無線網路環境可分為有基礎架構(infrastructure)的無線網路與無基礎架構的特殊網路(ad-hoc network)兩大類。在ad-hoc網路中，行動機(mobile host)通常需藉由其他的行動機才能連接到主幹網路。這種系統我們稱之為多階(multihop)網路系統。本篇論文主要是延伸並修正Mobile IP，使之適用於多階無線區域網路。同時我們亦針對所提的方法，實作一多階無線區域網路雛型系統，使得行動機能夠在不同的網域中漫遊。此外本系統與原先的Mobile IP系統是互通的(transparent)，即在單階(single hop)環境下亦能正常運作。

Wireless networks can be divided into infrastructure networks and ad-hoc networks. In an ad-hoc local area network, mobile hosts can access Internet via intermediate mobile hosts. This kind of local area network (LAN) is called as multihop wireless LANs. In this thesis, we extend and modify the Mobile IP protocol to support multihop wireless LANs such that the mobile host can roam among different subnets. In addition, we also implement this new Mobile IP under Window environment. Our proposed system is transparent with the original Mobile IP, i.e., it can also work in the signal hop wireless LAN.

Abstract (in Chinese)i
Abstract (in English)ii
Acknowledgementsiii
Contentsiv
List of Tablesvii
List of Figuresviii
1. Introduction1
1.1 Problem Description.......................................................................................3
1.1.1 Routing Mechanism of Internet Protocol.....................................................3
1.1.2 Other Problems of Mobile IP in Ad-hoc Networks......................................4
1.2 Related Work.................................................................................................6
2. Mobile IP and Routing Algorithms...................................................................8
2.1 Mobile IP........................................................................................................8
2.1.1 Terminology................................................................................................8
2.1.2 Overview of Mobile IP System....................................................................10
2.1.3 Agent Discovery..........................................................................................12
2.1.4 Registration..................................................................................................13
2.1.5 Tunnel..........................................................................................................14
2.2 Routing Algorithms.........................................................................................16
2.2.1 Table-Driven Routing...................................................................................16
2.2.2 On-Demand Routing....................................................................................18
2.2.3 Comparisons........................................................................................................20
2.2.4 Interoperability with Mobile IP..............................................................................21
3. Mobile IP for Multihop Wireless LANs........................................................................23
3.1 Overview of Our System..............................................................................23
3.2 Issues........................................................................................................25
3.2.1 Routing Problem........................................................................................................25
3.2.2 Construction of Hierarchical Tree..............................................................................26
3.3 System Architecture...................................................................................................28
3.3.1 Mechanism of Sending Packets..............................................................................29
3.3.2 Mechanism of Receiving Packets..............................................................................30
3.3.3 Registration Procedure..............................................................................31
3.3.4 Communication........................................................................................................32
4. Implementation........................................................................................................34
4.1 System Setup........................................................................................................34
4.1.1 Environment........................................................................................................34
4.1.2 System Parameters........................................................................................................36
4.2 System Elements........................................................................................................37
4.2.1 Home Agent........................................................................................................38
4.2.2 Foreign Agent........................................................................................................39
4.2.3 Advertiser........................................................................................................41
4.2.4 Mobile Client........................................................................................................41
4.3 The Problems in the Implementation..............................................................................44
4.3.1 Foreign Agent Creates "direct route"..............................................................................45
4.3.2 Relay Registration Request Message..............................................................................45
4.3.3 Bridge............................................................................................................................45
4.3.4 Modify Agent Advertisement Message..........................................................................46
5. Conclustion........................................................................................................................47
Bibliography...........................................................................................................................48

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[2] C. E. Perkins ed. "Ipv4 Mobility Support",RFC 2002,Oct. 1996.
[3] http://www.ietf.org
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[23] D. E. Deering ed. "ICMP Router Dicsovery Messages", RFC 1256, Sept. 1991.
[24] J. B. Postel ed. "Internet Control Message Protocol",RFC 792, Sept. 1981.
[25] J. Postel. "User Datagram Protocol," RFC 768,Aug.1980.
[26] D. L. Rivest, "The MD5 Message-Digital Algorithm," RFC 1321,Apr. 1992.
[27] R. Dorms, "Dynamic Host Configuration Protocol",RFC 1541,Oct. 1993.
[28] W. Simpson,ed. "Point-to-Point Protocol,"RFC 1332. July 1994.
[29] D. C. Plummer, "An Ethernet Address Resolution Protocol: Or Converting Network,Protocol Address to 48bits Ethernet Address for Transmission on Ethernet Hardware," RFC 826,Nov. 1982.
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[31] G. Malkin, "RIP Version 2 Carrying Additional Information," RFC 1723, 1994.
[32] J. Moy, "OSPF Version 2," RFC 1583, 1994.
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