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Efficient QoS Support for Optical Burst Switched Networks

Efficient QoS Support for Optical Burst Switched Networks. Pascal Acquaah Prof. H. Anthony Chan Department of Electrical Engineering University of Cape Town. Outline. Introduction and Burst Assembly in OBS QoS Issues in OBS Performance parameters in OBS Previous QoS proposals

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Efficient QoS Support for Optical Burst Switched Networks

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  1. Efficient QoS Support for Optical Burst Switched Networks Pascal Acquaah Prof. H. Anthony Chan Department of Electrical Engineering University of Cape Town

  2. Outline • Introduction and Burst Assembly in OBS • QoS Issues in OBS • Performance parameters in OBS • Previous QoS proposals • Emission and Discard Priority (EDP) scheme • Burst Assembly with EDP scheme • Optimizing Deflection Routing with EDP scheme • Simulation Setup and Simulation Results • Conclusion

  3. Introduction and Burst Assembly in OBS O-O-O CIRCUIT SWITCHING BURST SWITCHING O-O-O/O-E-O PACKET SWITCHING O-E-O O-O-O = All Optical Switching O-E-O = Optical – Electronic – Optical Switching

  4. Introduction and Burst Assembly in OBS Edge Router Egress Node Input Traffic Output Traffic Core Router Ingress Node DWDM Link Input Traffic

  5. Introduction and Burst Assembly in OBS

  6. QoS Issues in OBS • Burst Loss Rate is high • Need for Highly Effective Contention Resolution • Lack of QoS support in the Core Network • Further Service Differentiation required in core network • Lack of practical and simple methods to provide QoS • Certain proposals to resolve contention are too complex to implement and may hinder network performance

  7. QoS Issues in OBS

  8. Performance Parameters in OBS • Throughput (Mbps) • Throughput = (Bytes Received * 8) / 106 • End-to-End Delay (ms) • Tdelay = Tassembly + Toffset + Tprop + Tdisassembly + Tswitch • Tdisassemblyand Tswitch are negligible • Burst Loss Rate • P (burst loss) = 1 – (Burst Recv / Burst Sent) • Goodput • Ratio of packets that reach destination within their delay requirements

  9. Previous QoS proposals • Relative QoS based Solutions • Performance of the network is not guaranteed in quantitative terms • High priority burst loss < low priority burst loss. All based on traffic load • Easy implementation • Absolute QoS based Solutions • Performance of the network is guaranteed in quantitative terms (worst case scenario) • Hard guarantee offers expected level of performance • Complex implementation

  10. Emission and Discard Priority (EDP) Scheme • We introduce the concept of Emission and Discard Priority (EDP) to provide QoS in the OBS network • Emission Priority • Provides Static QoS at the edge • Based on delay tolerance of packets • Discard Priority • Extended service differentiation in the core • Provides Dynamic QoS in the core • Based delay tolerance and loss sensitivity of packets

  11. Burst Assembly with the EDP scheme Offset Payload EP = Emission Priority EP DP BL DC RI Offset DP = Discard Priority BL = Burst Length Burst Header Packet DC = Burst Data channel RI = Routing Information

  12. Burst Assembly with EDP scheme Traffic Category Applications Emission Priority Discard Priority Network Control Critical alarms 2 0 Critical OAM, Routing, Billing 1 3 Interactive VoIP 0 Interactive Gaming Video Conferencing 1 Responsive Streaming Video, Audio 1 2 Client/Server Transactions 3 Timely Email, non-critical OAM 0 3 Best Effort 4

  13. Optimizing Deflection Routing with EDP scheme

  14. Optimizing Deflection Routing with EDP scheme

  15. Performance Objectives • Improve Goodput of deflection routing in the OBS network • Increase throughput • Meet delay requirements • Eliminate unnecessary deflections • Validate the use of deflection routing in OBS

  16. Simulation Setup • Simulation tools • Ns2 Simulator • OBS-0.9a module • Assumptions • No Wavelength Conversion • JET used as reservation scheme • LAUC-VF used for scheduling • Uniform distribution of delay tolerance • Aggregated Pareto traffic sources • Variable-timer based assembly

  17. Network Topology Edge Router Core Router

  18. Simulation Setup

  19. Simulation Results

  20. Simulation Results

  21. Simulation Results

  22. Simulation Results

  23. Simulation Results

  24. Conclusion • We implemented an EDP scheme for simple QoS support in OBS • Deflection with EDP scheme improved the goodput of deflection routing • Deflection with EDP scheme outperformed normal deflection at high loads • High throughput was maintained while meeting delay requirements • Deflection routing with the EDP scheme is suitable to support wavelength conversion for contention resolution in OBS networks

  25. Thank you Questions

  26. Simulation Results

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