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NOBEL – Paris meeting, February 2005

NOBEL – Paris meeting, February 2005. Telenor (Partner #27) WP 2 Survivability, traffic engineering, techno- and socio-economic studies and evaluations A2.2: Study of traffic engineering concepts for end-to-end broadband services for all. Measurement device.

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NOBEL – Paris meeting, February 2005

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  1. NOBEL – Paris meeting, February 2005 Telenor (Partner #27) WP 2 Survivability, traffic engineering, techno- and socio-economic studies and evaluationsA2.2: Study of traffic engineering concepts for end-to-end broadband services for all NOBEL Paris meeting February 8-10

  2. Measurement device Idea:Real-time resource allocation based on measurements Incoming traffic stream Outgoing, shaped traffic stream Resources allocated as determined from measurements, ex.: output rate R (bandwidth) and buffer Dropped packets Measure load over successive time intervals of length T T is the granularity of the measurements Does not disturb traffic (same traffic characteristics before and after) NOBEL Paris meeting February 8-10

  3. Main questions • If measurements are done at time scale T, and resources are allocated according to measurements, what is the consequence for QoS? • Given an algorithm for how output rate is determined by measured load values; example: rate = observed peak load of last x measurements • Given a certain traffic characteristics • How can we adjust the output rate so that a given QoS requirement is fulfilled? NOBEL Paris meeting February 8-10 See Berlin presentation from Telenor for more detailed description of the questions raised

  4. Results for synthetic traces Synthetic traffic traces: Poisson and Weibull distribution Packet IATs: mean value = 0.13ms Packet lengths are all the same Load = 0.2 Amounts to 155Mbit/s with 500 byte packets NOBEL Paris meeting February 8-10

  5. NOBEL Paris meeting February 8-10

  6. NOBEL Paris meeting February 8-10

  7. Higher variability in traffic implies higher relative amount of extra BW required (fixed T) Lower T gives lower relative amount of extra BW needed because measured peak load is higher NOBEL Paris meeting February 8-10

  8. Results for real traces, UST1 All packet interarrival times scaled down so mean value is the same as for the synthetic traces eases comparison to synthetic Note that all correlations of real trace are kept Packet sizes synthetic, homogeneous size, average load 0.2 eases comparison to synthetic Same offered load, packet size and same interface rate NOBEL Paris meeting February 8-10

  9. Aggregate traffic, subtraces (~stationary) Of interest for further study: the variation of traffic mix throughout a single measurement trace Trace 1: packet numbers 350,000 – 600,000 in UST1. Trace 2: packet numbers 50,000 – 300,000 in UST1. Huge difference in packet loss for the two traces Reason, possible: • Different traffic mix? More Weibull-like than Poisson-like in trace 1 than in trace 2? NOBEL Paris meeting February 8-10

  10. Aggregate traffic, subtraces (~stationary) Increased buffer size implies less packet loss because bursts can be smoothed out NOBEL Paris meeting February 8-10

  11. Comparing TCP and UDP: -Packet loss -Extra BW needed for given QoS requirement NOBEL Paris meeting February 8-10

  12. Conclusions and main observations • Results from synthetic traces seems to indicate that a somewhat coarse observation granularity may be satisfactory in many cases when combined with a long buffer • i.e. non real-time or Poisson-like traffic, less strict packet loss requirement • For a measurement trace, traffic characteristics will change over time due to changing traffic mix • Different traffic streams have rather different characteristics and thus different methods must be developed • Our method applies for traffic streams / sub-aggregates containing traffic with similar characteristics • From the traces we need to filtered out traffic with similar characteristics based on available classification parameters (L4-protocol and portnumbers) • Packet loss when no extra BW is allocated is more severe for UDP that for TCP. • Related to the fact that measured peak load is higher for TCP than for UDP, because TCP traffic is more variable that UDP traffic • Increasing buffer size has larger positive effect for UDP than for TCP NOBEL Paris meeting February 8-10

  13. Plans for 2005 • Filter out traffic streams for which the traffic characteristics is reasonably generally applicable • In aggregate traffic the traffic mixture that accidentally happens to be present determines the overall traffic characteristics • The interesting part is to study effects that are not accidental • Does anyone plan to do filtering and analysis that we can benefit from? • Non-stationarity in measured traces is problematic: • Complicates the effort to distinguish effects due to stationary traffic characteristics from effects due to non-stationarity • Will any partner filter out non-stationary elements? If so, we would like to use the resulting stationary traces in our analysis. • Non-stationary synthetic traces • Underlying trends superpositioned on Poisson / Weibull • Specify true real-time algorithm • Threshold values for when to reallocate resources NOBEL Paris meeting February 8-10

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