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Integrating Mobile IP with Ad Hoc Networks

Integrating Mobile IP with Ad Hoc Networks. 作者： Yu-Chee Tseng,Chia-Ching Shen(nctu) Wen-Tsuen Chen(nthu) 報告者：王生見. content. 1. Abstract 2. Mobile IP and MANETS Related work in internet computing 3. Network architecture 4. Communication scenarios

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Integrating Mobile IP with Ad Hoc Networks

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  1. Integrating Mobile IP with Ad Hoc Networks 作者：Yu-Chee Tseng,Chia-Ching Shen(nctu) Wen-Tsuen Chen(nthu) 報告者：王生見

  2. content • 1. Abstract • 2. Mobile IP and MANETS • Related work in internet computing • 3. Network architecture • 4. Communication scenarios • 5. Intra-Manet and inter-Manet routing scenarios • 6. Broadcast routing scenario • 7. Integration and implementation • TTL in IP packets • Agent advertisement • Agent solicitation • ARP • Broadcast • Destination address and TTL • Configuration of IEEE 802.11b NICs

  3. Abstract • Ubiquitous computing has added a new feature, mobility, to the world of computing and communications. • Mobile IP and mobile ad-hoc network(MAnet) • Application • Integrating

  4. Mobile IP and Manet Figure1 mobile IP transmission scenario.

  5. Related work in internet computing(1/5) • Mobile IP was originally designed to support macro mobileity • Researchers have developed two other internet protocols • Cellular IP and the handoff-aware wireless access internet infrastructure (Hawaii)

  6. Related work in internet computing(2/5) • Cellular IP • Uses a hierarchical approach to minimize registrations to home agents as a mobile host roaming around. • A foreign agent can provide services to multiple base station. • As long as the same foreign agent’s base stations cover the mobile host, no reregistration is required, thereby significantly reducing handoff delay.

  7. 名詞解釋(home agents and foreign agent) • Home Agent： • 主要是傳遞資訊給從這個Home network離開的Mobile Nodes，並且維護mobile node目前的位置資訊。 • Foreign Agent： • 與Home Agent合作，完整地去傳遞資訊給從home network離開的mobile node。

  8. Related work in internet computing(3/5) • Hawaii protocol • Adopts a domain-based approach in which base stations can be connected as a tree. • It uses specialized path setup schemes that install host-based forwarding entries in specific routers to support intradomain routing. • Unlike cellular IP • Hawaii breaks the gateway-foreign-agent tie and thus is more tolerant to gateway failure, which simplifies gateway design.

  9. Related work in internet computing(4/5) • Other research has addressed using Manet to provide continuous internet access via mobile IP. • This includes extending mobile IP to let mobile hosts use a care-of address even if they are more than one hop away from a foreign agent. • It also resolves the conflict between mobile IP and Manets in managing routing tables.

  10. 名詞解釋(care-of address) • 暫時位址（Care-of Address）： • 一個表示當Mobile Host不在Home Network時，在網路上接點的IP位址。

  11. Related work in internet computing(5/5) • Compared to earlier efforts that focused on only a single Manet • Consider the existence of multiple Manets in same vicinity • With mobile agents and mobile hosts negotiating foreign agents’ service ranges • Improves Manets flexibility and reduces mobile agents’ service overhead

  12. Network architecture Figure2 proposed network architecture.

  13. Communication scenarios • Our proposed network architecture can accommodate several different communication scenarios. • In discussing the possible combinations • We assume that DSDV supports all corresponding Manet routings • Although any proper routing protocol is applicable

  14. 名詞解釋(DSDV)Destination-Sequenced Distance-Vector routing • Destination-Sequenced Distance-Vector Routing • 傳統Bellman-Ford路由選擇演算法所改良而發展出來的，一個以routing table為基礎的通訊協定。 • 每一個行動節點必須儲存一個routing table，其中紀錄所有與該節點可能進行連結的節點及距離(no of hops) • routing table內的每筆紀錄同時也包含了一個sequence number，這是用來判斷是否有些路徑比較老舊，以避免routing table的產生。 • DSDV基本上和網際網路上的Distance-Vector Routing相同，只是多了destination sequence number的紀錄 • 當網路topology變動比較不頻繁時，並不需要將routing table的所有資料進行交換，DSDV在每個節點內再加了一個table，用來記錄其routing table從上次交換至今所更改的部分 • 如果更改很多，就進行全部資料的交換，稱為full dump封包，如果改變很少，就只針對改變部分交換，稱為incremental封包。

  15. Intra-Manet and inter-Manet routing scenarios

  16. Inter-Manet routing scenarios in overlaid Manets

  17. Broadcast routing scenario

  18. Integration and implementation(1/9) System architecture of our implementation.

  19. Integration and implementation(2/9) • TTL in IP packets • Each IP datagram has a TTL field to control its internet lifetime. • Routing inside Manets • Implementation is based on the DSDV protocol. • Each host maintains a forwarding table that lists all available destinations along with the next hop leading to each destination. • Our prototype made some modifications to the DSDV protocol • Because Manets can overlap in our architecture.

  20. Integration and implementation(3/9) • Agent advertisement • Manets multihop nature requires setting the TTL to N and decreasing the value by one for each reboadcast • No rebroadcast is necessary when the TTL is equal to 0

  21. Integration and implementation(4/9) • Agent solicitation • A mobile host can multicast an Agent_Soliciation message to locate a nearby mobile agent. • The original TTL value should be recorded in the packet’s payload so that when the gateway receives the packet. • It can recover its distance to the requesting mobile host.

  22. Integration and implementation(5/9) • ARP • Instead,The host registers the MAC-to IP address mapping when it receives an Agent_Advertisement message. • Our network architecture • Enabling the address resolution protocol in foreign networks to send requests and replies as usual. • Because many nomadic hosts can exist in a Manet • These networks should relay packets of any destination without using a subnetmask.

  23. Integration and implementation(6/9) • Broadcast • When it receives the packet, the gateway decapsulates it and broadcasts it with a TTL equal to N. • To prevent broadcast datagram from looping back to the source host • The broadcast daemon also records broadcast datagram that it has encapsulated recently.

  24. Integration and implementation(7/9) • Destination address and TTL • In view of the fact that the M value that Manets use should be at least as large as the N (N->TTL,M->hop) • We recommend setting M equal to 2N • Which guarantees that intra-Manet communication can always occur directly without encapsulation. • In the worst case, a packet has to travel from a Manet’s boundary to the gateway • In addition, communication between nearby Manets is likely to occur without going through mobile IP • Thus the packet will not undergo encapsulation.

  25. Integration and implementation(8/9) • In our frame work • The network should function correctly, but some routes may not exist even if some hosts are physically neighbors. • Our system is based on Linux Redhat and implements two daemons, DSDVd and MIPd.

  26. Integration and implementation(9/9) • DSDVd • periodically multicasts user datagram protocol packets to help maintain the hosts’ forwarding tables. • System calls write proper entries from the forwarding table into the kernel’s routing table. • MIPd • Uses raw sockets for advertisement, encapsulation, and decapsulation, and it uses normal sockets for registration. • Unix system calls perform proxy ARP. • In addition, the IP forwarding option at each mobile hosts must be turned on.

  27. 報告結束

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