Recent Trends in TCP Packet-Level Characteristics
Paper in proceedings, 2011
Up-to-date TCP trafﬁc characteristics are essential for research and development of protocols and applications.
This paper presents recent trends observed in 70 measurements on backbone links from 2006 and 2009. First, we provide general characteristics such as packet size distributions and TCP option usage. We conﬁrm previous observations such as the dominance of TCP as transport and higher utilization of TCP options. Next, we look at out-of-sequence (OOS) TCP segments. OOS segments often have negative effects on TCP performance, and therefore require special consideration. While the total fraction of OOS segments is stable in our measurements, we observe a signiﬁcant decrease in OOS due to packet reordering (from 22.5% to 5.2% of all OOS segments). We verify that this development is a general trend in our measurements and not caused by single hosts/networks or special temporal events. Our ﬁndings are surprising as many researchers previously have speculated in an increased amount of reordering.