1. High-Availability Network Architectures (HAVANA): High-Availability Network Architectures (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) 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 2 Pre-Cross-Connection: A Design Constraint 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 2 6 4 8 7 1 11 3 4 5 5 9 12 1 10 x3 x2 x5

3. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 3 Outline Architectures Project Overview Methods and Results Conclusions

4. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 4 p-Cycles Straddling span On-cycle span

5. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 5 Failure Independent Path Protecting p-Cycles Straddling path On-cycle path

6. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 7 DSP (Demand-Wise Shared Protection) Understanding DSP: It is essentially 1:N APS over N+1 disjoint routes between end nodes

8. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 8 Outline Architectures Project Overview Methods and Results Conclusions

9. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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 1.Basic architecture design (capacity for single span failure restorability) 2.Dual failure analysis of basic designs 3.Wavelength assignment: feasibility and methods 4.Optical path length constraints: analysis and enhancement Outputs 1.A set of “best feasible” network designs 2.Theoretical insights into architectural properties 3.Design methods and insights

10. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 10 Outline Architectures Project Overview Methods and Results –Basic architecture design Conclusions

11. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 11 “TestSet0” Network

12. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 14 Outline Architectures Project Overview Methods and Results –Basic architecture design –Dual failures Conclusions

15. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 15 Dual Failures: Network Intelligence The response to a first failure cannot change as a result of a second failure; failure responses are independent 1 2 2 1 2 paths restored1 path restored

16. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 16 Results: Dual Failures DSP: ~85% PXTs and p-cycles: ~66% FIPP p-cycles: ~50% 100% …of all failed paths restored over all dual failure scenarios

17. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 17 Outline Architectures Project Overview Methods and Results –Basic architecture design –Dual failures –Wavelength assignment Conclusions

18. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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 Wavelength conversion required for break-in Different wavelengths for 2 different working paths

19. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 20 Outline Architectures Project Overview Methods and Results –Basic architecture design –Dual failures –Wavelength assignment –Optical path lengths Conclusions

21. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 22 Outline Architectures Project Overview Methods and Results Conclusions

23. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 23 Conclusions Dual Failure Restorability Wavelength Assignment Optical Reach Cost of Design p-Cycles FIPP p-Cycles, PXTs DSP Best Worst DSP PXTs, p-Cycles FIPP p-Cycles PXTs FIPP p-Cycles DSP, p-Cycles DSP p-Cycles FIPP p-Cycles, PXTs Architecture Scorecard:

24. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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): High-Availability Network Architectures (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) 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 27 Project HAVANA: Ongoing Work 1.Node Failure restorability analysis (and enhanced design) 2.Detailed minimum-cost mapping of designs into nodal equipment models 3.Costs associated with design for 100% node failure restorability 4.Implications / feasibility of “same wavelength” protection options in each architecture 5.Finding a good heuristic for FIPP p-Cycle design. 6.Design for 100% R2 and/or to support multi-QoP classes involving an ultra high availability (R2=1) priority service.

28. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 28 p-Trees / p-Cycles: Computationally Distinct p-CyclesSpan p-Trees PXTs/FIPP p- Cycles Path p-Trees 100s or 1,000s of structures 10,000s or 100,000s of structures Model Input Size Model Complexity Unified span- protecting structure model Unified path- protecting structure model

29. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 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. HAVANA July 9, 2007 Confidential to TRLabs and Nokia-Siemens Networks 31 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 Too long?