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A Proxy-Based Integrated Cache Consistency and Mobility Management Scheme for Mobile IP Systems

This paper presents a novel scheme for improving mobile client-server applications by maintaining cache consistency and managing mobility in mobile IP systems. It focuses on minimizing access costs and enhancing response times while ensuring service continuity during disconnections. The proposed approach utilizes a proxy-based infrastructure that enables mobile hosts to cache data locally and receive invalidation messages for outdated data. Performance analysis reveals an optimal service area size to reduce overall network traffic, with dynamic adaptability for mobile hosts during their operations. Future research directions include exploring further applications of this scheme and optimizing data transmission strategies.

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A Proxy-Based Integrated Cache Consistency and Mobility Management Scheme for Mobile IP Systems

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  1. A Proxy-Based Integrated Cache Consistency and Mobility Management Scheme for Mobile IP Systems Weiping He, Ing-Ray Chen,and Baoshan Gu Department of Computer Science, Virginia Tech Presented by: Jing (Julia) Xu Apr 11, 2007

  2. Outline • Introduction • System Infrastructure • Cache Consistency • Mobility Management • Performance Analysis: SPN • Experiment Results • Conclusion and Future Work

  3. Introduction • Support mobile client-server applications. • Query dynamic data • Reduce access cost • Improve response time

  4. Introduction (Cont’d) • Challenge: Maintain service continuity with disconnection tolerance. • Disconnection: • Voluntary: connection cost, power consumption. • Involuntary: handoff, wireless link failure. • Service continuity: be able to reuse valid previous data when mobile host (MH) reconnects.

  5. System Infrastructure

  6. Cache Consistency • Overview: • MH can cache data objects locally. • Proxy-based cache: invalidation message. • Up-to-date data in MHCache reduce query traffic and cost. ProxyCache disconnect reconnect MHCache query data invalidation

  7. Mobility Management • To further reduce the network traffic: mobility management by the proxy. • The proxy also serves as the Gateway Foreign Agent (GFA) to maintain the location information of the MH. • When the MH moves across a subnet boundary within the service (GFA) area, it obtains a new care of address (CoA). The proxy is informed of CoA change, but not HA or CNs. • When MH moves across a service (GFA) area, a new GFA becomes proxy and obtains ProxyCache. HA and CNs are informed.

  8. A Trade-off • A large service area: • The proxy will not move often. • The query and cache invalidation cost is high because of the larger distance. • A small service area: • The proxy moves often: • moving proxy cache • informing HA and CNs • The query and cache invalidation cost are lower because of the shorter distance. • Therefore an optimal service area size exists.

  9. Performance Analysis • A performance model based on Stochastic Petri Nets. • Objective: to derive an equation to calculate the overall network traffic cost as a function of the number of subnets covered in a service area. • The MH can determine the dynamic optimal service area size at runtime.

  10. Performance Analysis (Cont’d) • Xs: # of subnets crossed by the MH since the MH enters a new service area • Compute the optimal number of subnets by varying K.

  11. Performance Analysis (Cont’d) K: subnet crossings F(k): number of hops :one-hop communication delay per packet in the wired network : ratio of the communication delay in the wireless to the wired : average distance between proxy and HA : average distance between proxy and a CN N: # of CNs the MH engages nCT: # of packets during a proxy transfer • Transition rates: • Moving =  • Wake2Sleep = ww • Sleep2Wake = ws • MovingProxy = • MH2Proxy = • InquiryProxy =

  12. Performance Analysis (Cont’d) K: subnet crossings F(k): number of hops :one-hop communication delay per packet in the wired network : ratio of the communication delay in the wireless to the wired : average distance between proxy and HA : average distance between proxy and a CN N: # of CNs the MH engages nCT: # of packets during a proxy transfer nD: # of packets to hold a data object • Cost functions: • a • Ci,query = • Ci,mobility= • Ci,invalidation =

  13. Experiment Results There exists an optimal proxy service area size Kopt

  14. Experiments (Cont’d) Kopt exists for all q, i

  15. Experiments (Cont’d) Kopt increases as  increases

  16. Experiments (Cont’d) Kopt decreases as iincreases

  17. Experiments (Cont’d)

  18. Experiments (Cont’d)

  19. Experiments (Cont’d)

  20. Experiments (Cont’d)

  21. Experiments (Cont’d)

  22. Conclusion and Future Work • This scheme allows MH to dynamically determine the best service area size to minimize the overall network traffic generated. • Per MH savings can have significant impacts on all mobile users over a long time period. • Future work: • To investigate applications to which this scheme can apply. • To investigate conditions under which it’s more beneficial for CN to send data instead of invalidation.

  23. Thank you! Questions?

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