An OMNeT++ Model for the Evaluation of OBS Routing Strategies

Transcription

1 An OMNeT++ Model for the Evaluation of OBS Routing Strategies A.L. Barradas, M.C.R. Medeiros Center for Electronic, Optoelectronic and Telecommunications (CEOT) Faculty of Science and Technology, University of Algarve, Portugal s: {abarra, Presentation for OMNeT SIMUTOOLS 2008 March 7, 2008, Marseille, France

2 Outline Introduction Proposed Routing Strategies Network Simulation Model Performance Results Conclusion Alvaro Barradas for OMNeT , March, 7, Marseille, France 2 / 24

3 Introduction Optical Switching Paradigms Optical Circuit Switching (OCS) Optical Packet Switching (OPS) Optical Burst Switching (OBS) Alvaro Barradas for OMNeT , March, 7, Marseille, France 3 / 24

4 Introduction Optical Switching Paradigms OCS Establishes an end-to-end pipe (wavelength/lightpath) Mature technology Good QoS for admitted traffic Large wavelength granularity Long reconfiguration delay Not suitable for bursts or short-lived sessions Alvaro Barradas for OMNeT , March, 7, Marseille, France 4 / 24

5 Introduction Optical Switching Paradigms OPS Similar to e-packet switching Familiar architecture Great flexibility and statistical multiplexing Per packet processing overhead Stringent synch & switching requirements Technological limitation (... no optical RAM!) Alvaro Barradas for OMNeT , March, 7, Marseille, France 5 / 24

6 Introduction Optical Switching Paradigms OBS Leverages the best of electronics and optics * Moderate processing overhead Asynchronous switching Low signaling delay and high statistical multiplexing Lack of optical RAM causes burst dropping Moderate/Fast switching also needed Relatively new, unfamiliar technology * Chunming Qiao Int l Workshop on Future Optical Networks, March 5, 2006, Anaheim, CA, USA. Alvaro Barradas for OMNeT , March, 7, Marseille, France 6 / 24

7 Introduction Optical Switching Paradigms A comparison table by: K.C. Chua, M. Gurusamy, Y. Liu and M.H. Phung Quality of Service in Optical Burst Switched Networks Springer, 2007 Alvaro Barradas for OMNeT , March, 7, Marseille, France 7 / 24

8 Introduction OBS reliability issues Leverages the best of electronics and optics, but... Burst loss: One way reservation Burst transmission without waiting for permission demands > resources ( Collisions ) Contention resolution scheme Space Time Wavelength Burst drop Alvaro Barradas for OMNeT , March, 7, Marseille, France 8 / 24

9 Proposed Routing Strategies Minimize Maximum Congested Link (MCL) Subject to Minimize ³ MAX (1) X X s;d X ¾ v = 1; 8s; d 2 N (2) v2v s;d v2v s;d ¾ v p v l t s;d ³ MAX ; 8l 2 L (3) ¾ v 2 f0; 1g; non-negative integer: ³ MAX (4) Alvaro Barradas for OMNeT , March, 7, Marseille, France 9 / 24

10 Proposed Routing Strategies Minimize Maximum End-to-end Congestion (MEC) Subject to Minimize ' MAX (5) X ¾ v = 1; 8s; d 2 N (6) v2v s;d v;v0 (¾ v + ¾ v0 1) q v;v0 ; 8v 2 V; 8v 0 2 V n V s(v);d(v) (7) t s;d + X X 0 t s(v0 );d(v 0 ) ' MAX ; 8s; d 2 N (8) v2v s;d v 0 2VnV s;d v;v ¾ v ; v;v0 2 f0; 1g; non-negative integer: ' MAX (9) Alvaro Barradas for OMNeT , March, 7, Marseille, France 10 / 24

11 Simulation Model A conceptual view 1 st. stage network specifications ILP formalization optimizer K input paths A set of K input paths for each pair of nodes in this study K shortest paths with less links in common routing tables protocol behavior K {2, 3, 4} 2 nd. stage simulator simulation results Alvaro Barradas for OMNeT , March, 7, Marseille, France 11 / 24

12 Simulation Model The OBS network global characteristics The COST 239 topology Copenhagen W=16 λs / link 10 Gbit / channel Poisson pattern traffic London Amsterdam Berlin Luxemburg Brussels Prague Threshold-based bursts (100 KB) Symmetric traffic matrix JET signaling scheme Paris Zurich Vienna Source routing decision (MCL / MEC) Milano Full wavelength conversion Alvaro Barradas for OMNeT , March, 7, Marseille, France 12 / 24

13 Simulation Model The adopted OBS architecture WDM Link CPH Burst offset Access Layer Optical Backbone Edge Router Core Router Alvaro Barradas for OMNeT , March, 7, Marseille, France 13 / 24

14 Simulation Model Network topologies under study ARPANET random12 NSFnet COST239 Alvaro Barradas for OMNeT , March, 7, Marseille, France 14 / 24

15 Simulation Model Snapshot of COST239 * * in OMNeT++ Alvaro Barradas for OMNeT , March, 7, Marseille, France 15 / 24

16 Simulation Model Snapshot of ARPANET * * in OMNeT++ Alvaro Barradas for OMNeT , March, 7, Marseille, France 16 / 24

17 Simulation Model Snapshot of NSFnet * * in OMNeT++ Alvaro Barradas for OMNeT , March, 7, Marseille, France 17 / 24

18 Simulation Model Snapshots of submodules * corenode edgenode actions in space dimension * in OMNeT++ actions in wavelength dimension Alvaro Barradas for OMNeT , March, 7, Marseille, France 18 / 24

19 Simulation Model Structure of the edgenode abarra@ceotserver:~/cost239$ cat cost239_sp_s9.rte abarra@ceotserver:~/cost239$ routingtable.h class RoutingTable : public csimplemodule { private: struct RouteEntry { std::vector<int> route; int numofhops; bool accessed; }; // container for Routing Table std::vector<routeentry> routingtable; public: //... source routing is used } protected: //... Alvaro Barradas for OMNeT , March, 7, Marseille, France 19 / 24

20 Simulation Model Behavior of the corenode handlemessage // Function called for each event if msg is a Control Packet Header processcph else if msg is an Optical Burst processburst else, it is a selfmessage processholdingtimer Alvaro Barradas for OMNeT , March, 7, Marseille, France 20 / 24

21 Performance Evaluation Simulation model 11 nodes 26 b-links 4.73 av-degree W=16 10Gbps/w 11E+06 bursts L=100KB Poisson TP Symmetric TM Full Wconv Alvaro Barradas for OMNeT , March, 7, Marseille, France 21 / 24

22 Performance Evaluation Simulation model 11 nodes 26 b-links 4.73 av-degree W=16 10Gbps/w 11E+06 bursts L=100KB Poisson TP Symmetric TM Full Wconv Alvaro Barradas for OMNeT , March, 7, Marseille, France 22 / 24

23 Performance Evaluation Alvaro Barradas for OMNeT , March, 7, Marseille, France 23 / 24

24 Conclusion Both routing strategies (MCL and MEC) behave better than the shortest path approach. Acknowledgments: Ending An OMNeT++ simulation model was created for routing path evaluation in OBS networks. Two routing strategies for OBS networks are presented and evaluated It is possible to reduce burst loss taking preventive actions on the space domain. (Performance results may also depend on the network connectivity..., further research is needed). Network simulation model is being prepared for future work. Thank you Alvaro Barradas for OMNeT , March, 7, Marseille, France 24 / 24