Steve Grubb, Ph.D., a key member of the Global Optical Architecture team at Facebook, is a telecoms industry veteran with close to three decades of experience in building the world’s communications networks.

Facebook’s corporate mission is “to give people the power to build community and bring the world closer together” by focusing on empowering people, enabling community building, and connecting the world. In order to build a global social network that addresses these three corporate goals, a physical network that interconnects user content must be available – overland and undersea. The latter is the focus of Facebook’s global submarine cable investments, which is the foundation of a social networking platform.

Brian Lavallée, Senior Director of Submarine Network Solutions Marketing at Ciena, sat down with Steve Grubb to discuss recent activities that took place on its transatlantic MAREA submarine cable network.

Why is Facebook investing heavily in so many new submarine cables around the world?

Facebook now has 3.1 billion users worldwide that use one of the Facebook family of apps once or more monthly. The majority of these users are outside of North America.  Hence, we require significant amounts of bandwidth on inter-continental submarine fiber cables. 

Can you tell us more about Facebook’s transatlantic MAREA submarine cable and why it was built?

MAREA was the first open submarine cable that Facebook was involved with from start to finish.  MAREA is used to communicate with users and data centers outside of the USA.

Figure 1: MAREA submarine cable from Virginia Beach (USA) to Bilbao (Spain) (ref: TeleGeography)

What were the goals of the recent trial with Ciena on MAREA and were your expectations achieved?

Facebook has and continues to invest in submarine cables around the world. We constantly strive to maximize the return on our investments in these global submerged assets. Part of this includes maximizing the optical spectral efficiency of our wet plants and is why we tested Ciena’s WaveLogic 5 Extreme technology. We also wanted to investigate how software can potentially improve the overall spectral efficiency by leveraging embedded instrumentation in Ciena’s WaveLogic family of coherent optical modems.

There’ll always be a requirement to physically install equipment into racks and connect fibers between ports, so this process is near impossible to fully automate. However, we do believe there are significant gains to be had by intelligently automating the optical spectrum activation process. We were satisfied with the results, as we saw tangible benefits in the time it took to enable the spectrum of channels, as well as improvements in spectral efficiency on this Open Cable design.

What benefits does intelligent data-driven automation bring to Facebook and to your customers?

In any deployment, you have to physically install equipment, activate optical spectrum, and then test it. We believe there are significant gains in the second and third parts of this process from an intelligent automation perspective. Moreover, when Facebook and others are investing in Open Cables and qualifying a vendor’s maximum capacity on these cables, a test kit is typically deployed, and measurements taken over time to qualify each fiber pair. This process is quite time-consuming and often requires additional trial equipment that can be challenging, especially in these trying times of travel restrictions. If such capabilities are embedded directly in SLTE products, we can more easily get a very accurate picture of the achievable cable capacity, which saves significant amounts of time.

The automated configuration algorithm Ciena tested with us leverages the embedded Signal-to-Noise (SNR) monitoring parameters from the WaveLogic modems to provide insights into overall cable capacity and avoid the need for additional physical test kit to qualify the cable. Turning up modems to a default mode guaranteed to work on any cable system, and then determining real-time system margin, allows for the modem and photonic layer provisioning to be updated automatically to rapidly optimize the channel’s capacity.

Facebook is investing in several submarine cables all over the globe. Some landing sites are in locations that are easier to access while others are in more challenging locations. Nonetheless, we require capacity to be delivered on the promised date, regardless of site complexities. Intelligent data-driven automation allows us to rapidly and reliably scale our required capacities.

How has COVID-19 affected Facebook from a submarine network perspective? 

Facebook strives to intelligently automate all of our networks. COVID-19 has only accelerated our need to automate our global network. Countries with varying quarantine mandates further exacerbate this new dynamic. Even with such challenges, we still need to deliver the required capacity, as bandwidth demand continues to grow unabated.

Considering worldwide stay-at-home mandates related to COVID-19, how important is remote testing, troubleshooting, and channel turn-up to Facebook?

COVID-19 introduced complexities and challenges that we all must live with for the foreseeable future. For example, we’ll need to comply with ongoing travel restrictions. Therefore, we must be able to add new capacity remotely, using intelligent data-driven automation, and ensure this automation achieves the maximum capacity on our submarine cable assets. At Facebook, we’re working on advanced machine learning-based algorithms and expect the systems we deploy to follow similar design philosophies.

What do you see as the future of submarine cables for Facebook and for the industry in general?

We’ll continue to build submarine cables to meet our increasing capacity demands. Increased efficiencies in turning up and optimizing submarine cable capacity are desired so that we can scale our processes.