The ON2020 panel session at OFC this year, titled "Industry Visions for a Converged Optical Networking Roadmap," provided a fascinating insight into the challenges faced by a diverse set of network operators and highlighted some of the technologies that will be required in future optical networks.

Some key themes were shared by the various operator executive presenters, including: growing bandwidth demands driven by cloud services, network cloud applications, autonomous vehicles, IoT and 5G wireless; the need for massively parallel networks and low-latency connections; and requirements for modular building blocks supported by an open ecosystem.

ON2020 is an IEEE Industry Connection (IC) program that is working to ensure the industry identifies the requirements for optical networks from 2020 onward and develops the right roadmaps and deployment scenarios. Free from near-term thinking competition and standards constraints, ON2020 is helping to set longer-term goals and directions for optical networking. ON2020 is open to anyone interested and the group is calling for participation from across the optical networking industry. The ON2020 panel session at OFC included speakers from Microsoft Azure, BT, Deutsche Telekom, Facebook and China Telecom. The session was moderated by ON2020 Chair Peter Winzer from Nokia Bell Labs and Xiang Liu from Huawei, who asked the speakers to offer their visions for the future of optical networking.

Mark Filer, optical network achitect at Microsoft Azure, explained the Microsoft regional architecture with distributed data centers and long-haul connections between regions. Filer expects that from 2021, 100G PAM4 connections will be needed to servers, likely replacing copper DACs (direct attach cables) with AOCs (active optical cables), and data center switch networks will require connection speeds beyond 400G. Solutions for these higher-speed connections may include on-board optics based on COBO, optics in package, and optics on die. Intra-data-center connections will move to 400G ZR (a simplified, low-cost standard for Ethernet connectivity) during the next three to five years, and will require 1.6Tbit/s links from 2023. Filer believes long-haul connections will use flexible solutions based on technology already available, or in development, and sees a need for open line systems that support long-haul interoperability.

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Andrew Lord, head of optical research at BT, presented a vision with a deep fiber 5G access network, a metro transport network with 25G direct detect and cheap 100G coherent connections with many wavelengths, and a photonic core that supports more than 10 Tbit/s per fiber. Lord believes these networks will need to be autonomous and self-healing, providing dynamic bandwidth on demand and quantum-based security. The photonic core will need parallel fibers, C + L and other bands, and the whole network will need to support SDN setup for E2E services and dynamic 5G slices.

Deutsche Telekom's Arnold Mattheus explained that the German operator's current network consists of an IP backbone connecting through aggregation rings to an access network. This network needs to evolve with greater capacity, lower latency for 5G, and support for automation, disaggregation and brownfield upgrades. Mattheus views current open networking solutions as a disaster, due to today's vendor silos, and believes the way forward is through a common optical controller controlling open line systems from different vendors.

Chengliang Zhang, vice president of China Telecom Beijing Research Institute, showed data traffic increasing 11 times by 2025, driven by many applications, including 5G, IoT and 4K/8K video with support for VR and AR. Zhang sees 400G commercial application starting in 2018, with massive application from 2021. Long-distance connections require trade-offs between distance and bandwidth and will require support for C + L bands and superchannels. Zhang explained that a universal network is needed at the edge, providing one service that supports all applications and connections. Zhang concluded that this network would support growing bandwidth, combine ROADM and wavelength-switched optical network (WSON) functionality and provide a cost-optimized, multiservice solution. (See An Optical Transport Vision for the Cloud, 5G Era.)

Katharine Schmidtke, an optical technology strategy executive at Facebook, sees coherent looking good for longer distances and expects optics to replace DACs for short links in data centers. Schmidtke expects that a key development in the data center will be the integration of photonics and switching. This can be achieved by mounting photonic, electronic and switch dies on a common substrate. These photonically-enabled ASIC solutions move the optics on board, removing the requirement for pluggable optics on the front panel, reducing power, overcoming signal integrity limits and enabling better reliability. Schmidtke believes these solutions should be designed for scale and reliability, and supported through open solutions and ecosystems, including OCP and TIP.

During this ON2020 session at OFC, the speakers shared their visions for optical networking. There were many common themes, all of which require innovation and new optical networking developments within data centers, between data centers, into the access network, and, as ever, over long-distance connections. Through ON2020, the industry has the opportunity to define the future requirements for optical networks and to work with leading manufacturers and open forums to ensure that they can deliver on these roadmaps.

Follow this link for more information about the IEEE ON2020 IC program and the OFC 2018 session.

— Simon Stanley, Analyst at Large, Heavy Reading

This article is sponsored by ON2020.