Fun Factor Characterization of User Perceived Quality of Service for Elastic Internet Traffic

Abstract

Classical quality of service (QoS) measures such as packet loss probability, delay or delay variation are available for non-elastic network traffic. However, most of today’s data traffic is transported over the Transmission Control Protocol (TCP) in the Internet, and TCP uses a flow control mechanism to adapt a connection’s hit rate to the resources available in the network in order to get the same “fair share” of bandwidth as the other TCP connections sharing the same bottleneck link. Recent efforts in describing elastic traffic have recalled Processor Sharing models and tried to establish bandwidth related QoS measures such as “delay factors” or “fun factors” to describe the user perceived quality of service for elastic traffic applications. In this paper we discuss possible definitions of fun factors as well as DNS and TCP properties that influence the bit rates achievable with elastic traffic. Measurement results give an indication of the rates occurring in the Internet. They also reveal the delays and success rates to be expected from DNS requests, which can be a major cause of delay in HTTP retrievals.