End-to-end detection of compression of traffic flows by intermediaries

Routers or nodes on the Internet sometimes apply link-layer or IP-level compression on traffic flows with no knowledge of the end-hosts. If the end-host applications are aware of the compression already provided by an intermediary, they can save time and resources by not applying compression themselves. The benefits from these savings are even greater in mobile applications. We present a probing technique to detect the compression of traffic flows by intermediaries. Our technique is non-intrusive and robust to cross traffic. It is entirely end-to-end, requiring neither changes to nor information from intermediate nodes. We present two different but similar approaches based on how cooperative the end-hosts are. Our proposed technique only uses packet inter-arrival times for detection. It does not require synchronized clocks at the sender and receiver. Simulations and Internet experiments were used to evaluate our approach. Our findings demonstrate an accurate detection of compression applied to traffic flows by intermediaries.