1 / 28

Adaptive Wavelength Routing in All-Optical Networks

Adaptive Wavelength Routing in All-Optical Networks. A. Mokhtar and H.S. Azizglu, IEEE/ACM Transactions on Networking, April, 1998. I. Introduction. All-Optical Network signals remain in the optical domain from the source to the destination, thereby, eliminating the electrooptic bottleneck.

gayle
Télécharger la présentation

Adaptive Wavelength Routing in All-Optical Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Adaptive Wavelength Routing in All-Optical Networks A. Mokhtar and H.S. Azizglu,IEEE/ACM Transactions on Networking,April, 1998.

  2. 2 I. Introduction • All-Optical Network • signals remain in the optical domain from the source to the destination, thereby, eliminating the electrooptic bottleneck. • Two architectures: • Broadcast-and-Select • for LAN: N x N passive broadcast star, simple. • Wavelength Routing (Fig. 1) • for WAN: optical switch, w|wo wavelength conversion, wavelength reuse.

  3. 3

  4. 4 • Routing Classification - when: • Static: does not vary with time • Adaptive: vary with time, use of network state information • Routing Classification - path assignment: • Fixed: a single path / s-d pair • Alternative: a set of paths / s-d pair • Routing Classification - path selection from: • Constrained: a subset of all possible paths • Unconstrained: all possible paths

  5. 5 • Wavelength-Routing Components (Phases): • Path Selection: to determine a path; • Wavelength Assignment: to assign a wavelength to the selected path. • without wavelength conversion • with wavelength conversion • Wavelength Assignment: • Fixed-order search • Adaptive-order search • In this paper: • Fixed/AdaptiveUnconstrained Routing (AUR)

  6. 6 • Previous works: • Chlamtac et al: • fixed routing + fixed-order wavelength search • Birman and Kershenbaum: • fixed and alternate routing + wavelength reservation with threshold protection • Birman: • Calculates approximate blocking probabilities for fixed routing with random wavelength allocation • Harai et al: • alternate routing with random wavelength allocation • Bala et al: • adaptive ordering according to the utilization • Lee and Li: • unconstrained routing with an exhaustive search

  7. 7 II. Routing and Wavelength Assignment Algorithms • For K links and W wavelengths, the state of link i, 0  i  K-1 at time t: • a column vectort(i) = (t(i)(0), t(i)(1),…, t(i)(W-1))T,wheret(i)(j)= 1 if wavelength is utilized by some connection at time t, 0 otherwise. • The state of the network at time t: • a matrixt = (t(0), t(1),…, t(k-1))

  8. 8 • The Routing and Wavelength Algorithm (RWA) searches for a path P=(i1,i2,…,il)from the source to the destination such thatt(ik)(j)=0 for all k=1,2,…,l and some j. • The optimal RWAminimizes thecall-blocking probability among all assignments. • Fixed routing:Adaptive routing: with different sorting mechanisms • PACK: most utilized wavelength first • SPREAD: least utilized wavelength first • RANDOM: in random order • EXHAUSTIVE:all paths • FIXED: in fixed order

  9. 9 III. Analysis of Fixed and Alternate Routing • Fixed and Alternate routing + Fixed-Order Search of wavelength set • A. Single-Fiber Networksnodes are interconnected by single-fiber linksB. Multiple-Fiber Networksnodes are interconnected by multiple-fiber links

  10. 10 A. Single-Fiber Networks • (Fig. 2)

  11. 11 B. Multiple-Fiber Networks • (Fig. 3) • An attractive alternative to a networkwith wavelength conversion (Fig. 4)

  12. 12 IV. Numerical Results • ARPA-2 Network (Fig. 5)Randomly Generated Topology (Fig. 6) • (Fig. 7) Blocking Prob. For ARPA-2 with 4 Wavelengths(Fig. 8) Blocking Prob. For ARPA-2 with 8 Wavelengths(Fig. 9) Blocking Prob. For Random with 4 Wavelengths(Fig. 10)Blocking Prob. For Random with 8 Wavelengths • 1. AUR/Exhaustive (higher complexity)2. AUR/Pack3. AUR/Random4. AUR/Spread5. Fixed Routing

  13. 13

  14. 14

  15. 15 • (Fig. 11)Blocking Prob. For ARPA-2 with 4/8 Wavelengths(Fig. 12)Blocking Prob. For Random with 4/8 Wavelengths • 1. AUR/Pack2. AUR/FixedBut, AUR/Fixed is closed to AUR/Pack and has lower complexity than AUR/Pack.Hence, AUR/Fixed is a good compromise between good blocking performance and moderate complexity

  16. 16

  17. 17 • (Fig. 13)Analysis vs Simulation for ARPA-2 with 4/8 W.L. (Fig. 14)Analysis vs Simulation for Random with 4/8 W.L • W=4 is more accurate than that W=8Random Network is more accurate than ARPA-2 (Note: accurate means analysis is closer to simulation)

  18. 18

  19. 19 • (Fig. 15)Blocking Prob. For Random with 4 Wavelengths(Fig. 16)Blocking Prob. For Random with 8 Wavelengths • 1. AUR/Exhaustive2. AUR/Pack3. Alternate Routing (AR)4. Fixed Routing (FR)But, When W=8 and Pb=10-3, throughput gap between FR and AR is 70% and throughput gap between AR and AUR/Pack is 50%.Hence, Alternate Routing is a practical tradeoff between Fixed Routing and AUR

  20. 20

  21. 21 • (Fig. 17)Blocking Prob. For Random with Multiple Fibers • 1. Alternate Routing with M=22. Fixed Routing with M=23. Alternate Routing with M=14. Fixed Routing with M=1 • Blocking performance improves with two fiberswith throughput increased by an factor of 4 • Throughput gain of Alternate Routing becomes more significant with two fibers.

  22. 22

  23. 23 • (Fig. 18)Blocking Prob. Vs Load per Fiber For Random with Fixed Routing • 1. M=22. M=1 • M=2 can handle double the load of M=1 • Similar for Alternate Routing • (Fig. 19)Blocking Prob. For Random with Partial Wavelength Conversion • 1. M=1, W=8 (slightly better)2. M=2, W=4 • Partial Wavelength Conversion:doubling the number of fibers per link = doubling the number of wavelengths per links

  24. 24

  25. 25 V. Complexity Analysis • (Table I and II)Average number of wavelength searchesnormalized by the number of wavelengths • 1. Spread2. Random3. Fixed (closed to Pack)4. Pack5. Exhaustive (=1)

  26. 26

  27. 27 VI. Conclusions • All-paths selection affects the blocking performance considerably, especially with light load and relatively large number of wavelengths. • Unconstrained routing improves in the call-blocking performance over constrained routing. • AUR outperforms fixed routing. • AUR also outperforms alternate routing;however, as the number of alternate routes increases, the performance approaches that of AUR.

  28. 28 • The performance gains with Adaptive Routing are more pronounced in denser network topologies as AUR takes advantage of higher network connectivity. • Incorporating network state information about wavelength utilization into the wavelength selection process is of second importance as it results in marginal improvement in the call-blocking probability. • Alternate routing is a good tradeoff between fixed routing and AUR. • Multiple-fibers networks are an attractive alternative for networks with wavelength conversion.

More Related