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A. Grue, W. D. Grover, J. Doucette, B. Forst, D. Onguetou, D. Baloukov TRLabs

H igh- Ava ilability N etwork A rchitectures (HAVANA): Comparative Study of Fully Pre-Cross-Connected Protection Architectures for Transparent Optical Networks Contact: grover@trlabs.ca. A. Grue, W. D. Grover, J. Doucette, B. Forst, D. Onguetou, D. Baloukov TRLabs (Network Systems Group)

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A. Grue, W. D. Grover, J. Doucette, B. Forst, D. Onguetou, D. Baloukov TRLabs

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  1. High-Availability Network Architectures (HAVANA):Comparative Study of Fully Pre-Cross-Connected Protection Architectures for Transparent Optical NetworksContact: grover@trlabs.ca A. Grue, W. D. Grover, J. Doucette, B. Forst, D. Onguetou, D. Baloukov TRLabs (Network Systems Group) 7th Floor, 9107 – 116 Street Edmonton, Alberta, Canada T6G 2V4 M. Clouqueur, D. Schupke Nokia Siemens Networks (Network Control-Plane and Transport) Otto-Hahn-Ring 6 81730 Munich, Germany

  2. Non-Pre-Cross-Connected Shared “pool” of spare capacity Backup paths cross-connected at failure time Examples: SBPP, span-restorable mesh Pre-Cross-Connected Cross-connections for backup paths formed in advance of failure Resulting chains of pre-cross-connected capacity coalesce into protection “structures” Examples: BLSR, p-cycles -1 -1 -1 -1 -1 Pre-Cross-Connection: A Design Constraint x2 1 2 5 8 5 11 9 12 7 6 4 10 3 1 4 x5 x3

  3. Outline • Architectures • Project Overview • Methods and Results • Conclusions

  4. p-Cycles Straddling span On-cycle span

  5. Failure Independent Path Protecting p-Cycles Straddling path On-cycle path

  6. PXTs (Pre-Cross-Connected Trails) Understanding PXTs: Behave like FIPP cycles, only the structures are not closed As a consequence, they are not able to provide two protection paths for failed working paths

  7. DSP (Demand-Wise Shared Protection) Understanding DSP: It is essentially 1:N APS over N+1 disjoint routes between end nodes

  8. Outline • Architectures • Project Overview • Methods and Results • Conclusions

  9. Project HAVANA Outline/Objectives • Objective: To characterize and compare many different pre-cross-connected protection architectures on a single network, under real-world constraints to network intelligence and flexibility • Project Phases • Basic architecture design (capacity for single span failure restorability) • Dual failure analysis of basic designs • Wavelength assignment: feasibility and methods • Optical path length constraints: analysis and enhancement • Outputs • A set of “best feasible” network designs • Theoretical insights into architectural properties • Design methods and insights

  10. Outline • Architectures • Project Overview • Methods and Results • Basic architecture design • Conclusions

  11. “TestSet0” Network

  12. Working Routing: Constraints • Models for FIPP, PXTs, and p-cycles are SCP (spare capacity placement) only; working routing is static • Both FIPP and PXTs require a working routing such that at least one path, disjoint from the working path, exists between the end nodes

  13. Results: Spare Capacity Redundancy • p-Cycles are the most capacity efficient • DSP has capacity efficiencies just slightly lower than that of 1+1 APS

  14. Outline • Architectures • Project Overview • Methods and Results • Basic architecture design • Dual failures • Conclusions

  15. 1 2 2 1 2 paths restored 1 path restored Dual Failures: Network Intelligence • The response to a first failure cannot change as a result of a second failure; failure responses are independent

  16. Results: Dual Failures …of all failed paths restored over all dual failure scenarios 100% DSP: ~85% PXTs and p-cycles: ~66% FIPP p-cycles: ~50%

  17. Outline • Architectures • Project Overview • Methods and Results • Basic architecture design • Dual failures • Wavelength assignment • Conclusions

  18. Wavelength Assignment in p-Cycles • p-Cycles require either wavelength conversion or at least 2 fibres on every span in order to support wavelength continuity Different wavelengths for 2 different working paths Wavelength conversion required for break-in

  19. Results: Wavelength Assignment • Wavelengths are allocated to the network in bands of 20 • 40-wavelength (2 bands) assignment found for all architectures • 20-wavelength (1 band) assignments found for: • PXTs (modified SCP model) • FIPP p-cycles (JCP model necessary) • Not found for: • DSP (impossible) • p-cycles (perhaps possible using JCP?)

  20. Outline • Architectures • Project Overview • Methods and Results • Basic architecture design • Dual failures • Wavelength assignment • Optical path lengths • Conclusions

  21. Results: Optical Path Lengths • Only DSP design satisfied reach constraints with the original design • PXTs and FIPP p-cycle designs easily found by modifying the pre-processing step • Compliant p-cycle design found by using a new ILP model altogether

  22. Outline • Architectures • Project Overview • Methods and Results • Conclusions

  23. Conclusions • Architecture Scorecard: Cost of Design Dual Failure Restorability Wavelength Assignment Optical Reach PXTs p-Cycles DSP DSP Best FIPP p-Cycles, PXTs FIPP p-Cycles, PXTs PXTs, p-Cycles FIPP p-Cycles DSP, p-Cycles p-Cycles Worst DSP FIPP p-Cycles

  24. To Find Out More… • References on PXTs, FIPP p-Cycles, DSP (listed in paper) • A. Kodian, W.D. Grover, “Failure Independent Path-Protecting p-Cycles: Efficient and Simple Fully Pre-connected Optical-path Protection,” IEEE Journal of Lightwave Technology, vol. 23, no.10, October 2005. • T. Y. Chow, F. Chudak, A. M. Ffrench. “Fast Optical Layer Mesh Protection Using Pre-Cross-Connected Trails,” IEEE/ACM Trans. Networking, vol. 12, no. 3, pp. 539-547, June 2004. • Koster, A. Zymolka, M. Jager, R. Hulsermann, “Demand-wise Shared Protection for Meshed Optical Networks,” Journal of Network and Systems Management, vol. 13, no. 1, pp. 35-55, March 2005. • A. Grue, W.D. Grover, “Characterization of pre-cross-connected trails for optical mesh network protection,” OSA Journal of Optical Networking, May 2006, pp.493-508

  25. High-Availability Network Architectures (HAVANA):Comparative Study of Fully Pre-Cross-Connected Protection Architectures for Transparent Optical NetworksContact: grover@trlabs.ca A. Grue, W. D. Grover, J. Doucette, B. Forst, D. Onguetou, D. Baloukov TRLabs (Network Systems Group) 7th Floor, 9107 – 116 Street Edmonton, Alberta, Canada T6G 2V4 M. Clouqueur, D. Schupke Nokia Siemens Networks (Network Control-Plane and Transport) Otto-Hahn-Ring 6 81730 Munich, Germany

  26. Some Insights • DSP: • - Why isn't it more efficient than it is ? (Turns out almost identical to 1+1 APS) • - Amenability to exact design with ILP (design ease) • PXTs: • High design and conceptual complexity • Good flexibility for wavelength assignment, optical path length constraints • p-Cycles • Surprise that plain p-Cycles still have the best spare capacity efficiency • Not inherently end-to-end path-protecting • Optical Reach design control developed • FIPP p-Cycles • Offer a simple end-to-end “protected path tunnel” operating paradigm • Exact ILP design possible, heuristics under development

  27. Project HAVANA: Ongoing Work • Node Failure restorability analysis (and enhanced design) • Detailed minimum-cost mapping of designs into nodal equipment models • Costs associated with design for 100% node failure restorability • Implications / feasibility of “same wavelength” protection options in each architecture • Finding a good heuristic for FIPP p-Cycle design. • Design for 100% R2 and/or to support multi-QoP classes involving an ultra high availability (R2=1) priority service.

  28. Model Complexity Unified span-protecting structure model Unified path-protecting structure model Model Input Size 100s or 1,000s of structures 10,000s or 100,000s of structures p-Trees / p-Cycles: Computationally Distinct

  29. The “Z” Case in FIPP p-Cycle Design • Protection paths are pre-connected, but the protection path to be used will depend on the failure scenario • For the purpose of this study, the network was deemed not intelligent enough to handle this degree of failure dependency

  30. The “Z” Case in FIPP p-Cycle Design • Protection paths are pre-connected, but the protection path to be used will depend on the failure scenario • For the purpose of this study, the network was deemed not intelligent enough to handle this degree of failure dependency

  31. Too long? Optical Path Lengths for p-Cycles • In a path-protecting architecture, protection paths are completely substituted for working paths during failure, meaning that the lengths of the restored state paths are not in question • In a span-protecting architecture (p-Cycles, span p-Trees), protection paths are only substituted for the failed span, which may be used by many working paths with different lengths

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