What Is a Cable Landing Station?

By linking subsea cables to terrestrial networks, cable landing stations help make our connected world possible

Andy Castle
Nilesh Nawale
What Is a Cable Landing Station?

The world is becoming a more connected place, and we have subsea cables to thank for that. Any time you connect with other parts of the world over the internet—whether it’s to communicate with loved ones, shop from a favorite brand or stream global events like the Olympics—that data traffic almost certainly crosses subsea cables to reach you. In fact, you may even have accessed this very blog post via subsea cables.

The way these cables move data across vast oceans in mere milliseconds is an engineering marvel, but it wouldn’t count for much without a way to reliably get that traffic to end users on dry land. This is where the cable landing station (CLS) comes into play. A CLS is simply any facility where a subsea cable terminates on land. This may sound obvious, but when you look at how a subsea cable terminates, things get a bit more complicated.

What happens inside a cable landing station?

Subsea cables are made up of two distinct components: a copper conductor tube to carry electrical power to submerged active components along the cable, and an optical fiber that provides long-distance data transmission. A CLS houses equipment that terminates the cable and each of its components:

  • Cable termination equipment (CTE) terminates the subsea cable and separates the power and fiber lightguide paths.
  • Power feed equipment (PFE) terminates the copper conductor. The PFE is essential because subsea fiber optic cables longer than 500 kilometers—which includes most intercontinental crossings—use undersea optical repeaters to boost signals and keep traffic moving over long distances. Those repeaters need a reliable power supply, and that’s what the PFE provides by converting battery power to a constant current of up to 1.0 amp at variable high voltages.
  • Submarine line terminal equipment (SLTE) terminates the optical fiber. It’s the first step in extending data traffic from the intercontinental subsea network to the domestic terrestrial network. To put it simply, subsea cable traffic can’t reach end users without going through a data center first, and it can’t reach the data center without terminating at an SLTE.

The CLS also provides the space, power and cooling needed to keep the PFE and SLTE running. Recent events have shown how reliant we’ve become on subsea cables; even short outages can lead to digital bottlenecks that interrupt our everyday lives. Thus, it’s very important for cable landing stations to have on-site power infrastructure connected to a stable energy grid with battery and generator backup.

The diagram above shows the infrastructure that connects the subsea cable to the CLS, including the marine steel directional bores and the beach manhole. The cable operator is responsible for building and maintaining this equipment, including getting all the necessary permits. Collectively, this equipment makes up the fronthaul network.

In contrast, the backhaul network connects the CLS to data centers further inland. The length of the backhaul determines how quickly data traffic can reach end users, which means there’s great value in ensuring a quick, efficient backhaul.

What are the different types of cable landing stations?

In the past, there was typically only one variety of CLS. It was built and operated by traditional telco providers; therefore, operators who landed cables in these facilities were locked in to using the telco’s backhaul network.

More recently, the trend has been toward open, carrier-neutral cable landing stations. This is the model we use at Equinix. When we open a CLS, we invite other backhaul providers to deploy in our facilities. This encourages competition to provide the best backhaul performance possible. The result is that traffic reaches the terrestrial network quicker, benefiting both service providers and end users.

CLS inside a data center

Some facilities are built to serve as both cable landing stations and data centers. This means the backhaul is removed altogether, avoiding the latency and inefficiency that would otherwise occur.

The Equinix MI3 IBX® data center in Miami serves as a CLS for subsea cable systems connecting the U.S. with Brazil. Since there’s no need to build a dedicated CLS separate from the data center, the owners and operators of the cable (consortium members) benefit from lower costs and simplified deployment in a state-of-the-art facility.

The cable users benefit as well. Since Equinix data centers are multitenant and vendor-neutral by design, there’s a host of enterprises, cloud on-ramps and service providers inside Equinix MI3 waiting to take advantage of the interconnection opportunities the cable offers. Since they can do that with no backhaul, the data traffic gets to end users quicker.

Modular CLS

While the benefits of a combined data center/cable landing station are clear, not all locations are a good fit for such a facility. A location would need to:

  • Be in a metro that’s dense enough to support a multitenant colocation data center but also close enough to the coast to serve as a CLS.
  • Be protected against natural disasters and supported by a stable power grid.
  • Have a coastline free from possible blockers like commercial shipping ports and fishing activity, protected national marine sanctuaries and habitats, and rocky seabeds that could damage cables.

In locations that can’t meet all these criteria, a CLS separate from the data center may be the best choice. They can be built quickly and efficiently using a modular deployment with a smaller physical footprint and lower demand for energy. A typical design for such a facility uses two prebuilt containers, stacked one on top of the other or side by side. One container hosts the power infrastructure, while the other hosts the termination equipment.

Equinix used a modular design to build our Equinix BX1 facility in Bordeaux. It now serves as the cable landing station for a cable system connecting France with the U.S. Thus, we’re helping to make Bordeaux a hub for transatlantic cable traffic. Along with the Equinix BA1 facility in Barcelona and GN1 in Genoa, BX1 provides an alternative to more crowded landing sites in the Mediterranean subsea cable corridor.

Equinix supports optimized cable landing stations

As we look toward the future of subsea cables, we can safely say that it will involve more cable systems landing in more places. That’s why it’s so important to have a global provider working to build advanced, open cable landing stations wherever they’re needed. Equinix is well positioned to be the global CLS partner that achieves the best results for both cable operators and cable users.

For instance, ensuring sustainable subsea cable networks is a growing area of concern. As a sustainability leader in the data center industry, Equinix can help with this. Since subsea cables draw power from the CLS, landing them inside clean, efficient data centers is among the best ways to make them more sustainable.

In 2023, we achieved 96% renewable energy coverage across our global data center portfolio. Many of the Equinix data centers that double as cable landing stations—including the Equinix LA4 Los Angeles IBX data center where subsea cables connecting to South America and transpacific routes land—are covered by 100% renewable energy.

Learn more about the Equinix approach to distributed digital infrastructure and how it enables the free flow of data—both through cable landing stations and data centers further inland. Read our vision paper, The future of digital leadership.

 

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Andy Castle VP, Global Networks Planning & Implementation
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Nilesh Nawale Principal Network Architect
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