- 學位論文
應用於車輛隨意網路之階層式IP配送機制
Hierarchical IP Distribution Mechanism for VANET
摘要
車輛隨意網路的特色即為節點具有高移動速度，路由也不容易維護，並且在車輛欲擷取資訊或連接上網際網路之前，必須先取得IP位址，然而由於車輛的高移動速度之特性，再加上一般在市區中，眾多的車輛向同一部DHCP server要求IP位址的激烈競爭，每部車輛的IP位址組態成功機率將會大幅地降低。 為了達到在車輛隨意網路中快速IP位址組態的目的，並且避免配送重覆的IP位址，本論文提出「階層式IP配送機制」來解決上述的問題。於本研究中，佈署多部DHCP server於市區重要入口與熱點附近，再加上每部DHCP server之間的階層式關係，如此可增加在市區中IP位址分配的效率。並且將DHCP server全都連接到中央一部負責IP位址同步機制的server以避免重覆配送的IP位址，同時再透過由車輛所作的定期回報機制，未用的IP位址也可立即收回，不需等到IP位址的租約時間到期。 本研究以五項評估因子來評估本策略的效能，分別為最高流量分配率、平均分配率、總合組態時間、平均組態時間以及回收率等，並設定不同的交通流量來進行模擬，經由模擬結果可得知，本研究所提出的IP配送機制優於其他作者所提出之策略。
並列摘要
Vehicular Ad Hoc Network (VANET) is characterized by high speed, unstable routing, and the IP addresses must be obtained by vehicles proceeds the Internet. But a low probability of successful IP address configuration for each vehicle exists because of high speed moving and the DHCP with heavy load in the urban due to only one DHCP server employed. Hierarchical IP Distribution (HID) is proposed to solve the aforementioned problems. Some DHCP servers are deployed in the entrances to the urban and near the hotspots. A hierarchical relationship is coming to complete efficiency of IP assignment synchronization. Furthermore, all DHCP servers are connected to one central server for synchronizing IP address. Hence, system could avoid assigning duplicate IP addresses. Besides, the invalid IP addresses can be timely recycled by the periodical report mechanism without considering the lease. The simulation results showed that the strategy HID we proposed outperforms other researches on IP assignment for VANET.