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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 1 — Jan. 14, 2013
  • pp: 469–477
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A novel large-scale OXC architecture and an experimental system that utilizes wavelength path switching and fiber selection

Toshinori Ban, Hiroshi Hasegawa, Ken-ichi Sato, Toshio Watanabe, and Hiroshi Takahashi  »View Author Affiliations


Optics Express, Vol. 21, Issue 1, pp. 469-477 (2013)
http://dx.doi.org/10.1364/OE.21.000469


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Abstract

We propose a novel large-scale OXC architecture that utilizes WSSs for dynamic wavelength grouping and 1xn switches for fiber selection. We also develop a network design algorithm that can make the best use of the routing capability of the proposed nodes. Numerical experiments on several topologies show that the architecture attains substantial hardware scale reduction. A prototype demonstrates good transmission performance and confirms the technical feasibility of the proposed OXC architecture.

© 2013 OSA

1. Introduction

The rapid growth of Internet traffic spurred by the penetration of broadband access is driving the introduction of photonic networks. To cope with the future expected traffic increase, driven by the advancement of video technologies including high-definition and ultra-high-definition TV (72 Gbps, uncompressed) [1

1. K. Sato and H. Hasegawa, “Optical networking technologies that will create future bandwidth-abundant networks,” J. Opt. Commun. Netw. 1(2), A81–A93 (2009). [CrossRef]

] and future advanced services [2

2. A. L. Chiu, G. Choudhury, G. Clapp, R. Doverspike, M. Feuer, J. W. Gannett, J. Jackel, G. Kim, J. Klincewicz, T. Kwon, G. Li, P. Magill, J. M. Simmons, R. A. Skoog, J. Strand, A. Lehmen, B. J. Wilson, S. Woodward, and D. Xu, “Architectures and Protocols for Capacity Efficient, Highly Dynamic and Highly Resilient Core Networks [Invited],” J. Opt. Commun. Netw. 4(1), 1–14 (2012). [CrossRef]

], the number of fibers connecting pairs of adjacent nodes need to be substantially increased. When we consider space switches, a 3-D micro-electro mechanical systems (MEMS) switch up to ~320x320 appears commercially feasible and a 512x512-port switch has been tested [3

3. Y. Kawajiri, “512x512-port 3D-MEMS optical switch modules with a concave mirror,” IEICE Tech. Rep. 108, 17–20 (2009).

]. However, if we want to create, for example, a 48 fiber x 48 fiber wavelength cross-connect, where each fiber carries 96 λs, 96 48x48 optical space switches are required, this scale is not practical. Presently, most OXCs(/ROADMs) utilize wavelength selective switches (WSSs), however, the maximum available number of output ports is limited to 20 + . To meet the future traffic demand, cost effective and scalable large-scale optical cross-connects (OXCs) are indispensable [4

4. S. Woodward, “Balancing costs & benefits in a flexible grid network?” in Optical Fiber Communication Conference (2012), workshop OSu1B.

].

2. Proposed node architecture

An equivalent architecture to Fig. 1 is shown in Fig. 2
Fig. 2 Proposed node architectures based on Delivery and Coupling switches (DCSWs). Each DCSW corresponds to the same color parts in Fig. 1.
. This architecture utilizes a Dx=1nx x nx DCSW, which integrates Dx=1nx arrayed 1xnx SWs and nx arrayed Dx=1nxx1 OCs. The number of fibers that interconnect component optical devices is reduced to D/Dx=1nx (see Fig. 1 and Fig. 2), which eases fabrication.

The number of selectable output fibers, k, can be increased. Figure 3
Fig. 3 Proposed architecture when the number of selectable parallel fibers k = 2.
shows the case for k = 2. The degree of WSSs and the number of 1xnx SWs increase with k. Increasing k enhances node routing capability, but also the hardware scale. The important task of network design is to attain the necessary node routing capability while keeping k to the minimum value possible.

3. Network design algorithm

3.1 Virtual topology construction that considers switching states

3.2 Proposed network design algorithm

The structure of the proposed algorithm is summarized as follows.

<Optical path network design algorithm considering dynamic wavelength grouping and fiber selection>

  • Step 1 Search for the demand whose shortest hop count between the source and destination node pair is the largest among the given demands. Find a pair of route and wavelength index that minimizes the fiber increment by applying Dijkstra’s algorithm on the virtual topology graphs. Update the link weight following switching states.
  • Step 2 Based on the selected node pair and its shortest route found in Step 1, create a set of demands that consist of the destination node and plural source nodes. The source nodes should satisfy; the shortest route that connects each source node of the set and the destination node contains the node that is one-hop before the destination node on the shortest route found in Step 1.
  • Step 3 Find the shortest path tree with the virtual destination node as the root of the tree by applying Dijkstra’s algorithm on the virtual topologies and assign a pair of route and index of wavelength to the demand that has the shortest weight. Remove the demand from the demand set and update the link weight.
  • Step 4 Repeat Step 3 until either the demand set is empty or the capacity of the fiber as the virtual destination node is filled.
  • Step 5 Repeat Step 1 to Step 4 until all demands are accommodated.

The one-hop demands, whose shortest hop count between the source and destination node pair is one, do not transit any nodes. Therefore, such demands are assigned after finishing Step 4. The remaining one-hop demands are assigned after all demands whose shortest hop counts are two or more than two are assigned.

4. Numerical experiments

We compared the performance of networks with proposed switch architecture to those with conventional switches composed of large-scale WSSs. We use the following parameters: a 5x5 regular mesh network, the COST266 pan-European network model [10

10. R. Inkret, A. Kuchar, and B. Mikac, “Advanced infrastructure for photonic networks – extended final report of COST action 266,” (2003). http://www.ikr.uni-stuttgart.de/Content/Publications/View/FullPage.html?36355.

] with 26 nodes and 51 links, and the Italia network model [11

11. P. Pagnan, C. Cavazzoni, and A. D’Alessandro, “ASON implementation in Telecom Italia backbone network,” in European Conference on Optical Communication (2006), Workshop 3. http://www.ist-mupbed.org/ECOC06/pdfs/ECOC06-Workshop3-TelecomItalia.pdf/.

] with 31 nodes and 49 links, see Fig. 5
Fig. 5 Experimental network topologies.
. Wavelength conversion was not considered, fiber capacity is 80 wavelengths, and randomly distributed traffic demands, represented as the average number of wavelength paths between each node pair. The necessary number of fibers was the average of 10 trials with different traffic distributions, and was normalized against that of the conventional networks. Figures 6
Fig. 6 Normalized number of fibers for 5x5 network.
, 7
Fig. 7 Normalized number of fibers for COST266 network.
and 8
Fig. 8 Normalized number of fibers for Italia network.
show normalized number of fibers for each network topology tested for different values of k. These figures show that the proposed networks need more fibers in the small traffic demand area, however, the fiber increment rapidly decreases as the demand becomes large. For a 5x5 regular mesh network, the increment is less than 10% when wavelength path demand is larger than 5 and k≥2. It reaches 0.4% when the demand is 28 and k≥3. For the COST266 network, it is less than 10% when the demand is larger than 10 and k≥2. It reaches 2.9% when the demand is 32 and k≥3. For the Italia network, it is less than 10% when the demand is larger than 7 and k≥2. It reaches 1.1% when the demand is 32 and k = 4. Please note that this node architecture targets networks with large traffic demands.

Regarding hardware scale, the average input/output fiber count of the largest node in COST266 is, at average traffic volume of 20, 50/50, which means that 50 1x50 WSSs or 150 1x20 WSSs are required for the conventional node. While with our architecture (at k = 2) the average input/output fiber count is 55/52, and hence 55 1x20 WSSs and 52 1xn (n≤11) SWs are required. In the Italia network, the average input/output fiber count of the largest node is, at the average traffic volume of 20, 77/77, which means that 77 1x77 WSSs or 324 1x20 WSSs are required for the conventional node. While with our architecture (at k = 2) the average input/output fiber count is 80/75, and hence 80 1x20 WSSs and 75 1xn (n≤28) SWs are required. The hardware requirement is thus significantly reduced.

5. Transmission experiments

6. Conclusions

We proposed a novel large-scale OXC node architecture that consists of small-degree WSSs and 1xn SWs. We also proposed an optical path network design algorithm that can make the best use of the proposed architecture. Numerical experiments verified that it offers significant hardware scale reduction at the cost of a few additional fibers. We developed a prototype system and verified its technical feasibility through transmission experiments.

Acknowledgment

The authors would like to thank researchers of NEL for their valuable discussions. This work was partly supported by NICT λ-reach project and KAKENHI (23246072).

References and links

1.

K. Sato and H. Hasegawa, “Optical networking technologies that will create future bandwidth-abundant networks,” J. Opt. Commun. Netw. 1(2), A81–A93 (2009). [CrossRef]

2.

A. L. Chiu, G. Choudhury, G. Clapp, R. Doverspike, M. Feuer, J. W. Gannett, J. Jackel, G. Kim, J. Klincewicz, T. Kwon, G. Li, P. Magill, J. M. Simmons, R. A. Skoog, J. Strand, A. Lehmen, B. J. Wilson, S. Woodward, and D. Xu, “Architectures and Protocols for Capacity Efficient, Highly Dynamic and Highly Resilient Core Networks [Invited],” J. Opt. Commun. Netw. 4(1), 1–14 (2012). [CrossRef]

3.

Y. Kawajiri, “512x512-port 3D-MEMS optical switch modules with a concave mirror,” IEICE Tech. Rep. 108, 17–20 (2009).

4.

S. Woodward, “Balancing costs & benefits in a flexible grid network?” in Optical Fiber Communication Conference (2012), workshop OSu1B.

5.

P. Pagnan and M. Schiano, “A λ switched photonic network for the new transport backbone of Telecom Italia,” in Proceedings of Conference on Photonics in Switching (2009), paper ThII2–1.

6.

T. Watanabe, T. Goh, M. Okuno, S. Sohma, T. Shibata, M. Itoh, M. Kobayashi, M. Ishii, A. Sugita, and Y. Hibino, “Silica-based PLC 1x128 thermo-optic switch,” in Proceedings of Conference on European Conference on Optical Communication (2001), paper Tu.L.1.2.

7.

T. Watanabe, Y. Hashizume, and H. Takahashi, “Double-branched 1x29 silica-based PLC switch with low loss and low power consumption,” in Proceedings of Conference on Microoptics Conference (2011), paper J-2.

8.

K. Sato, Advances in transport network technologies -Photonic networks, ATM and SDH- (Artech House, 1996).

9.

T. Ban, H. Hasegawa, K. Sato, T. Watanabe, and H. Takahashi, “A novel large-scale OXC architecture that employs wavelength path switching and fiber selection,” in Proceedings of Conference on European Conference on Optical Communication (2012), paper We.3.D.1.

10.

R. Inkret, A. Kuchar, and B. Mikac, “Advanced infrastructure for photonic networks – extended final report of COST action 266,” (2003). http://www.ikr.uni-stuttgart.de/Content/Publications/View/FullPage.html?36355.

11.

P. Pagnan, C. Cavazzoni, and A. D’Alessandro, “ASON implementation in Telecom Italia backbone network,” in European Conference on Optical Communication (2006), Workshop 3. http://www.ist-mupbed.org/ECOC06/pdfs/ECOC06-Workshop3-TelecomItalia.pdf/.

12.

T. Watanabe, K. Suzuki, and T. Takahashi, “Silica-based PLC transponder aggregators for colorless, directionless, and contentionless ROADM,” in Optical Fiber Communication Conference, OSA Technical Digest (CD) (Optical Society of America, 2012), paper OTh3D.1.

OCIS Codes
(060.4251) Fiber optics and optical communications : Networks, assignment and routing algorithms
(060.4265) Fiber optics and optical communications : Networks, wavelength routing

ToC Category:
Backbone and Core Networks

History
Original Manuscript: October 1, 2012
Manuscript Accepted: November 16, 2012
Published: January 7, 2013

Virtual Issues
European Conference on Optical Communication 2012 (2012) Optics Express

Citation
Toshinori Ban, Hiroshi Hasegawa, Ken-ichi Sato, Toshio Watanabe, and Hiroshi Takahashi, "A novel large-scale OXC architecture and an experimental system that utilizes wavelength path switching and fiber selection," Opt. Express 21, 469-477 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-1-469


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References

  1. K. Sato and H. Hasegawa, “Optical networking technologies that will create future bandwidth-abundant networks,” J. Opt. Commun. Netw.1(2), A81–A93 (2009). [CrossRef]
  2. A. L. Chiu, G. Choudhury, G. Clapp, R. Doverspike, M. Feuer, J. W. Gannett, J. Jackel, G. Kim, J. Klincewicz, T. Kwon, G. Li, P. Magill, J. M. Simmons, R. A. Skoog, J. Strand, A. Lehmen, B. J. Wilson, S. Woodward, and D. Xu, “Architectures and Protocols for Capacity Efficient, Highly Dynamic and Highly Resilient Core Networks [Invited],” J. Opt. Commun. Netw.4(1), 1–14 (2012). [CrossRef]
  3. Y. Kawajiri, “512x512-port 3D-MEMS optical switch modules with a concave mirror,” IEICE Tech. Rep.108, 17–20 (2009).
  4. S. Woodward, “Balancing costs & benefits in a flexible grid network?” in Optical Fiber Communication Conference (2012), workshop OSu1B.
  5. P. Pagnan and M. Schiano, “A λ switched photonic network for the new transport backbone of Telecom Italia,” in Proceedings of Conference on Photonics in Switching (2009), paper ThII2–1.
  6. T. Watanabe, T. Goh, M. Okuno, S. Sohma, T. Shibata, M. Itoh, M. Kobayashi, M. Ishii, A. Sugita, and Y. Hibino, “Silica-based PLC 1x128 thermo-optic switch,” in Proceedings of Conference on European Conference on Optical Communication (2001), paper Tu.L.1.2.
  7. T. Watanabe, Y. Hashizume, and H. Takahashi, “Double-branched 1x29 silica-based PLC switch with low loss and low power consumption,” in Proceedings of Conference on Microoptics Conference (2011), paper J-2.
  8. K. Sato, Advances in transport network technologies -Photonic networks, ATM and SDH- (Artech House, 1996).
  9. T. Ban, H. Hasegawa, K. Sato, T. Watanabe, and H. Takahashi, “A novel large-scale OXC architecture that employs wavelength path switching and fiber selection,” in Proceedings of Conference on European Conference on Optical Communication (2012), paper We.3.D.1.
  10. R. Inkret, A. Kuchar, and B. Mikac, “Advanced infrastructure for photonic networks – extended final report of COST action 266,” (2003). http://www.ikr.uni-stuttgart.de/Content/Publications/View/FullPage.html?36355 .
  11. P. Pagnan, C. Cavazzoni, and A. D’Alessandro, “ASON implementation in Telecom Italia backbone network,” in European Conference on Optical Communication (2006), Workshop 3. http://www.ist-mupbed.org/ECOC06/pdfs/ECOC06-Workshop3-TelecomItalia.pdf/ .
  12. T. Watanabe, K. Suzuki, and T. Takahashi, “Silica-based PLC transponder aggregators for colorless, directionless, and contentionless ROADM,” in Optical Fiber Communication Conference, OSA Technical Digest (CD) (Optical Society of America, 2012), paper OTh3D.1.

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