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The Research of Applying Random Early Blocking strategy to Dynamic Lightpath Routing

The Research of Applying Random Early Blocking strategy to Dynamic Lightpath Routing. National Yunlin University of Science & Technology. Outline. Background Related works SCP, WSCP, EWSCP Layered-Graph model Simulation of routing strategies Random Early Blocking (REB) Simulation results

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The Research of Applying Random Early Blocking strategy to Dynamic Lightpath Routing

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  1. The Research of Applying Random Early Blocking strategy to Dynamic Lightpath Routing National Yunlin University of Science & Technology

  2. Outline • Background • Related works • SCP, WSCP, EWSCP • Layered-Graph model • Simulation of routing strategies • Random Early Blocking (REB) • Simulation results • Conclusion

  3. Background • Communication service • More bandwidth is needed by customs • The poplar services • Internet, cell-phone……

  4. Background • WDM (Wavelength Division Multiplex) • Wavelengths are carried on a fiber • Bandwidth grows much

  5. Background • WDM network routing strategies • Fixed routing • Alternative routing • Adaptive routing • Routing & Wavelength Assignment (RWA) • Wavelength continuous constrain • Wavelength conversion • Converter placement

  6. The adaptive routing strategies • To search lightpath as calls coming in • Routing information • Distance vector (RIP) • Link state (OSPF)

  7. Adaptive routing – Related works • Shortest Cost Path (SCP) • The path cost function • Equal-weighted link cost • Disadvantage • Some links may be heavy traffic load • Higher blocking probability

  8. Adaptive routing – Related works • Weighted Shortest Cost Path (WSCP) • Distributing traffic load • Better network utilization • Lower blocking probability • The path cost function • Liner link cost function assignment

  9. Adaptive routing – Related works • Exponential Weighted Shortest Cost Path (EWSCP) • Light load shortest path • Medium load load balance • Heavy load avoid exhaust all wavelength on a link • Link cost function

  10. Layered-graph model • Physical network topology • N(R,L,W) • R is the set of routing nodes • L is the set of links • W is the set of wavelengths per link

  11. Layered-graph model – logical network

  12. Layered-graph model – logical network • N’(V,E,X) • V is the set of routing nodes • E is the set of links • X is the set of wavelengths per link • R’ is the set of routing nodes with conversion • Number of V is : • Number of E

  13. Simulation parameters • W=32 per network link • Full converter, sparse converter, non-converter • Different network topologies • Network traffic : • Link congestion index :

  14. Network topology 14-nodes NSFNET 8-nodes Ring

  15. Network topology 14-nodes Random Net

  16. Ring Sparse converter Full converter

  17. NSFNET full-converter

  18. NSFNET Sparse converter Non-converter

  19. Random Full converter Full converter

  20. EWSCP results • Reducing blocking probability • Load balance • Better performance than WSCP and SCP Rand Sparse converter

  21. Random Early Blocking (REB) • Early (set active threshold) • Before resource assign out • Resource conservation as heavy load • Random Blocking • Block long-lightpath randomly • Random function • Result • Reduce blocking probability much as heavy load

  22. NSFNET Left-top: Non-converter Left-bottom: Sparse converter Right: Full-converter

  23. NSFNET (full converter)

  24. Random Sparse converter Full converter

  25. Random (full converter)

  26. Conclusion • We proposed EWSCP algorithm to balance traffic load • EWSCP enhance performance than WSCP • Use exponential link cost function • Applied REB strategy to conserve resource • Increase probability of success for shorter lightpath • As heavy load, algorithm with REB has excellent performance

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