이동 네트워크 환경에서 제한된 프리픽스 위임과 연쇄 등록을 이용한 경로 최적화 = Route Optimization in Mobile Network Environment with Limited Prefix Delegation and Chain Registration

다국어 초록 (Multilingual Abstract)

Recently, wireless network environments have became popular in campus and in downtowns.
We can see that ‘ubiquitous society’ coming soon in the near future: people will move freely with various mobile devices connected to the Internet. Vehicles with network facility will carry those people and other network-enabled vehicles everywhere.
Wireless and mobile access to the Internet is the key technology for the coming ubiquitous society.
Nowadays, we can see many devices which is keeping contact to the Internet while moving their location. And there appear mobile access network services such as HSDPA/ HSUPA(High Speed Downlink/Uplink Packet Access) or WIBRO(Wireless Broad band, IEEE 802.16e). These two services for mobile access network are currently running in Korea, and they are supporting high speed movement of mobile devices. The network layer protocols for supporting host mobility are important as much as the mobile access networks. The Mobile IPv4 and the Mobile IPv6 support mobility of hosts, so that hosts can keep network layer connection while moving their location.
In the near future, as the mobile access networks become utility for everyday life, there will be hundreds of thousands or more of mobile nodes change their locations simultaneously and, in a city, mobile networks will be common place. In order to support the mobility of networks, IETF nemo(network mobility) WG has developed ‘Network Mobility (NEMO) Basic Support Protocol’(NEMOv6 hearafter) by extending Mobile IPv6. Recently, IETF mip4 WG is working on ‘Network Mobility (NEMO) Extensions for Mobile IPv4’(NEMOv4 hereafter) to support IPv4 network mobility by extending Mobile IPv4. With NEMOv6 and NEMOv4, networks as well as hosts can freely change their points of attachment to the Internet, while nodes within networks preserving their on-going communication sessions.
Theses protocols, however, do not provide optimal routing path of data packets, which leads to other problems like packet delay and loss. When mobile networks are nested, the problem becomes serious because of bi-directional tunnels created between mobile routers and their home agents. The nesting of mobile networks will be common in the mobility environment, since lots of networks as well as hosts will change their locations freely. For example, people with personal area network(PAN) ride into a bus with their own mobile network, and buses move into a car-ferry with their own mobile network. Therefore, route optimization of mobile network is major issue to be solved in network mobility research area.
This dissertation proposes a route optimization solution based on ‘Limited Prefix Delegation’(LPD) mechanism for NEMOv6. This solution is an extension to the NEMOv6 by making some modification on mobile router’s function. And it shows that this mechanism achieves optimal route in any situation by considering all network configurations specified in the document ‘Network Mobility Route Optimization Problem Statement’.
This mechanism creates only one tunnel from the mobile router which is right above a communicating node directly to the correspondent node, even in the nested mobile networks.
We already have many route optimization solutions for NEMOv6. But currently, there is no solution for NEMOv4. Because IPv6 transition will take several years, NEMOv4 and NEMOv6 will co-exist for years. So, we have to get solution for NEMOv4.
This dissertation also proposes a route optimization solution for NEMOv4 based on
‘Chain Registration’ mechanism. This solution is an extension to the NEMOv4 by making some modifications on mobile router’s function. And it shows that this mechanism achieves optimal route in any situation by considering all network configurations specified in the document ‘Network Mobility Route Optimization Problem Statement’. Even in the nested network, this solution creates only one double tunnel: the inner one is between the mobile router right above the mobile node and its home agent; the outer one is between the foreign agent to home agent of the mobile router.
The rest of the paper is organized as follows. Section 2 describes related researches.
Section 3 describes the route optimization problems of NEMOv6 and NEMOv4 in nested mobile networks. Section 4 describes route optimization solution based on Limited Prefix Delegation and Chain Registration mechanism. Section 5 presents a comprehensive analysis of routes taken by these mechanism and shows that the routes are optimal for any possible network configuration and also presents simulation results. And conclusions are in Section 6.

목차 (Table of Contents)

• 제1장 서론 = 1
• 제2장 관련 연구 = 4
• 2.1 Mobile IPv4 = 4
• 2.2 Mobile IPv6 = 9
• 2.3 NEMOv6 = 13
• 2.4 NEMOv4 = 17
• 제3장 문제점과 제안된 방법 = 20
• 3.1 현재의 문제점 = 20
• 3.1.1 최적화 되지 않은 경로로 인한 문제점 = 21
• 3.1.2 최적화 되지 않은 경로의 예 = 26
• 3.1.3 통신이 불가능해지는 경우의 예 = 34
• 3.2 경로 최적화 방법의 범위 = 37
• 3.2.1 경로 최적화의 이점 = 37
• 3.2.2 네트워크 이동성 경로 최적화 방법의 시나리오들 = 39
• 3.2.3 경로 최적화 때문에 발생하는 문제점 = 43
• 3.2.4 경로 최적화 해결 방법의 범위 = 45
• 3.3 제안된 다른 기술 = 54
• 3.3.1 ORC: Optimized Route Cache Protocol = 54
• 3.3.2 RRH: Reverse Routing Header = 56
• 3.3.3 TLMR: Top Level Mobile Router = 58
• 3.3.4 ARO: Access Router Option = 61
• 3.3.5 PCH: Path Control Header = 63
• 3.3.6 MoRaRo: Mobile Router-Assisted Route Optimization = 64
• 3.3.7 RO-PD: RO-Prefix Delegation = 66
• 제4장 경로 최적화 아키텍처 설계 = 68
• 4.1 RO-LPD: NEMOv6를 위한 제한된 프리픽스 위임 기법 = 68
• 4.1.1 RO-LPD: Limited Prefix Delegation = 70
• 4.1.2 바인딩 갱신 절차 = 76
• 4.1.3 이동 라우터에서의 캡슐화 절차 = 80
• 4.1.4 라우팅 헤더 처리 = 83
• 4.2 RO-CR: NEMOv4를 위한 연쇄 등록 기법 = 87
• 4.2.1 이동 라우터에서 등록 요청 = 88
• 4.2.2 이동 라우터에서 데이터 패킷의 처리 = 90
• 제5장 성능 분석 = 95
• 5.1 데이터 패킷의 전송 경로 분석 = 95
• 5.1.1 RO-LPD: NEMOv6를 위한 제한된 프리픽스 위임 기법 = 95
• 5.1.2 RO-CR: NEMOv4를 위한 연쇄 등록 기법 = 105
• 5.1.3 배치 상황에서 특별한 경우 = 110
• 5.2 수학적 분석 모델 = 117
• 5.3 수학적 분석 결과 = 125
• 5.3.1 RO-LPD: NEMOv6를 위한 제한된 프리픽스 위임 기법 = 125
• 5.3.2 RO-CR: NEMOv4를 위한 연쇄 등록 기법 = 143
• 5.4 시뮬레이션 평가 = 149
• 제6장 결론 = 152
• 참고문헌 = 154