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Experiments with Less than Best Effort (LBE) Quality of Service on GÉANT

Experiments with Less than Best Effort (LBE) Quality of Service on GÉANT. Tiziana Ferrari. Experimental set-up (cont). Performance without congestion. One-way delay. IPDV. traffic volume: [10, 50] % 2 flows (1 LBE, 1 BE) maximum IPDV (BE): 11 usec sample of 100 consecutive packets

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Experiments with Less than Best Effort (LBE) Quality of Service on GÉANT

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  1. Experiments with Less than Best Effort (LBE) Quality of Service on GÉANT Tiziana Ferrari Experiment with LBE Quality of Service on GÉANT

  2. Experimental set-up (cont) Experiment with LBE Quality of Service on GÉANT

  3. Performance without congestion Experiment with LBE Quality of Service on GÉANT

  4. One-way delay Experiment with LBE Quality of Service on GÉANT

  5. IPDV • traffic volume: [10, 50] % • 2 flows (1 LBE, 1 BE) • maximum IPDV (BE): 11 usec • sample of 100 consecutive packets • IPDV negligible for both LBE and BE Experiment with LBE Quality of Service on GÉANT

  6. Packet reordering • - proportional to packet rate • affecting both LBE and BE • maximum IPDV (BE): 11 usec • sample of 100 consecutive packets • packet reordering due to the M-160 architecture Experiment with LBE Quality of Service on GÉANT

  7. Performance with congestion Experiment with LBE Quality of Service on GÉANT

  8. Packet loss • 3 LBE streams (75% of traffic load), 1 BE stream (25%), plus BE production • traffic • in case of LBE congestion: • no BE packet loss • no IP Premium packet loss (when IP Premium traffic is injected) • only LBE packet loss, proportional to the amount of LBE • traffic injected Experiment with LBE Quality of Service on GÉANT

  9. Throughput • 7 LBE streams, 2 BE streams, 1 IPP stream • load: [50, 100] % • in case of LBE congestion (traffic load: 100% of a STM-16) : • BE and IPP per-flow throughput equals the UDP input rate • only LBE throughput affected by LBE congestion Experiment with LBE Quality of Service on GÉANT

  10. One-way delay • 100 streams, 98 streams DE2 -> IT, 2 streams DE2 -> DE1 (LBE and BE) • LBE: • increase in both average and max one-way delay in case of congestion • max delta (max – min): 1.865 msec • BE: • Slight increse of average and max one-way delay • Max delta (max – min): 0.537 msec Experiment with LBE Quality of Service on GÉANT

  11. One-way delay frequency distributions (LBE) • test duration: 10 sec • time divided in time intervals of 0.1 sec each -> 100 intervals • for each interval, min/avg/max one-way delay is recorded Experiment with LBE Quality of Service on GÉANT

  12. One-way delay frequency distributions (BE) Experiment with LBE Quality of Service on GÉANT

  13. IPDV (LBE) • 2 streams: 1 LBE stream, 1 BE stream (DE2 -> IT) • considerable increase in maximum LBE IPDV • no difference in IPDV frequency distributions with and without congestion • (100 consecutive packets) Experiment with LBE Quality of Service on GÉANT

  14. Packet reordering • BE queue priority = LBE queue priority = high • extremely high percentage of out-of-order packets in case of congestion • percentage is a function of the packet rate of a given stream • it affects both BE and LBE traffic • the configuration of different queue priorities solves the problem of throughput loss • of BE end-to-end TCP streams Experiment with LBE Quality of Service on GÉANT

  15. Conclusions • LBE DSCP transparency on GEANT is possible • Correct isolation of BE traffic from LBE congestion • Negligible impact on BE one-way delay and IPDV • Packet reordering can be greatly reduced so that end-to-end TCP throughput is preserved, by: • assigning a lower weight to the EF queue • Configuring different priorities to the LBE and BE queues • Packet reordering seems to affect TCP best-effort throughput if the parameters are wrong. Experiment with LBE Quality of Service on GÉANT

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