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A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment Bruce Zenel

A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment Bruce Zenel. Jupyung Lee CoreLab, KAIST March 18. 2003. Contents. Introduction Architecture PMICP Proxy Server Adaptation through Filter Control Designed and Implemented Filters Evaluation HTTP filter

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A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment Bruce Zenel

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  1. A General Purpose Proxy Filtering Mechanism Applied to the Mobile EnvironmentBruce Zenel Jupyung Lee CoreLab, KAIST March 18. 2003 KAIST EECS Computer Engineering Research Lab

  2. Contents • Introduction • Architecture • PMICP • Proxy Server • Adaptation through Filter Control • Designed and Implemented Filters • Evaluation • HTTP filter • NFS filter • TCP filter • Conclusion & Future Work KAIST EECS Computer Engineering Research Lab

  3. Introduction • Mobile environment • Slower, more costly, less reliable, less secure than WAN, LAN… • Heterogeneity problem : hosts move unpredictably in networks which have different speed, cost, security, loss rate • Proxy improves the mobile environment • Drop / Compress / Delay / Cache data • MPEG / HTTP, NFS / POP / TCP • Act as substitute for mobile client • ICMP ECHO request • Use a different transport protocol(or parameter settings) • Generally… : perform trading off computation for communication * Minimize server/client modification KAIST EECS Computer Engineering Research Lab

  4. Introduction (cont’) • Filter : program downloading & executing on proxy • Often application specific • Dynamically control filter behavior • Contribution of this paper • Propose ‘general purpose proxy filtering mechanism’ applied to the mobile environment • Apply it to the HTTP, NFS, TCP KAIST EECS Computer Engineering Research Lab

  5. Architecture: PMICP • Problem: • All traffic from/to MH must past through a single gateway • But mobile protocol* supports host mobility • Keep track of the location of the MH • Using Mobile Support Routers(MSR) • Solution • New Protocol : PMICP** • Each MH choose Proxy MSR(PMSR) • PMICP guarantees that all traffic from/to MH will pass through PMSR * Proxy filter runs on PMSR * Columbia Mobile IP Protocol ** Proxy Mobile Internetworking Control Protocol KAIST EECS Computer Engineering Research Lab

  6. (Proxy MSR) KAIST EECS Computer Engineering Research Lab

  7. Architecture: Proxy Server • High Level Proxy • Use filter insertion • Low Level Proxy • LLP packet queue is created configured. • It contains matching criterion • If criterion is matched, filter is allows to read/write LLP packet queue * Analogous to socket program KAIST EECS Computer Engineering Research Lab

  8. (Filter Insertion) * Kernel on Proxy & MH may be modified * Server notices no change KAIST EECS Computer Engineering Research Lab

  9. Architecture: Adaptation through Filter Control • Event Registry(ER) • Register in certain events • Change in network bandwidth • Network interface information • Change in MH battery power • MH location • Notified when these events occur KAIST EECS Computer Engineering Research Lab

  10. Designed and Implemented Filters • HTTP: compress header/body of HTTP messages • MPEG: drop intermediate MPEG frames • SMTP: drop all multimedia data • NFS: compress file data • ICMP: provide replies to queries • TCP • Cache unacknowledged TCP to MH • Perform local re-TX when packet loss is detected • arrival of a duplicate ack, local timeout • Not break the end-to-end semantics of TCP • Originally from “Improving TCP/IP Performance over Wireless Networks” KAIST EECS Computer Engineering Research Lab

  11. Evaluation • 10Mbps Ethernet vs. 2Mbps Wavelan vs. 33.3Kbps SLIP • HTTP filter • compress text file using ZLIB or LZO • not compress image file • Primary proxy as compressor, secondary as decompressor • Provide client transparency • NFS filter : compress text/binary files using ZLIB or LZO • TCP filter : use unacknowledged packet caching Server Proxy Gateway Client Client Client KAIST EECS Computer Engineering Research Lab

  12. Performance of HTTP Filter KAIST EECS Computer Engineering Research Lab

  13. Performance of NFS Filter KAIST EECS Computer Engineering Research Lab

  14. Performance of TCP Filter KAIST EECS Computer Engineering Research Lab

  15. Conclusion & Future Work • General Purpose Proxy Mechanism • Author’s future work • End-to-End semantics • High level proxy breaks the end-to-end semantics of TCP • Security • Message security between proxy & MH • Filter code security • Proxy mobility • # proxies • Adapt protocol / application KAIST EECS Computer Engineering Research Lab

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