SIMULATION ANALYSIS OF ADMISSION CONTROL USING ECN PROBING

Abstract

The traditional approach to implement admission control uses a signaling protocol to establish reservations at all routers along the path. While providing excellent quality-of-service, this approach has limited scalability because it requires routers to keep per-flow state and to process per-flow reservation messages. In an attempt to implement admission control without these scalability problems, recently several schemes have been proposed for various forms of endpoint admission control. In these designs, the hosts (the endpoints) probe the network to detect the level of congestion; the host admits the flow only if the detected level of congestion is sufficiently low. The modest performance degradation between traditional router-based admission control and endpoint admission control suggests that a real-time service based on endpoint probing may be viable. It can be considered that the explicit congestion notification (ECN) as an alternate mechanism (instead of losses) for signaling congestion and show that ECN marking levels can be designed to nearly eliminate losses in the network by choosing the marking level independently for each node in the network. While the ECN marking level at each node may depend on the number of flows through the node, the appropriate marking level can be estimated using only aggregate flow measurements, i.e., per-flow measurements are not required. In this dissertation, we evaluate the performance of the ECN mechanism for the implementation of probing for connection acceptance control by simulation. And we compare the performance of ECN mechanisms with the previous algorithms for the implementation of probing. And from the simulation results, we show that ECN mechanism is better than the previous algorithms for admission control. Also, we modify the mechanism for efficient admission control by setting dynamic threshold value for rejection of calls for the connection establishment.