Autumn 2021 - Optical Connections Magazine


CAPACITY OPTIMISATION And how about capacity optimisation, are organisations successfully achieving it or are they simply throwing in more bandwidth to satisfy their needs? Nokia’s Larrigan says on this, “Optical network operators face growing capacity demands and the cost of addressing these requirements can significantly impact their bottom line. With the introduction of SDN (software-defined networking) optical networks will see increased client port speeds and more dynamic service requests. “For network operators, the challenge is to extract maximum efficiency and bridge the gap between where their networks are today and where they need to be in the future.” Advances in coherent wavelength modulation formats, together with Colorless Directionless Contentionless - Flexgrid (CDC-F) wavelength routing, are enabling new approaches to optical network optimisation, says Larrigan. “Rather than defining beginning-of-life network infrastructure based on worst- case, end-of-life fibre infrastructure parameters, operators can use real-time network data within a continuous ‘learn and optimise’ approach that adapts to approaching end-of-life conditions,” he says.

The idea is that operators can use applications to periodically tune the network to maintain optimal performance and availability and stay ahead of deteriorating network conditions. When end-of-life conditions eventually threaten network performance, the application can make proactive network re-optimisation recommendations before they impact service deployment velocity, resulting in a more robust and adaptable network. Homa from Ribbon said, “The benefits of MLO have always been clear, with the potential to produce five-year capex savings from 15% to 60% depending on how deeply it uses shared resources for restoration. But until recently this has been difficult to implement practically because of the algorithmic and control complexity. What is happening now is a two-pronged approach. Organisations are continuing to increase bandwidth capacity since new technologies like 400G ZR+ allow them to do so economically, and they are also beginning to adopt aspects of MLO because new SDN tools are now making this possible,” said Homa. AUTOMATION Automation is arguably key, are there serious attempts in the market already to address the above issues,

to correlate alarms at multiple levels - service, wavelength, link etc. - to effectively identify the root cause. “The way to accommodate PM in this increasingly complex environment is the NMS (network management system) software, which needs to not only be dimensioned to handle more services, but also to provide an intuitive user-interface to enable simplified fault

management,” Crenn added. Ribbon’s Homa concluded,

“Enigmatically, fault management is becoming both more complex and easier to execute. Complexity is added if we want to consider the full impact of a fault on all layers of the network, not just an isolated, single optical layer or IP layer. But today’s advanced software tools automate many of the processes involved with fault management such as fault identification and localisation, service and network restoration for increased ease.” Homa said, “Multi-layer optimisation is an important tool in the restoration toolkit, but the network must be designed in such a way that it doesn’t end up with fault restoration processes in the IP layers being in a race with restoration processes in the optical layer - that can easily cause network instability.”


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| ISSUE 25 | Q3 2021

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