Reducing the user perceived delay of interactive TCP connections using a dynamic priority approach

Many interactive applications require continuous user interaction, for example ssh and many web applications. The TCP connections created by these applications are therefore in a class called interactive. When interactive applications suffer from packet loss the packet retransmission time severely increases the user perceived delay. This work introduces a Dynamic Priority RED Queue (DPRQ) algorithm that dynamically changes the priority of queues instead of dropping packets when the queue is overloaded. The algorithm reduces the user perceived delay by reducing packet loss in interactive TCP connections. The DPRQ is compared to an existing Class-Based Queue which incorporates RED (RCBQ) as would typically be used for Assured Forwarding. An analytical model of the DPRQ and RCBQ is presented with both experimental and analytical results. The DPRQ is found by simulation to decrease packet loss by up to eight times and therefore provide a lower user perceived delay even though queuing delay is increased by up to five times.