| Summary: | 碩士 === 元智大學 === 資訊工程學系 === 91 === Finding an optimal multi-constraint QoS path in a computer network is a NP hard problem. In the past, many researchers have proposed solutions, such as heuristic searching, limited hop flooding, selective probing and parallel probing, to find a feasible multi-constraint QoS routing path with reduced routing overhead. These solutions use basic monolithic routing protocol, i.e., they are built from scratch and are independent of existing routing protocols. However, this is neither practical nor necessary. In this thesis, we propose two new QoS routing protocols, shortest path aware routing algorithm (SAR) and next-hop path aware routing algorithm (NAR), based on a programmable router model, such as P1520. In this routing architecture, a new routing service can be built on existing routing services, such as OSPF, and using routing table as an interface. We use an N-hop flooding protocol as our basic routing information exchange protocol. Based on which, an OSPF routing protocol is built and provides default routing service. New routing services can be built upon the services of N-hop flooding, OSPF, and some other routing protocols. In our flooding algorithm, we limit flooding overhead by hop count N, finite response time (timeout), and receive-once policy. In order to reduce excessive resources reservation, we employ Two-Pass resource reservation scheme in our routing protocol. We compare the performance of our algorithms with traditional flooding algorithm and shortest path routing by simulation. The simulation results show that the proposed algorithms SAR and NAR have good performance than traditional flooding algorithm and the shortest path routing. The results also confirm that simple QoS routing services can be easily implemented to obtain good value-added services on layered routing architecture.
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