Passive Optical LAN Technology is Paving the Runway for Airport Modernization and Sustainability

In a September 2022 speech, President Joe Biden called attention to the fact that the U.S. currently has no airports that rank in the top 25 in the world. He also reaffirmed the administration’s commitment to improving U.S. airports as part of the multi-billion dollar infrastructure bill passed last year. Technology is a crucial part of that commitment.

In today’s digital world, an airport cannot function without faultless, high-bandwidth connectivity for the myriad of systems critical for day-to-day operations, security and passenger experience — from airline ticketing and baggage handling to security screening, digital signage, paging and gate management. With the International Air Transport Association (IATA) expecting global passenger travel to expand substantially over the next two decades, reaching nearly 8 billion passenger journeys per year by 2040, technology becomes even more crucial. Several major U.S. airports are now turning to highly resilient passive optical local area networks (LANs) as the foundation to support that technology.

Going the Distance Without Disruption

Airports differ physically and operationally from other enterprise campuses and facilities. An airport terminal comprises a central headhouse for ticketing, baggage claim and security screening that connects to a series of concourses with multiple gates, restaurants, retail shops, lounges and various other facilities. Unlike a typical campus building constructed of stacked floors, each concourse is like a skyscraper placed on its side that must accommodate as many gates as possible and where tenant space is at a premium. That leaves limited real estate for multiple controlled and secure IT spaces required in a traditional network architecture.

With the ability to support various speeds, systems and services on one infrastructure, passive optical networks have a long history as a service provider architecture for bringing connectivity to cities and subdivisions. Over the past few decades, this approach has made its way into enterprise LAN environments, with particular advantages for airports.

“In an airport, I can eat, shop, and catch a flight — it’s like a little city within itself,” says Al Lyons, director of IT and electronic systems for HOK, a global design, architecture, engineering and planning firm that designs airport terminals and transportation hubs. “Many airports have built several separate networks over the past 50 years to support a wide range of systems, but there are advantages to moving them all over to one passive optical LAN.”

A passive optical LAN comprises centrally managed optical line terminals (OLTs) connecting to optical network terminals (ONTs) throughout an airport using single-mode fiber optic cable and passive optical splitters. Each ONT offers multiple network ports to connect and power devices. With fiber's distance and bandwidth capabilities, a passive optical LAN can span 20 kilometers (12.5 miles) or more between OLTs and ONTs, eliminating the need to deploy multiple traditional IT spaces with switches, power and cooling throughout the airport headhouse and concourses.

“A passive optical LAN represents huge savings in terms of equipment, hard construction costs, space and energy with no need to build out multiple IT spaces that occupy expensive real estate and require active equipment, power, and cooling,” says Lyons.

Airport owners, operators and airlines also need to have confidence in the technology. For one major international airport upgrade, HOK and leading IT services provider ConvergeOne allocated six months during the construction schedule to build an off-site test facility where they converged multiple systems over a passive optical LAN to prove its feasibility.

“We were able to demonstrate that a passive optical LAN can handle different services from multiple providers and allocate different speeds for different tenants,” explains Nick Vermeer, solutions architect for ConvergeOne.

During upgrades, airport terminals must remain fully functional for passengers. The fiber comprising a passive optical LAN can handle relatively harsh environments, allowing the network to traverse construction areas and be deployed early during a project to transition over various networks and services.

Operating with Resiliency and Reliability

While a passive optical LAN reduces the need for IT spaces in terminals, airports also demand faultless connectivity with the highest network availability and security levels to maintain real-time services. In a passive optical LAN, ONTs have no local user interface and do not store information locally. Instead, they are controlled and configured by the OLTs, eliminating thousands of unsecure touch points on the network and preventing misconfigurations.

“In a traditional network, we have to configure secure encrypted links to devices and between switches, which requires expensive, sophisticated orchestration software. With a passive optical LAN with built-in encryption between OLTs and ONTs, you just enable it in the centralized management platform,” says Vermeer.

Unique to Tellabs OLTs deployed at several major U.S. airports, built-in monitoring within an OLT also improves resiliency by monitoring for failures of card-level components, memory faults, traffic and communication. In the event of a network failure, OLTs with this capability enable immediate fail-over and/or card swapping to ensure uninterrupted traffic flow. It also allows for replacing a failed card without affecting network availability.

“We prefer to design airport networks with OLTs that offers built-in monitoring and fail-over. This capability allows us to service every splitter feed by a different OLT card — similar to connecting copper cabling to separate switches in a traditional architecture but with much better and cost-effective protection,” says Vermeer. “With a centralized management platform, we can also visualize the entire network from one location, which significantly eases maintenance rather than the ‘let’s find the bad switch hunt’ that is all too common with traditional networks.”

Passive optical LANs also deliver higher levels of resiliency for airports using standards-based protection with geographically dispersed OLTs, dual splitter feeds and fiber route diversity for complete redundancy. Referred to as Dual-Parented Type B PON protection in ITU-TG.984.1 standards, this configuration connects the two feeds from each splitter to separately located OLTs. If one OLT is rendered out of service, the other takes control. The system's design can also use a diversification approach where certain ONTs connect to separate splitters based on location and application.

“We constructed two separate main computer rooms with complete PON protection for one major airport. During construction, a water pipe broke, which took out an OLT. No one even noticed because everything immediately flipped over to the other OLT,” says Lyons.

 Delivering Sustainability for the Future

In addition to providing a resilient and reliable technology infrastructure, passive optical LANs help airports improve sustainability and meet increasingly stringent energy efficiency objectives.

“With a passive optical LAN, space and energy savings can be quantified. Right off the top, it eliminates a sizable portion of IT space that house large stacks of power-hungry active equipment, which also all requires cooling,” says Joel Fischer, sales engineer for Tellabs. “With one small hybrid copper-fiber cable to ONTs that provides multiple ports, rather than running traditional large copper cables to every port, the overall amount of pathway space and material that comprises the technology infrastructure is also significantly reduced.”

The unlimited bandwidth of single-mode fiber with transmission rates limited only by the electronics also provides a more futureproof, sustainable technology infrastructure. As technology evolves, only the active endpoints need refreshing. “If you look at traditional switched network infrastructure, it lasts only about 10 to 15 years. The advantage of a passive optical LAN with single-mode fiber is that it won’t need to be replaced over the lifetime of the airport, which eliminates disruption and offers huge lifecycle savings,” says Lyons.

Passive optical LANs deployed at airports around the country are now supporting everything from the latest ticketing, baggage and gate management systems to security, signage, paging, retail point of sale, Wi-Fi and passenger entertainment. The future-proof and sustainable nature of passive optical LANs also facilitates the implementation of emerging technologies, such as new scanners with sophisticated 3-D imaging and algorithms to detect weapons, explosives, and other prohibited items that the TSA is rolling out. Passive optical LANs are also ideal for supporting future technologies like machine learning, artificial intelligence and autonomous vehicles that will further improve ground handling, aircraft maintenance, building operations, resource monitoring, security, crowd control, and traveler experiences.

With the average age of U.S. airports at 40 years, President Biden’s infrastructure bill granting billions for airport improvements across the country, and the global air transport industry committing to reaching net zero carbon emissions by 2050, passive optical LANs are proving to be an ideal technology infrastructure that will help make airline travel safer, more accessible, more efficient, and more sustainable.