ACK packets) do get lost and delays of 3 seconds or even more (further timeouts) occur. By means of a simple example implementation, we indicate that this problem could be solved.