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Less -than-Best-Effort Service for Community Wireless Networks: Challenges at Three Layers

Less -than-Best-Effort Service for Community Wireless Networks: Challenges at Three Layers. GAIA meeting, 89 th IETF Meeting 6. 3. 2014. Michael Welzl michawe@ifi.uio.no. Context: the LCDNet vision. From http://publicaccesswifi.org/the-research/paws-approach /. Layer 2 LBE.

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Less -than-Best-Effort Service for Community Wireless Networks: Challenges at Three Layers

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  1. Less-than-Best-Effort Service for Community Wireless Networks:Challenges at Three Layers GAIA meeting, 89th IETF Meeting 6. 3. 2014 Michael Welzl michawe@ifi.uio.no

  2. Context: the LCDNet vision From http://publicaccesswifi.org/the-research/paws-approach/

  3. Layer 2 LBE Insideunder control Outsidenot under control download upload • Can control: • Both ways: PHY rates, PCF? 802.11e QoS? • Download: RA algorithm, DCF parameters like CW

  4. RA alg. impact From: NaeemKhademi, Michael Welzl, Stein Gjessing: "Experimental Evaluation of TCP Performance in Multi-rate 802.11 WLANs”,IEEE WoWMoM2012.

  5. Layer 3 LBE • Shortest path routing is THE routing method • This overloads the shortest path • If there are multiple paths, LBE traffic could take a detour  • Tools exist: e.g. MPLS TE, ECMP… but typically still shortest paths used • multi topology (MT) routing, meant for IP fast reroute, could be a good fit • Small packets could be costly (power consumption) • May want to aggregate + tunnel them (TCMTF)

  6. Layer 4 LBE • End systems: LEDBAT isn’t great • Much more stuff exists • LBE != LBE… • Routers / AP / Modem:AQM can differentiate (early mark/drop)Queue scheduling can differentiate (CBQ etc) From: David Ros, Michael Welzl: "Assessing LEDBAT's Delay Impact", IEEE Communications Letters 17(5), pp. 1044-1047, 2013.

  7. Conclusion • LEDBAT isn’t enough, it’s a larger story • Research needed

  8. Thank you!Questions?

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