Out of my way - evaluating Low Extra Delay Background Transport in an ADSL access network

The most common broadband access technology today is the (Asymmetric) Digital Subscriber Line (A)DSL. As the name implies, ADSL allocates the bandwidth of upstream and downstream asymmetrically, significantly favoring the downstream direction. Popular applications that serve content over these networks in the upstream direction, such as peer-to-peer (P2P) applications, efficiently utilize the comparably small uplink capacity but potentially disturb inelastic traffic (e.g. voice or games) with an intolerable delay penalty. Effectively, this can render these applications useless. In order to solve this problem, a new delay-based congestion control for this type of P2P background traffic has been proposed. It attempts to utilize the full upstream capacity in the absence of other traffic, otherwise yields to that traffic. This paper describes an implementation and analysis of this new congestion control algorithm in a realistic DSL laboratory setup using a production Multiservice Access Node (MSAN). Using a variety of DSL modems and settings, this worse-than-best-effort transport protocol is further compared to alternative means solving the same problem.