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The Challenge of Challenged Networks

The Challenge of Challenged Networks. S. Keshav University of Waterloo Dharamshala, September 8, 2010. Waterloo?. Where is that?. Home of: RIM/Blackberry Watcom/Sybase Maple OpenText ManuLife. The Challenge of Challenged Networks. S. Keshav University of Waterloo

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The Challenge of Challenged Networks

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  1. The Challenge of Challenged Networks S. Keshav University of Waterloo Dharamshala, September 8, 2010

  2. Waterloo? Where is that?

  3. Home of: RIM/Blackberry Watcom/Sybase Maple OpenText ManuLife

  4. The Challenge of Challenged Networks S. Keshav University of Waterloo Dharamshala, September 8, 2010

  5. A Fundamental Problem • Technology operates in a social, cultural and economic context • Real-world success depends on both the technology and the context • Nearly impossible to determine context in advance • and it may change

  6. Challenged networks • Challenging conditions create unique requirements and also place strong constraints including: • Environmental • Infrastructural • Social • Cultural • Legal • Economic

  7. How to proceed? • Iterative process of design, deployment, and refinement

  8. Context: requirements, constraints, and alternatives Design Redefine requirements and constraints Implement Test Monitor Deploy

  9. Context: the SoftBridge stack People People UI UI Synch Synch Media Media Device Device Network Network Power Power Tucker and Blake, University of the Western Cape, South Africa

  10. Design • Design every layer of the SoftBridge stack, not just the network! • DTN offers alternatives but is not a panacea • Don’t underestimate cellular networks • economies of scale • femtocells

  11. Implement • Challenged networks limit options • avoid lock-in • Don’t build on unproven technology • ‘error 22’ (?) • Build in monitoring

  12. Test • Don’t skimp on testing, painful though it may be • Build test harnesses • Always investigate unexpected results • What you cannot explain is at the heart of new knowledge

  13. Deploy • Always start with a pilot • Feet on the street • Start small

  14. Monitor • Monitor everything • Visualize data graphically • Don’t skimp on analysis • Insist on formal reporting

  15. Refine • Use monitoring data to refine assumptions, constraints, and requirements • Be prepared to throw away the first and second systems • ruthlessness is essential

  16. The rule of three • The first system is too naïve • The second system is too ambitious • The third system is usable

  17. Another rule of three • The first system is too simple • The second system is too complex • The third system is simple in just the right ways Strive to achieve the second simplicity!

  18. Summary so far • Contextualize • Iterate • Simplify

  19. Case study: KioskNet

  20. KioskNet (2005-2008) Trade delay for cost

  21. People UI Synch Media Device Network Power

  22. Experiences • Single-board Linux-based computers are not mass-market • hard to debug and maintain by locals • Vehicular environment is harsh • failure • theft • Difficult to get agreement from transportation providers

  23. VLink (2009) • Addresses problems with KioskNet • Reuses existing Windows and Linux desktops • Software-only solution • No computer in vehicle • No need for buy in from transportation authorities • and MUCH cheaper! • Leverages USB memory sticks (KeyLink) and SMS (SMSLink)

  24. Applications • Email • VSync • keeps two directories in sync

  25. Outcome? • Probably a failure • NGOs do not want unsupported software • SMS/voice communication on mobiles appears adequate • 3G is coming

  26. Case study: TIER/Aravind People UI Synch Media Device Network Power

  27. Conclusions • Designing any successful network is difficult; challenging environments exacerbate this • Contextualize using the SoftBridge stack • Iterate to build at least three solutions • Simplify the system systematically and ruthlessly • Success is not assured

  28. Grad students : S. Liang, A. Seth, N. Ahmed, M. Ghaderi, S. Guo, M.H. Falaki, S. Ur Rahman, E. A. Oliver, U. Ismail, S. Rahbar Graduate interns: R. Luk, Z. Koradia Staff Programmer: D. Kroeker, M. Derakhshani, A. Ganjali Undergrads :  M.Zaharia, P. Darragh,  N. Arora, Y. Yin, G. Salmon, G. Wang, M. Liang, M. Thomas, A. Agarwal,Y. Xu, Y. Hu, S. Dube, R. Sethi, C. Ho,  C. Tan, A. Leong Affiliated Faculty:  T. Brecht (UW), U. Hengartner (UW), S. Prasad  (IIT Delhi), H. Saran (IIT Delhi) Staff support:  G. Chopiak Thank you!

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