A passive approach to detection of traffic shaping

Internet service providers often alter the profile of data traffic, a practice referred to as 'shaping'. This may be done in order to comply with a service contract,or for the provisioning of services with real-time delivery constraints. This means that the effective throughput to the customer is reduced in some way, either for all traffic, or for one or more individual flows. The presence of traffic shaping may be controversial in some circumstances, particularly when certain classes of traffic are shaped (thus altering the traffic profile). The detection of the existence of traffic shaping on a particular connection or flow is desirable, but technically it is a nontrivial problem. This is especially so if the end-user has limited or no knowledge of the outside network conditions. In this paper, we propose a 'blind' traffic shaping detection algorithm, and investigate its effectiveness. The proposed approach is based on order statistics, with limited per-packet computational complexity. This paper describes our novel approach to the detection of traffic shaping, provides several experimental results in different scenarios, and compares the effectiveness of several metrics. Finally, avenues for further developing the algorithm are suggested.