| Summary: | 碩士 === 國立臺北教育大學 === 資訊科學系碩士班 === 95 === In Mobile IP protocol, the Home Agents (HAs) is responsible for recording the location information and forwarding the datagram for the roamed Mobile Nodes (MNs). Besides, it also enables the MNs to maintain continuous data connectivity without interruption while changing locations. If a single HA fails, the MNs served by it are not able to accept the datagram. Therefore, in some researches, the mechanisms with multiple Mobility Agents (MAs) are proposed for solving the fault-tolerant problem. However, most existing fault-tolerant protocols for the mobility agents will increase the time of registration process and need much system resource. To cope with this problem, in this thesis, we use the set system of quorum size . In a mobility system with redundant HAs, we propose an efficient cyclic-quorum-based fault-tolerant protocol and group all HAs into N quorums in a network with N HAs imposing logical circular structure. In the proposed protocol, every HA has backup quorums and divides the network that it manages into equal parts. According to the home address of the MN, each HA finds out the backup quorum in the network segment and stores the mobility bindings of the MN in backup HAs. When a HA crashes, the system will select the HA with minimum load from each backup quorum for taking over the bindings of the faulty HA respectively. In comparison with previous related works, our experimental results show that the proposed fault-tolerant protocol has many advantages: better system load balance, less latency for registration process, less system resource requirements, and no extra hardware cost.
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