| Summary: | 碩士 === 國立交通大學 === 資訊科學系 === 89 === Clustered architecture provides a promising way to build a scalable, reliable, and high-performance WAP gateway. However, it requires an efficient load balancing mechanism for assigning a request to a selected gateway of the cluster, which can offer the best service. In addition, unpredictable connection time and nonuniformity of the incoming load from different mobile clients in the WAP model are big obstacles to load balancing among real gateways. In this thesis, we propose a load balancing strategy that has the following features: (1) estimating the potential load of real gateways with low
computation and no communication overhead, (2) asynchronous alarm sent when the utilization of a real gateway exceeds a critical threshold, and (3) WAP-awareness. We also propose a scalable WAP gateway (SWG) that consists of a {\it WAP dispatcher} and a {\it cluster of real gateways}. The WAP dispatcher is a front-end distributor with our load balancing strategy. To prevent the WAP dispatcher from becoming a bottleneck, the WAP dispatcher distributes mobile clients' requests in kernel space and does not process outgoing
gateway-to-client responses. Experiment results show that our SWG has better load balancing performance, throughput, and delay compared to the LVS and the Kannel gateway.
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