Ciena uses software to dip into the photonic layer

Ciena has enhanced its control plane and line elements to enable software to control the optical networking layer. The additions are part of Ciena's OPn network architecture evolution to enable greater visibility and automation. "It is about putting software into a system to allow you to program the photonic line," says Michael Adams, vice president of product & technology marketing at Ciena.

"For an SDN controller to control a photonic line, we need to present it as a programmable layer. The infrastructure is now there to be programmed."

Michael Adams, Ciena

Dubbed WaveLogic Photonics, the enhancements address the optical line system, made up of Ciena's WaveLogic coherent module, amplifier and reconfigurable optical add/ drop multiplexer (ROADM) elements. Ciena's ROADM is colourless and directionless and supports flexible-grid lightpaths, while the contentionless attribute will be added in the second half of the year.     

Making the optical layer programmable is tricky. The OTN, Ethernet and IP networking layers above the line system are digital, lending themselves to software control. The optical layer, however, is not. Its performance is determined by linear and non-linear fibre transmission effects and parameters such as the optical signal-to-noise ratio.

"We believe the photonic line is equally important to be programmed, but the challenge has been that it is an analogue domain," says Adams.

To this aim, Ciena's WaveLogic Photonics introduces three changes:

• The OneConnect Intelligent Control Plane has been extended to include the photonic layer.
• Software-based line monitoring has been added to Raman to simplify amplifier deployment.
• Network analytics has been introduced to identify faults and optical signal loss.   

By extending the OneConnect Control Plane to the photonic level, service providers can offer customers more tailored service-level agreements (SLAs). Customers that want protection against double fibre cuts can add automated optical restoration. After the first cut, the 50-millisecond OTN layer restoration kicks in. If a second cut occurs, OneConnect will restore the network in tens of seconds. At present, a truck roll and manual repair is needed after the second cut and that can take hours to repair. "The combination of the two [OTN and optical restoration] gives you a much more flexible system of SLAs that can be offered," says Adams.   

The second line system enhancement, dubbed Smart Raman, adds a software-based optical time-domain reflectometer (OTDR) to Ciena's hybrid Raman/ EDFA amplifiers to simplify their deployment. The OTDR enables the amp to monitor and characterise the line.

"The Raman provides simple and controlled turn-up and will not turn on until it has checked that the surrounding fibre does not have any high losses," says Adams. Such automation replaces the careful manual configuration otherwise required when deploying high-powered Raman amps.

Ciena is also using the line data collected by the OTDR to provide network analytics. The line's condition can be plotted over time, helping identify any degradation in line elements. The analytics will also locate faults across fibre spans without requiring a truck roll. "Now from the NOC [network operations centre], that [fault] visibility is within 3m," says Adams.

Comcast has already used Smart Raman and the analytics as part of a Terabit trial conducted with Ciena. The cable operator located signal loss points on the line. "Comcast was able to recover several dBs of margin on that fibre," says Adams. "With 16-QAM used for the Terabit trial, they were able to go much farther; they achieved 1,000km even on marginal fibre." Ciena will also introduce advanced 16-QAM signaling in the second half of the year.

Ciena says WaveLogic Photonics should be viewed as enhancing the OneConnect control plane at the OTN and optical levels, while paving the way for software-defined networking (SDN) and applications-driven automation.

"For an SDN controller to control a photonic line, we need to present it as a programmable layer," says Adams. "The infrastructure is now there to be programmed."

The Smart Raman and analytics software is available and shipping in volume, says Ciena, while the photonic additions to the control plane are being trialled by customers and will be available in several weeks as part of the Release 10.0 software for Ciena's 6500 platform. 

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Ovum: Ciena launches WaveLogic Photonics, click here