• Today’s rapidly evolving landscape of use cases that demand highly performant and efficient network infrastructure is placing new emphasis on how in-line amplifiers (ILAs) are designed and deployed.
• Meta’s ILA Evo effort seeks to reimagine how an ILA site could be deployed to improve speed and cost while making a step function improvement in power efficiency.

Over the past year, Meta has been on a journey to reimagine fiber optic in-line amplifier (ILA) sites. An important piece of network infrastructure, ILAs  serve to amplify optical signals and are often placed in remote locations between data centers. If one ILA fails, an entire intercity route fails, and if one ILA cannot grow, the entire fiber route is constrained. Meta is excited to introduce new ideas and concepts to help modernize the ILAs for tomorrow.

To that end, we’ve launched the ILA Evo effort to overcome the historic design constraints of today’s ILAs, namely:

• The minimal skilled labor and raw material required at the deployment site;
• The requirement that buildings meet local snow, wind, and seismic load along with fire codes and health and safety regulation –  plus lifespan greater than 25 years; 

This new effort seeks to propel advancement through several new requirements: 

• Requiring the building and inside plant (ISP) must be deployed in three to four days.
• Reducing the need for specialized heavy equipment (avoiding the cost and time for heavy-lift cranes to travel to a remote site).
• Minimizing concrete (avoid cost and time to transport, form, tie rebar, pour, and cure concrete).
• Reducing the power usage effectiveness (PUE) to less than 1.5 – nowhere near Meta’s operational data center PUE average of 1.09 (2023 average), but an achievable and significant improvement.

A short history of ILAs

Fiber optic cable networks have seen exponential growth in both size and capacity since GTE launched the first fiber optic network in 1977. U.S. network operators would install 20,039 mi (32,250 km) of intercity fiber routes by 1985. This would quadruple to 83,618 mi (134,570 km) by 1989 and double again to 159,779 mi (257,149 km) by 1998, with MCI, Sprint, USTelecom, and WilTel being the major players in those early days.

As fiber was rolled out along roads, railways, and pipelines, real estate to house optical signal repeaters was developed in parallel. What later became known ILA sites were spaced 18 to 25 miles (30 to 40 km) apart. With rapid improvements in both optical fiber purity and composition, plus advancements in optronics, spacing soon doubled into the 50 to 60 mile (80 to 100 km) range where it has largely remained until today.

Early ILA building designs were roughly modeled on Bell Telephone central offices, albeit a shrunken down version: concrete shells (or stick framed construction on a steel I-beam base) placed atop concrete foundations; wall-mounted HVAC units; -48V power distribution; lead-acid batteries; diesel backup generators and so forth surrounded by chain link fences. 

Buildings were constructed in a central location with ISP fitted into the shell before shipment to the site (via specialized motor carrier) and placed with a heavy-load crane. However, unlike the remarkable (and ongoing) advancements in fiber and optronics (e.g., CWDM to DWDM to Coherent DWDM), ILA sites themselves have received little attention.

Today’s ILA buildings are often larger, with more efficient HVAC systems. Components like security and building access systems have been modernized, but if you dropped a field technician from 1990 into one of today’s ILAs, they’d have little difficulty navigating. Historically, ILA sites haven’t required significant evolution, however newfound capacity growth and innovation has warranted the development of new ILA approaches.

The structure of ILA Evo

Working with global engineering consultancy AECOM, we’ve organized the problem and our engineering efforts into several categories: different building systems and foundations; a new ISP installation method; alternative ballistics protection; introducing more efficient cooling; and modernizing backup power systems.

Building system

Identify lightweight building designs which can be flat packed for easy, quick shipment and unloaded at the deployment site using a lift gate. Our emphasis has been on buildings composed of fiberg