Load-tolerant differentiation with active queue management

Current work in the IETF aims at providing service differentiation on the I nternet. One proposal is to provide loss differentiation by assigning level s of drop precedence to IP packets. In this paper, we evaluate the active q ueue management (AOM) mechanisms RED In and Out (RIO) and Weighted RED (WRE D) in providing levels of drop precedence under different loads. For low dr op precedence traffic, RIO and WRED can be configured to offer sheltering ( i.e., low drop precedence traffic is protected fi om losses caused by highe r drop precedence traffic). However, if traffic control fails or is inaccur ate, such configurations can cause starvation of traffic at high drop prece dence levels. Configuring WRED to instead over relative differentiation can eliminate the risk of starvation. However, WRED cannot, without reconfigur ation, both over sheltering when low drop precedence traffic is properly co ntrolled and avoid starvation at overload of low drop precedence traffic. T o achieve this, we propose a new AQM mechanism, WRED with Threshold (WRT). The benefit of WRT is that, without reconfiguration, it offers sheltering w hen low drop precedence traffic is properly controlled and relative differe ntiation otherwise. We present simulations showing that WRT has these prope rties.