當行動節點在轉換網域時所經歷的換手時期有兩個非常重要的議題，分別是探討如何減低封包遺失以及降低中斷接收封包的時間。快速換手技術（fast handover）則是因應這樣的需求提出的方法，利用緩衝器的設置，成功地降低了封包遺失的現象，另外在換手期間有二個重要的延遲時期，第二層的換手延遲以及第三層的換手延遲，其中第三層的換手延遲包含了移動偵測延遲、重複位址偵測延遲以及註冊延遲。快速換手技術提到了利用第二層的鏈結層呼叫機制（L2 trigger）的方法降低移動偵測延遲以及利用緩衝器及隧道技術降低註冊延遲，快速換手技術雖有這些優點但換手期間封包產生失序（out-of-order）的問題卻仍存在。而本論文則是利用上述快速換手技術的優勢並加上巧妙運用隨撥位址的特性來隱藏在換手期間所感受到的重複位址偵測延遲，並且利用緩衝器的設置及傳送方式等設定技巧改善了封包失序的問題，使得可更臻一步增進換手時期的效能。

There are two critical issues involved as a mobile node moving across two different network sub-domains. One of them is to minimize the possible packet loss and the other is to shorten the handover time. Fast handover is a remedy to these problems. It minimizes the packet loss by making use of buffers, and speed up the handover procedure by L2 triggering. There are two components contributing to the handover delay, namely L2 handover delay and L3 handover delay. The L3 handover delay consists of movement detection delay, duplicate address detection delay, as well as registration delay. With fast handover, the movement detection delay can be lowered by using L2 trigger, and the registration delay can be decreased by buffering and tunneling. However, the problem of out-of-order packets is still in its existence. A novel handover scheme incorporating the anycast technology is developed and presented in this thesis. With refined buffer control scheme and the switching between unicast and anycast addressing, the handover performance can be greatly improved by the proposed approach.

第一章 簡介 1
1.1 前言 1
1.2研究動機 1
1.3論文架構 2
第二章 發展背景與相關研究 3
2.1 Mobile IP相關名詞介紹 3
2.2 Mobile IP的運作流程 4
2.3 Handover 各階段延遲之分析 5
2.4 Anycast 理論介紹 6
2.5 Fast handover相關名詞介紹 9
2.6 Fast handover之方法介紹 9
2.7 Fast handover之運作流程 10
第三章 利用anycast機制縮短DAD所造成handover延遲時間之方法研究 15
3.1架構介紹 15
3.2 運作流程 16
第四章 模擬與分析 20
4.1 環境設定 20
4.2 數據分析 22
4.2.1 Handover Delay 22
4.2.2 Packet Loss 28
4.2.3 Out-of-order 29
第五章 結論 34
參考文獻 36

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