Benefits of p -Cycles in a Mixed Protection and Restoration Approach

1. Benefits of p-Cycles in a Mixed Protection and Restoration Approach François Blouin, Anthony Sack, Wayne D. Grover, Hadi Nasrallah October 21, 2003 Fourth International Workshop on the Design of Reliable Communication Networks (DRCN 2003)19-22 October 2003 - Banff, Alberta, Canada

2. Introduction • Multiple protection and restoration methods may co-exist in optical mesh networks • Automatic protection switching (APS), shared backup path protection (SBPP), mesh span restoration, redial, etc. • Benefits of adding p-cycles to a set of these methods? • Benefits of planning network capacity jointly for these methods? New joint planning model

3. Capacity redundancy vs. Restoration time APS 1+1 Capacity redundancy p-Cycles Mesh Span Restoration Shared Backup Path Protection True Mesh Path Restoration Restoration time

4. Applications Restoration time requirement Demand mix (example case) 15% ≤ 60 ms 30% ≤ 80 ms 55% ≤ 200 ms Service model Network services Class of Protection (CoP) Restoration time APS 1+1 60 ms p-Cycles 80 ms SBPP 200 ms Fixed CoP selection (without p-cycles) Other possible CoPs, e.g. Unprotected and Redial, not included in analysis.

5. Applications Restoration time requirement Demand mix (example case) 15% ≤ 60 ms 30% ≤ 80 ms 55% ≤ 200 ms Service model Network services Class of Protection (CoP) Restoration time APS 1+1 60 ms p-Cycles 80 ms SBPP 200 ms Fixed CoP selection (with p-cycles) Other possible CoPs, e.g. Unprotected and Redial, not included in analysis.

6. Applications Restoration time requirement Demand mix (example case) 15% ≤ 60 ms 30% ≤ 80 ms 55% ≤ 200 ms Service model Network services Class of Protection (CoP) Restoration time APS 1+1 60 ms p-Cycles 80 ms SBPP 200 ms Automatic CoP selection with upgrades Other possible CoPs, e.g. Unprotected and Redial, not included in analysis.

7. Planning models Integer Linear Programming general model (AMPL, CPLEX) • Minimal capacity•distance for full restorability under single failures • Selection of fastest CoPs Min Separate optimization (fixed CoP selection) Joint optimization (automatic CoP selection) Upgrade to faster CoP whenever economical Without p-Cycles (benchmark) With p-Cycles With p-Cycles or 3 2 1

8. Two network models Europe Average nodal degree = 4.73 U.S. Average nodal degree = 3.26

9. Results – U.S. network Benchmark -3.4% -8.7% CoP upgraded demands: 32% 1 2 3

10. Results – Europe network Benchmark -11.6% -14% CoP upgraded demands: 24% 1 2 3

11. p-cycle Class of Protection upgrade examples B C Upgrade from p-cycle to APS 1+1 A working E D Upgrade from SBPP to p-cycle

12. APS “spare” p-cycle cap = 10 B C w3 = 20 w2 = 10 A w1 cap = 10 E D Class of Protection upgrade examples B C Upgrade from p-cycle to APS 1+1 A working E D Upgrade from SBPP to p-cycle

13. Conclusions • p-Cycles could replace APS 1+1 for some traffic demands • where slight restoration time penalty is acceptable

14. Conclusions • p-Cycles could replace APS 1+1 for some traffic demands • where slight restoration time penalty is acceptable • New capacity planning model allowing automatic selection of protection & restoration method • Upgrade demand to faster CoP whenever economical

15. Conclusions • p-Cycles could replace APS 1+1 for some traffic demands • where slight restoration time penalty is acceptable • New capacity planning model allowing automatic selection of protection & restoration method • Upgrade demand to faster CoP whenever economical • Mixed protection & restoration: • Adding p-cycles: 1% - 19% capacity savings • Jointly plan all CoPs: 4% - 22% capacity savings • Upgrades to faster CoP: 0 - 45% Provide better service for some traffic without adding capacity

16. Thank you