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

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. Outline. Introduction System Infrastructure Cache Consistency

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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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