1. C O R P O R A T E T E C H N O L O G Y Strategies for Enhanced Dual Failure Restorability with Static or Reconfigurable p-Cycle Networks International Conference on Communications (ICC) Paris, France - June 22, 2004 Dominic A. Schupke* Siemens AG, Corporate Technology Otto-Hahn-Ring 6, 81730 Munich, Germany E-mail: Wayne D. Grover, Matthieu Clouqueur TRLabs and University of Alberta 7th Floor, 9107 116 St NW, Edmonton, Alberta, Canada T6G 2V4 E-mail: {grover,clouqueur}@trlabs.ca *Results from work at Technische Universität München and TRLabs

2. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Outline Introduction The p-Cycle Concept p-Cycles and Dual Failures Network Design Results Conclusions

3. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Introduction Preconfigured protection cycles (“p-cycles”): Applicable in many kinds of networks High capacity-efficiency Fast protection switching times For span-protection: 100% restorability against any single span failure Our focus: Provide enhanced or optimized level of dual-failure restorability Static and reconfigurable p-cycles

4. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 The p-Cycle Concept A p-cycle in a mesh network: D A B E C

5. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 The p-Cycle Concept On-cycle link failure: D A B E C

6. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 The p-Cycle Concept Straddling link failure: D A B E C Straddling link Path 1

7. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 The p-Cycle Concept Straddling link failure: D A B E C Path 2

8. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Assumptions on Dual Failures Dual failure scenarios: Assumption: t 1 + t 1,rec. < t 2 p-Cycles: t rec. ~ 50 ms t1t1 t 1 +t 1,rec. t2t2 First (span) failure Recovery from first failure Second failure t 2 +t 2,rec. t 2 +t 2,rep. t 1 +t 1,rep. Recovery from second failure (if possible) Repair of first failure Repair of second failure

9. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Static p-Cycles and Dual Failures D A B E C t1t1

10. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Static p-Cycles and Dual Failures D A B E C  No recovery for B-C from second failure t1t1 t2t2

11. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Static p-Cycles and Dual Failures D A B E C t1t1 p -Cycle A p -Cycle B

12. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Static p-Cycles and Dual Failures D A B E C  Recovery from second failure t1t1 t2t2 p -Cycle A p -Cycle B

13. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Susceptibility Concept p-Cycle susceptible to a dual failure combination: Both failures affect working spans protected by it p-Cycle protects s working spans  Susceptible to s (s-1) failure events Susceptibility s per p-cycle not larger than given σ max Restrict when selecting eligible p-cycles for design Other approach: Failure dispersal concept (see paper)

14. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Reconfigurable p-Cycles and Dual Failures D A B E C t1t1

15. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Reconfigurable p-Cycles and Dual Failures D A B E C t1t1 Vulnerable protection capacity

16. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Reconfigurable p-Cycles and Dual Failures D A B E C t1t1 Vulnerable working capacity

17. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Reconfigurable p-Cycles and Dual Failures D A B E C t1t1 p -Cycle formed - after t 1

18. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Reconfigurable p-Cycles and Dual Failures D A B E C  Recovery from second failure t1t1 t2t2 p -Cycle formed - after t 1 and - before t 2

19. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Network Design Cost-optimal design: Length-weighted utilization of network Single-failure restorability: 100% restorability guaranteed Dual-failure restorability: R(i,j): Restorable fraction of affected working capacity after dual failure of spans i and j R 2 : Average over all dual failure cases

20. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Network Design

21. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 COST239 Case Study Network Hypothetical pan-European optical network of COST239 project Traffic matrix modified to lightpath entries Average nodal degree: d av = 4.7 Three-connected (connected after any dual span failure)

22. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Results for Static p-Cycles 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.5 0.6 0.7 0.8 0.9 1 Dual failure Restorability Additional Relative Spare Capacity Cost Reconfiguration σ max =4 σ max =13 σ max =9 smaller σ max

23. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Results for Reconfigurable p-Cycles 0 0.5 1 1.5 2 2.5 3 Relative Spare Capacity Cost Static Reconfiguration R 2 =100% Vulnerable working capacity protected only Fraction of p-cycles changeable in form Only additional p-cycles 100%5%0%

24. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Conclusions Capacity design methods: Static p-cycles: Improved dual-failure restorability Susceptibility viable approach to control restorability Reconfigurable p-cycles: Complete dual-failure restorability Different operational options Outlook: Reconfigurable p-cycles in networks designed for single-failure restorability only Multiple protection classes

25. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Literature Schupke, D.A.; Grover, W.D.; Clouqueur, M., "Strategies for Enhanced Dual Failure Restorability with Static or Reconfigurable p-Cycle Networks," IEEE International Conference on Communications (ICC), Paris, France, June 20-24, 2004. Schupke, D.A., "An ILP for Optimal p-Cycle Selection without Cycle Enumeration," Eighth Working Conference on Optical Network Design and Modelling (ONDM), Ghent, Belgium, February 2-4, 2004. Schupke, D.A.; Scheffel, M.C.; Grover, W.D.,"Configuration of p-Cycles in WDM Networks with Partial Wavelength Conversion," Photonic Network Communications, Kluwer Academic Publishers, vol. 6, no. 3, pp. 239-252, November 2003. Schupke, D.A.; Jaeger, M.; Huelsermann, R., "Comparison of Resilience Mechanisms for Dynamic Services in Intelligent Optical Networks," Fourth International Workshop on the Design of Reliable Communication Networks (DRCN), Banff, Alberta, Canada, October 19-22, 2003. Schupke, D.A.; Scheffel, M.C.; Grover W.D., "An Efficient Strategy for Wavelength Conversion in WDM p- Cycle Networks," Fourth International Workshop on the Design of Reliable Communication Networks (DRCN), Banff, Alberta, Canada, October 19-22, 2003. Kodian, A.; Grover, W.D.; Slevinsky, J.; Moore, D., "Ring-Mining to p-Cycles as a Target Architecture: Riding Demand Growth into Network Efficiency," to appear in Proceedings of the 19th Annual National Fiber Optics Engineers Conference (NFOEC 2003), Orlando, FL, 7-11 September 2003. Schupke, D.A., "Multiple Failure Survivability in WDM Networks with p-Cycles," Invited Paper, IEEE International Symposium on Circuits and Systems (ISCAS), Bangkok, Thailand, May 25-28, 2003. Shen, G.; Grover, W.D., "Extending the p-Cycle Concept to Path-Segment Protection," Proc. IEEE International Conference on Communications (ICC 2003), Anchorage, AK, USA, May 11-15, 2003, Session ON3. Schupke, D.A., "The Tradeoff Between the Number of Deployed p-Cycles and the Survivability to Dual Fiber Duct Failures," IEEE International Conference on Communications (ICC), Anchorage, AK, USA, May 11-15, 2003.

26. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Literature Grover, W.D. "p-Cycles, Ring-Mesh Hybrids and "Ring-Mining:” Options for New and Evolving Optical Networks," Invited Paper, Proc. Optical Fiber Communications Conference (OFC 2003), Atlanta, March 24- 27, 2003, pp.201-203. Grover, W.D. "Understanding p-Cycles, Enhanced Rings, and Oriented Cycle Covers" (invited paper), 1st Int’l Conference on Optical Communications and Networks (ICOCN’02), Singapore, Nov.11-14, 2002, pp. 305-308. Jaeger, M.; Huelsermann, R.; Schupke, D.A.; Sedlak, R., "Evaluation of Novel Resilience Schemes in Dynamic Optical Transport Networks,“ SPIE Conference Asia-Pacific Optical and Wireless Communications (APOC), Shanghai, China, October 14-18, 2002. Schupke, D.A., "Fast and Efficient WDM Network Protection Using p-Cycles," TransiNet Workshop, Berlin, Germany, October 8, 2002. Grover, W:D.; Doucette, J. E., "Advances in Optical Network Design with p-Cycles: Joint optimization and pre-selection of candidate p-cycles," Proceedings of the IEEE-LEOS Summer Topical Meeting on All Optical Networking, Mont Tremblant, Quebec, July 15-17, 2002. Schupke, D.A., "Fast and Efficient WDM Network Protection Using p-Cycles," Invited Paper, IEEE LEOS Summer Topical Meeting, Mont Tremblant, Canada, July 15-17, 2002. Gruber, C.G.; Schupke, D.A., "Capacity-efficient Planning of Resilient Networks with p-Cycles," Networks 2002, 10th International Telecommunication Network Strategy and Planning Symposium, Munich, Germany, June 23-27, 2002. Grover, W:D.; Doucette, J. E.; Clouqueur, M.; Leung, D.; Stamatelakis, D."New Options and Insights for Survivable Transport Networks," IEEE Communications Magazine, vol.40, no.1, January 2002, pp. 34-41. Schupke, D.A.; Grover, W.D.; Gruber, C.G.; Stamatelakis, D., "p-Cycles: Network Protection with Ring-speed and Mesh-efficiency,“ Invited Talk, 1 st COST270 Workshop on Reliability of Optical Networks, Systems and Components, Dubendorf, Switzerland, December 12-13, 2001.

27. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Literature Schupke, D.A.; Autenrieth, A.; Fischer, T., "Survivability of Multiple Fiber Duct Failures," Third International Workshop on the Design of Reliable Communication Networks (DRCN), Budapest, Hungary, October 7-10, 2001. Grover, W.D.; Stamatelakis, D., “Bridging the ring-mesh dichotomy with p-cycles,” Second International Workshop on the Design of Reliable Communication Networks (DRCN), Munich, Germany, April 9 - 12, 2000. Grover, W.D.; Stamatelakis, D., "IP Layer Restoration and Network Planning Based on Virtual Protection Cycles," IEEE JSAC Special Issue on Protocols and Architectures for Next Generation Optical WDM Networks, vol.18, no.10, October, 2000, pp. 1938 - 1949. Grover, W.D.; Stamatelakis, D., "Theoretical Underpinnings for the Efficiency of Restorable Networks Using Pre-configured Cycles ("p-cycles")," IEEE Transactions on Communications, vol.48, no.8, August 2000, pp. 1262-1265. Grover, W.D.; Stamatelakis, D., "Rapid Restoration of Internet Protocol Networks using Pre-configured Protection Cycles," Proc. 3rd Can. Conf. On Broadband Research (CCBR'99), Nov. 7-9, Ottawa, 1999, pp.33- 44. Grover, W.D.; Stamatelakis, D., "Cycle-oriented distributed pre-configuration: ring-like speed with mesh-like capacity for self-planning network restoration," in Proc. IEEE International Conf. Commun. (ICC '98), Atlanta, June 8-11, 1998, pp. 537-543.

28. C O R P O R A T E T E C H N O L O G Y © TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22 Network Design Assumptions: Dual-failure scenario: Subsequent failures at t 1 and t 2 (with t 2 < t 1 + t repair ) Second failure occurs after completion of recovery of first failure: t 2 > t 1 + t recovery (p-cycles: t recovery ~ 50 ms)