Stateless admission control for QoS provisioning for VoIP in a DiffServ domain

The IETF has defined two primary approaches for providing QoS aware services in the Internet: Integrated Services (IntServ) and Differentiated Services (DiffServ). The stateful IntServ features per-connection control, but lacks scalability. The stateless Diffserv possesses excellent scaling properties, but lacks a, standardized admission control (AC) scheme and degradation of service can occur during overload. Following RFC 2990, we recently proposed ail AC scheme, Gauge & Cate Reservation with Independent Probing (GRIP), which can provide strict QoS guarantees by means of stateless DiffServ-compliant procedures. We previously assumed only that traffic offered to the network is regulated by dual leaky bucket (DLB) systems having known parameters; no other assumption was made about the traffic. When we compared the voice-call carrying capacity afforded by GRIP to that of a reference system having an ideal, stateful AC policy, we found that the QoS guarantees were gained at the expense of seriously reduced call carrying capacity with respect to the Reference System (stateful). In this paper, we present a specific implementation of GRIP, optimized for a voice over IP scenario. We derive an AC decision criterion based on the standard statistical characterization of voice and then evaluate the performance of the AC policy via simulation and compare the results to the Reference System as before. We find that the required QoS criteria are satisfied while resource utilization, as evidenced by call carrying capacity, is very close to the performance of the Reference System.