A Multi-objective QoS Mechanism for Web Applications: Improved EFXCP

The research of QoS is concerned with multiple QoS requirements (multi-QR): queue delay, delay jitter and guaranteed throughput etc. As different QoS requirements have different attributes, it is hard to ensure multi-QR in one QoS mechanism. A common method to ensure multi-QR is normalizing multi-QR into one value range by a utility function and then finding the optimal solution of the utility function. However, although multi-QR are considered in such QoS mechanisms, in fact, no concrete QoS requirement can been strictly ensured, which may be embarrassing because web application usually requires one or more concrete QoS requirements to be satisfied strictly. Therefore, it is significant to design a real multi-objective QoS mechanism to satisfy different QoS requirements of various web applications. Our previous works proposed an efficient and fair explicit congestion control protocol (EFXCP) which can achieve excellent performance in terms of high link utilization, low queue delay, low delay jitter, etc. Because different web applications have different throughput requirements, to further satisfy throughput requirements of web applications, we extend EFXCP in this paper to implement an improved EFXCP (IEFXCP). Firstly, ToS field in IP header is utilized to classify different web applications, and then the relative fair bandwidth allocation is proposed between different types of web applications to preferentially ensure throughput requirements of high prior web applications. Therefore, IEFXCP can simultaneously satisfy multi-QR: queue delay, delay jitter and guaranteed throughput. The performance of IEFXCP is validated by extensive NS2 simulations over a wide range of network scenarios, the results show that IEFXCP is a real multi-objective QoS mechanism.