By Brian Lavallée, Senior Director, Solutions Marketing at Ciena

Much has changed in the past 159 years since the first subsea cables delivered telegraph communications. These cables have been laid upon seabeds around the world, stitching together continental landmasses and resulting in the largest manmade construction feat ever created by size – the Internet. Subsea cables have gone from a relatively successful, albeit very low-speed telegraph communications medium, to today’s high-speed critical infrastructure. These cables now carry hundreds of terabits of data each second, over thousands of kilometers in the harshest environments on earth on glass strands no larger than a human hair. How can one not be impressed by this engineering marvel we use every day?

When Ciena was founded in 1992, the World Wide Web hadn’t even been born yet, but the evolution of submarine cables and networks since then has been immense, turning them into one of the most critical pieces of infrastructure in the modern world. From the advent of coherent networking to the rise of predictive analytics and maintenance, the technologies surrounding submarine networks are advancing ever rapidly, leading us toward new challenges and opportunities every day.

To celebrate this year’s 25th anniversary of Ciena, I would like to reflect on some of the notable trends and milestones that have impacted submarine networking since the company was first established. Here are several of the key developments that have changed, and continue to change, the submarine networking industry and, consequently, the entire connected world:

The Dawn of Coherent Networking

While it has only come within the last decade, coherent technology is one of the most significant advancements to submarine networks over the past 25 years. By allowing higher data rates (100 Gb/s and higher vs. 10 Gb/s) to be sent over extremely long-haul networks spanning thousands of kilometers, this enhanced performance and flexibility breathed new life into existing subsea assets by making it possible to transport significantly more information on the same fiber.

Planet of the Internet Content Providers

The bandwidth consumption boom of Internet Content Providers (ICP) presents a new set of challenges to traditional carriers in the modern networking landscape. Not only are ICPs generating the vast majority of data traffic today, but they are also putting it on their own cables in key regions, which is changing the industry’s entire business model. It is staggering to think that 60 percent of the transatlantic bandwidth going over submarine cables is produced by the data centers of a handful of ICP companies who are essentially talking to themselves. What’s more, that number was non-existent a decade ago. These data centers have completely changed the face of submarine networks as we know it.

Networks Open Up

For a variety of historical, political, geographic, and technological reasons, submarine networks were proprietary turnkey network solutions – in other words, closed. Over the past few years, with the advent of coherent detection modems originally developed for long-haul terrestrial networks, all that is changing.

Once these coherent modems were successfully tested across a 3rd party submarine cable, it became possible to upgrade wet plants deployed a decade or more earlier, from 10G (and sometimes even lower) to 40G and 100G, and even higher. This has allowed submarine cable operators to increase the capacity of their undersea assets to greatly extend the life of their investment, without having to lay costly new cables for quite some time.

The open movement is impacting submarine networking by aiming to remove the proprietary nature from networks to allow network operators to choose best-in-breed technologies from a much broader selection of vendors. Gone are the days of closed and proprietary submarine cable networks. The benefits and possibilities offered by open networks create new business opportunities through a transformational change in how networks are designed and operated.


Today, submarine cables carry more than $10 trillion worth of transactional value, each and every day. Over the last few years, Ciena and other vendors have focused intently on upgrading cables and being able to cram as much data as possible into new cables. However, the focus is now shifting towards determining how to best protect these capacity upgrades. It’s one thing to lose a few Gb/s of traffic, it’s quite another thing to lose multiple Tb/s of traffic!

There should be a healthy dose of concern associated with the threat of cable faults. While traffic can be rerouted to a new cable, that cable, and available capacity, must already be in place to maintain the flow of critical data communications. Today, cables are increasingly being pushed to full capacity with few alternative paths available to serve as backup. Were a major earthquake to happen in the wrong area, it could result in massive, wide-scale outages impacting entire continents. Fortunately, forward-looking cable operators are well-aware of the implications of cable cuts and are addressing these concerns via cable resiliency and diversity.

Shannon’s Limit Approaches

Submarine cables deployed years ago are today supporting a major increase in total information-carrying capacity. The exact total capacity of an upgraded cable depends upon its unique performance personality, but all capacity increases are astounding. Such cable upgrades have brought new life into existing subsea wet plants, some more than a decade old, and allow cable operators to maintain pace with over 40 percent CAGR in bandwidth demand in all regions of the world.

The introduction of coherent Submarine Line Terminating Equipment (SLTE) was a sea change milestone in the industry, with operators getting used to massive increases in capacity their subsea assets could support. However, there’s a looming limit to how many bits can be crammed into an existing optical fiber, known as the Shannon Limit – the hard, physical limit of how much data can be crammed onto a single fiber in the presence of noise. There are modem-centric advances and new wet plant designs that represent opportunities to challenge Shannon’s Limit, directly and indirectly, so it’s not all doom and gloom.

Analytics and Predictive Maintenance

Submarine cables have not been exempt from the big data and analytics adoption and the benefits they have brought. Most components of submarine networks show warning signs over time before they ultimately fail, and one of the biggest advantages of open northbound APIs is the ability to extract, consolidate, and analyze network data coming from the subsea network elements. They offer a variety of timely network performance and health data such as polarization mode dispersion, chromatic dispersion, transmitter power levels, receiver power levels, losses, bit error rates, and more. Much of this information is already being used to prevent, or at least minimize, the “miserable” days in the life of a submarine field technician. Proactive, predictive maintenance gives cable operators the opportunity to fix network faults before they occur and ultimately reduce network downtime.

Make Way for the Autonomous, Self-Driving Network

Who better to tell us about our networks’ health than the network itself? Imagining a scenario where our networks talk, tell us they are about to fail somewhere in the network, and decide to reroute traffic to prevent outages may sound like science fiction, but we are already close to this level of interaction with our networks. In fact, some of these capabilities are available right now, and the reason is the emergence of big data analytics, machine learning, and eventually, full-blown artificial intelligence in the future as the technology matures over time.

What started as a journey to be a hopeful technology provider for the cable industry, has led us to our current position as the leader in the submarine cable upgrade market. We have seen profound technological advancements and we are more connected now than ever before. Now we also have the ability to not only care for our networks but are close to giving them the ability to care for themselves. The future of our industry won’t be achieved through some major upgrade, but rather via a journey where we help our networks become the trusted partners we need them to be. To get there, as with any human relationship, the interface between us and them must also evolve as they get smarter and increasingly autonomous. Are you ready for the future?