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Next-Generation ROADMs October 1, 2012 Sheldon Walklin CTO, Optelian.

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Presentation on theme: "Next-Generation ROADMs October 1, 2012 Sheldon Walklin CTO, Optelian."— Presentation transcript:

1 Next-Generation ROADMs October 1, 2012 Sheldon Walklin CTO, Optelian

2 © 2011 Optelian. All rights reserved. 2 Contents Introduction Wavelength Selective Switch Colorless, Directionless and Contentionless Flexible Bandwidth ROADMs and Transmission Beyond 100 Gb/s ROADM Control, OpenFlow and SDN Conclusion

3 © 2011 Optelian. All rights reserved. 3 Wavelength Selective Switch Functionality Nx1 WSS... SW 1 VOA 1 VOA M Common Port 1... Port N SW M

4 © 2011 Optelian. All rights reserved. Colorless, Directionless and Contentionless (CDC) 4 Colorless Any wavelength can be dynamically added/dropped without having to re-fiber a transceiver. Directionless A wavelength can be dynamically added/dropped from any direction without having to re-fiber a transceiver. Contentionless A wavelength can be re-used on all directions without any restrictions.

5 © 2011 Optelian. All rights reserved. 5 4-Degree ROADM (Colored) In general, can build an N-degree ROADM using Nx1 WSSs and 1xN splitters. The color and direction are fixed by fiber connections.

6 © 2011 Optelian. All rights reserved. 6 4-Degree ROADM (Colorless) Any transceiver wavelength (color) can be remotely configured The direction is fixed by fiber connections. Reduced number of access ports compared to colored.

7 © 2011 Optelian. All rights reserved. 7 Colorless and Directionless Wavelength Contention Structure for cross connecting between degrees remains the same as shown for the 4-degree ROADM on earlier slide.

8 © 2011 Optelian. All rights reserved. 8 Colorless, Directionless and Contentionless (using NxM WSSs)

9 © 2011 Optelian. All rights reserved. 9 Colorless, Directionless and Contentionless (using Broadcast-and-Select with Tunable Filters) 4x1 SW A Drop directions BCD 4x1 SW 4x1 SW TF 4x1 SW 4x1 SW 4x1 SW A Add directions BCD CDC add ports CDC drop ports

10 © 2011 Optelian. All rights reserved. 10 Colorless, Directionless and Contentionless (using Adjunct NxM Photonic Switches) Use NxM photonic switches to upgrade existing colored ROADMs to full CDC functionality

11 © 2011 Optelian. All rights reserved. 11 Ideal CDC WSS Concept module Non-blocking wavelength switching between any set of ports. Per wavelength attenuation control at line egress ports. Low insertion loss (up to a few dB) Very high reliability.

12 © 2011 Optelian. All rights reserved. 12 The Benefit of CDC Functionality Without CDC, cannot automatically restore optical circuit for failure on Span S1 or S6, or power failure at Node R2 or R4. CDC allows more flexibility to remotely reroute optical circuit when optimizing network utilization. Consideration: OTN and/or Layer 2+ protection and switching capabilities may reduce need for optical circuit dynamic routing.

13 © 2011 Optelian. All rights reserved. 13 Flexible Bandwidth ROADMs Flexible bandwidth (FB) ROADMs (aka gridless ROADMs) allow the passband center and/or width to be dynamically adjusted. Many people advocate that FB ROADMs will be required to support bit rates beyond 100G.

14 © 2011 Optelian. All rights reserved. 14 Considerations for Transmission Beyond 100 Gb/s For 40G and 100G transmission, the client interface has transitioned to parallel optics, while the line interface has retained single-carrier optics for improved transmission capacity. Parallel optics will likely be required on the line interface for bit rates approaching 1 Tb/s and beyond. Multi-carrier channels or superchannels are likely to be used for long- haul transmission beyond 100 Gb/s, with PDM-QPSK used for each constituent carrier. PDM-xQAM may be used in Metro (shorter distance) applications. Although FB ROADMs may provide improved spectral efficiency, they are not required for transmission beyond 100 Gb/s.

15 © 2011 Optelian. All rights reserved. ROADM Control 15 Automated Optical Layer Controls the power level of each wavelength at ROADM ports to a set target (Automatic Power Balancing) Span or link gain control Automated Wavelength Circuit Provisioning Impairment-aware path computation (wavelength routing) ROADM switch configuration

16 © 2011 Optelian. All rights reserved. Automated Wavelength Circuit Provisioning 16 Connection Controller Path Computation Element A-to-Z circuit request with routing constraints viable route(s) and required regen location(s) impairment-aware Optical Network Optical Network wavelength circuit request signaling done 5

17 © 2011 Optelian. All rights reserved. OpenFlow and SDN 17 R2 R3 R7 R4 R1 R8 R5 R6 s1 s3 s2 s10 s5 s4 s7 s11 s12 s6 s8 s9 OpenFlow Controller App Centralized dynamic control Simple flow table entry at each ROADM for wavelength connection Smart Apps – must be aware of topology, resource availability and state, fiber properties, impairment modeling, etc. Opportunity for OpenFlow applications to have multi- layer control and visibility Apps can evolve independently of physical network

18 © 2011 Optelian. All rights reserved. 18 Conclusion Current generation ROADMs use WSS modules and have colored or colorless access ports. CDC functionality generally has a higher capital cost and lower access port density, but may provide lower operational costs. FB ROADMs may provide improved spectral efficiency, but are not required to achieve transmission beyond 100 Gb/s Multi-carrier channels or superchannels will likely be used for long-haul transmission beyond 100 Gb/s, with PDM-QPSK used for each constituent carrier. PDM-xQAM may see application in the Metro Automated ROADM networks are well-suited to centralized control, making OpenFlow a good match. This could also facilitate multi-layer control.

19 Thank You


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