Probabilistic delay guarantees using delay distribution measurement

Carriers increasingly differentiate their wide-area connectivity offerings by means of customized services, such as virtual private networks (VPN) with Quality of Service (QoS) guarantees, or QVPNs. The key challenge faced by carriers is to maximize the number of QVPNs admitted by exploiting the statistical multiplexing nature of input traffic. While existing measurement-based admission control algorithms utilize statistical multiplexing along the bandwidth dimension, they do not satisfactorily exploit statistical multiplexing along the delay dimension to guarantee distinct per-QVPN delay bounds. This paper presents Delay Distribution Measurement (DDM) based admission control algorithm, the first measurement-based approach that effectively exploits statistical multiplexing along the delay dimension. In other words, DDM exploits the well known fact that the actual delay experienced by most packets of a QVPN is usually far smaller than its worst-case delay bound requirement since multiple QVPNs rarely send traffic bursts at the same time. Additionally, DDM supports QVPNs with distinct probabilistic delay guarantees -- QVPNs that can tolerate more delay violations can reserve fewer resource than those that tolerate less, even though they require the same delay bound. A comprehensive performance evaluation using Voice over IP traces shows that, when compared to deterministic admission control, DDM can potentially increase the number of admitted QVPNs (and link utilization) by up to a factor of 3.0 even when the delay violation probability is as small as 10^-5.