| 摘要: | 近年來網際網路的普遍與無線概念興起，除了行動電話之外，人們也希望網際網路的使用可以無線化。在沒有網路線的地方上網，甚至是在移動的過程中上網。因此，IETF（Internet Engineering Task Force）在1996提出了一個繞徑通訊協定 Mobile IP，利用一個固定IP和一個暫時IP來達成無線節點（Mobile Node）在不同網域（domain）之間的移動。但這個方法有著先天的障礙，導致可移動無線設備（Mobile Node）在不同Agent間進行換手時，有大量封包遺失，無線設備因而失去連線。近年來各類的研究致力於減少封包遺失、減少換手（註冊）所需時間、和提出新的換手方式以期望達成無縫連接。這些方法雖然已經可以有效的改善Mobile IP，但都是以理想化的拓普為依據，但理想中的拓普並非總是存在於現實環境中。本論文同樣以改善換手延遲為目標，提出「在Agent中增加一個記錄鄰近Agent的功能」，以達成無縫連接。從評估中可發現，本方法表現與其他方法一樣的品質和效能，即使是在訊號較差的網路拓普中。
The concepts of “wireless” and “mobility” were greatly emphasized in recent years. Users desired for using Internet wirelessly and during in motion, just as the use of mobile phone.
Therefore in 1996, IETF（Internet Engineering Task Force）proposed“Mobile IP”, a routing protocol. However, this scheme has congenital problem: When the mobile node hands off between different agents, plenty of packets might be lost, also, the mobile node might be disconnected.
For the solution to this problem, many recent studies has focused on reducing packet loss, minimizing handoff latency or register latency, as well as designing new handoff schemes to make seamless connection.
Although their findings can improve Mobile IP to a certain extent, those methods employed all rely on “ideal topology”, which can barely exist in reality.
This study aims to improve handoff latency, and proposes “adding the recording feature to every agent, so as the information of neighbor agent could be kept”, hence reaches the goal of “a seamless connection”.
According to the simulation result, our scheme can perform as satisfactory outcomes as other schemes, even in tougher topology. |
