Extending the p -Cycle Concept to Path-Segment Protection

1. Extending the p-Cycle Concept to Path-Segment Protection Gangxiang Shen, Wayne D. Grover {gshen,grover@trlabs.ca} URL: http://hey.to/gxshen

2. Outline • Background and Motivation • Concept of Flow p-Cycles • Flow p-Cycle Design Model • Test Methods and Results • Operational Aspects and Potential Applications • Conclusions

3. Mesh • Span • Path • SBPP • Ring • 1+1 • UPSR • BLSR Speed Efficiency • p-Cycle • Span p-cycles (since 1998) • Flow p-cycles (our topic) Basic Approaches to Transport Network Survivability

4. On-cycle span 10 10 9 9 6 5 6 5 8 7 8 7 3 3 2 0 4 2 0 4 1 Straddling span 1 Background: Span-Protecting p-Cycles • Characteristic: Ring-like switching speed and mesh-like capacity efficiency

5. Comparison between Ring and p-Cycle Protection Ring network: p-Cycle: Spare Capacity Protection Coverage Able to restore 9 spans Able to restore 19 spans

6. p -cycles: BLSR speedmesh efficiency The Unique Position Span p-Cycles Occupy Path rest, SBPP Speed Span (link)rest. 200 ms BLSR “50 ms” 50 % 100 % 200 % Redundancy

7. Motivation • All the studies so far on p-cycles consider “span-protecting” p-cycles, so it is natural to ask: Q. is there is “a path protection equivalent to p-cycles?” -- A. Yes the answer is “Flow p-Cycles” !

8. On-cycle span 10 10 9 9 6 5 ? 6 5 8 7 8 7 ? 3 3 2 2 0 4 0 4 Straddling span 1 1 Straddling flow Concept of Flow p-Cycles • Characteristic: • Protect spans that span p-cycles can protect as well as spans that span p-cycles cannot protect (example: span 6-7 below) • Intermediate node failure restoration (example: node 7) • Path restoration –like spare capacity efficiency, 1:1 path protection –like switching speed

9. Flow p-cycles The Position Flow p-Cycles Occupy Path rest, SBPP p -cycles: BLSR speedmesh efficiency Speed Span (link)rest. 200 ms BLSR “50 ms” 50 % 100 % 200 % Redundancy

10. Various Flow-to-Cycle Relationships • Related basic concepts • Intersecting and non-intersecting • Intersection nodes • Intersection flow segment • Straddling and on-cycle flow relationship

11. 10 9 6 5 8 7 3 2 0 4 1 Straddling flow Mutual Capacity Consideration • Single span-failure causes multiple flow-failures simultaneously • Flow-based restoration is required

12. Flow p-Cycle Design Model for 100% Span Failure Restoration • Objective: minimize total spare capacity • Constraints: • Affected flows upon a span failure must be fully restored • Number of cycle copies to build is set by the largest span failure-specific simultaneous use for unit copies of cycle • The spare capacity on a span must be enough to support the number of copies of each p-cycle that overlies the span

13. Test Networks

14. Result: Performance Comparison between Various Protection Schemes

15. Operational Aspects and Protocol

16. Applications of the General Concept

17. Conclusions • Flow p-cycle concept was proposed and evaluated • Flow p-cycle method achieves path restoration –like spare capacity efficiency and 1:1 path protection –like restoration speed

18. Future Work • Identify the impacts from the network details and demand patterns • Further consider operational aspects and develop control protocol • Implement some applications of the general concept • Consider an evolutional scheme, pre-configured segments: p-segments • Compare to “ordinary” node-encircling p-cycles for node protection.