P-AQM: low-delay max-min fairness streaming of scalable real-time CBR and VBR media
Arne Lie · Internet, Multimedia Systems and Applications · 2008
The increase in Internet streaming media deployment and consumption has created a network stability challenge. The reason is that in overload situations, such sources continue submitting packets at an unmodified rate. The elastic applications using the TCP protocol will back-off and receive a throughput below their fair rate. The DCCP/TFRC congestion control mechanism is one possible remedy. However, due to its steady packet rate requirement, the end-to-end delay constraints of conversational real-time media like VoIP and videoconferencing can be ruined by the TFRC transmit buffer and router queue backlog. In this paper the P-AQM alternative is presented. P-AQM routers provide more accurate media traffic load information than RED routers, to ensure high link utilization yet low queue backlog. The paper gives the theoretical stability criteria of P-AQM with explicit congestion feedback (ECF) and explicit rate feedback (ERF). Elaborative ns-2 simulations compare scenarios with a mix of MPEG-4 VBR video and TCP traffic, demonstrating P-AQM robustness and performance. The ECF and ERF max-min fairness is explained and compared to TFRC using both CBR and VBR traffic in a GFC-2 network scenario.