1. Load Balancing in Protection Switching of Optical Networks Hongkyu Jeong, Gyu-Myoung Lee Information and Communications Univ. (ICU) Student ID : 20022130, 2000520 E-mail: paul@icu.ac.kr, gmlee@icu.ac.kr

2. -2- Outline I.Introduction II.Proposed Path Selection Mechanism III.Simulation Assumptions IV.Numerical Results and Analysis V.Conclusion and Future Works VI.References

3. -3- Introduction Traffic of multimedia data has been increasing Survivability of optical network has become one of the pivotal issues In the real world, 1+1 or 1:1 protection mechanism commonly has been adopted Resource utilization of those protection schemes is at most 50% low when applied to optical networks Sharing rate of backup path is noticeably low Recently, traffic engineering concept of GMPLS is introduced Improvement on network resource utilization through load- balancing is becoming the important issue

4. -4- Introduction (cont.) Analyze four path selection models Preconfigured protection scheme Assumption Load is the call request to reserve wavelength for working path (WP) and backup path (BP) Achieve higher utilization rate of BP By introducing the concept of load-balancing where selecting policies are adopted for models Achieve 100% restoration By not selecting the BP that has the WP within the same SRLG

5. -5- Proposed Path Selection Mechanism First, find shortest path set Second, select three disjointed shortest paths in the shortest path set by each specific policy Most shortest path is used for WP If there are call requests which have same source node and destination node pair, same paths are used for reserving WP and BP Third, when a call request is arrived at a source node, the node finds a wavelength for WP Reserve or reject Fig.1 Simplified flow of proposed mechanism

6. -6- Proposed Path Selection Mechanism (cont.) Fourth, nodes preferentially finds a wavelength for BP which can be shared If there is no sharable wavelength, unused wavelength is reserved for BP If there is no unused wavelength, the call request is rejected Only when it is possible to reserve both WP and BP Call request is accepted and wavelength reserving mechanism is completed Fig.1 Simplified flow of proposed mechanism

7. -7- Simulation Assumptions Find shortest path set from a node to other node Select shortest paths for WP and BP by the policy of each model For the selected model, case 1 and case 2 are alternately selected as shown in Table 1 Case 1 Case 2 Model 1 WP: path1 No use BP: path2 Model 2 WP: path1 WP: path2 BP: path2 BP: path1 Model 3 WP: path1 BP: path2 BP: path3 Model 4 WP: path1 WP: path3 BP: path2 Table 1. path selection policies of four different models

8. -8- Simulation Assumptions (cont.) Each link capacity (W) Unlimited in the case of evaluating sharing rate 32 and 64 wavelengths are used to evaluate the call request blocking rate The number of node N is 16 Call request is 8*load (load is positive integer) Each node has no wavelength converter WP and BP are disjointed path When we look for a sharable wavelength for BP, the wavelength should not be shared by BPs that have the WP which belongs to the same SRLG

9. -9- Simulation Assumptions (cont.) Torus topology (Fig.2) It has not only many paths but also similar lengths (number of nodes to be passed) from a source to a destination Similar characteristics which topologies in the real world possess For each call requests, the WP and BP are randomly chosen from the shortest path set For each experiment we run 50 times simulation, and then take the average Fig.2 A 2-dimensioinal 4X4 Torus Toplogy

10. -10- Simulation Assumptions (cont.) Sharing rate:, where : Accepted request for reserving BP where : Accepted request for reserving BP : Wavelength used for reserving BP Blocking rate:, where : Number of call requests where : Number of call requests : Number of accepted call requests

11. -11- Numerical Results and Analysis Fig.3 Shows model 2,3, and 4 which adopt load-balancing scheme manifest higher sharing rate compared to model1 which does not adopt the load-balancing scheme Shape of graph is regular at each model Sharing rate of model 4 Improved on average 30% compared with that of model 1Improved on average 30% compared with that of model 1 Fig.3 Backup Path Sharing Rate of model 1~4

12. -12- Numerical Results and Analysis (cont.) Fig.4 (W=32) Model 2,3, and 4 have lower blocking rate than that of model 1 Model 4 has average 23% lower blocking rate Achieve higher network throughputAchieve higher network throughput Expectation: growing load balancing effect More nodes, links, and wavelengths per linkMore nodes, links, and wavelengths per link Fig.4 Call Request Blocking Rate of model 1~4

13. -13- Numerical Results and Analysis (cont.) Fig. 5 (W=64) Improved load balancing effect by doubling the number of wavelengths to 64 Model 4 shows 26% lower blocking rate on average than that of model 1 Fig.5 Call Request Blocking Rate of model 1~4

14. -14- Conclusion and Future works Introduce the concept of load balancing into protection mechanism Achieve 30% higher sharing rate and 23% (w=32), 26% (w=64) lower blocking rate compared to the commonly used 1:1 protection mechanism (model 1) Maintain 100% restoration capability Future Works Apply proposed mechanism to various mesh topologies Use the concept of threshold in order to enhance the positive effect of load balancing

15. -15- References [1] Ayan Banerjee et al. “Generalized Multiprotocol Label Switching: An Overview of Signaling Enhancements and Recovery Techniques”, IEEE Communication Magazine, July 2001 [2] Ayan Banerjee et al. “Generalized Multiprotocol Label Switching: An Overview of Routing and Management Enhancements”, IEEE Communication Magazine, Jan. 2001 [3] S. Ramamurthy and Biswanath Mukherjee, “Survivable WDM mesh networks, part Ⅰ – protection”, INFOCOM ’99, March 1999, Page(s): 744 -751 vol.2 [4], IETF draft

16. -16- Thank you ! Q & A