Wi-Fi Monitoring From Your Client's Eyes
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Travelers using free Wi-Fi in a busy airport terminal

Case Study

7SIGNAL Strengthens Wi-Fi Uptime for Millions of Airport Travelers at Major International Airport

The Problem

One of the busiest U.S. airports provides free Wi-Fi to hundreds of thousands of travelers and flight crews every month. Passengers turn to the Wi-Fi to download entertainment and communicate with friends and family while waiting to board their plane. Deplaning flight crews also tap into the free Wi-Fi to check schedule changes and work alerts.

“Our aim isn’t necessarily to have the fastest Wi-Fi; we want to deliver a network that’s always up and accessible,” says a senior staff engineer for the airport. “That’s no easy feat because there are many sources of network interference throughout the airport, including businesses and lounges we can’t control.”

“We have no legal or contractual authority to tell the airport’s tenants how to use their networks,” adds the engineer. “Some choose to work with us to help mitigate the interference, but when they don’t, we have to problem-solve.”

To quickly identify the source of connectivity issues, the airport’s IT team relies on 30 7SIGNAL sensors to validate the network throughout the concourse as well as the corporate network, which broadcasts the same APs disseminating the free Wi-Fi.

“The 7SIGNAL sensors are fixed and connected to our wired network. They can test the airport’s free network through different back-end pathways, including the wireless network, which runs over a separate ISP,” says a wireless network engineer for the airport. “With the Wi-Fi and network sensors, we look at and compare every element affecting connectivity.”

The Wi-Fi is ‘Broken’

The airport’s IT team says its primary concern with its free Wi-Fi is validating the service. If the DNS stops working, the team wants to know immediately. While the airport’s senior staff engineer always wants confirmation that the wireless APs are online and the controllers are healthy, he is most concerned with confirming users are successfully accessing Wi-Fi. For example, the signal might be strong, and passengers might connect and receive an IP address, but if DNS cannot resolve websites, users will perceive the Wi-Fi is broken.

“We move a lot of data to and from our ISP. We’re pushing 1.2 petabytes and have 10,000 clients on the Wi-Fi,” says the senior staff engineer. “Our numbers are like a university, but our clients change every hour unlike a college with repeating, individual clients.”

“We had other challenges,” adds the wireless network engineer. “Our Wi-Fi was terribly slow.”

There were times when devices would connect to the network and then suddenly lose their link to the AP. Another time, there was a connectivity issue at a single airline’s gates: as flight crews deplaned, they couldn’t connect to the airport Wi-Fi. “We struggled to figure out what was going on with this area,” recalls the senior staff engineer.

A Single Technology That Works Like 30 Technicians

Most connectivity issues at the airport get chalked up to Wi-Fi. But 7SIGNAL’s sensors have proven these issues often have nothing to do with Wi-Fi. With the 7SIGNAL sensors, the engineers can quickly probe what a user perceives as a Wi-Fi problem—and, in this case, they used that visibility to trace a passenger-facing outage back to a single misbehaving radio in a single access point, out of 1,200 across the airport.

The Solution

By connecting to the airport's free Wi-Fi and performing a DNS lookup, 7SIGNAL simulates what the traveler's device experiences. After connecting to a website, 7SIGNAL downloads the content and measures the total response time. Along with capturing the passenger's experience, the sensors see Wi-Fi connectivity, DNS resolution, gateway performance, ISP connectivity, and throughput. "We're validating that not so much on layer 1, but it's the back-end network and our connection to the ISP," says the airport's wireless network engineer.

While 7SIGNAL can monitor Wi-Fi RF metrics—AP transmission, radio signal availability, and signal strength—the team's concern goes beyond the radio layer. 7SIGNAL's value is in verifying that authentication services work, DNS responds, and passengers and crews can reach the internet. "We don't own the authentication, and if that's dragging, everybody 'sees' a Wi-Fi problem," says the senior staff engineer. "7SIGNAL's sensors help us address comments about the quality of our network."

Once the airport installed 7SIGNAL's agents and sensors, the team spotted a network issue no other vendor or manufacturer could find. Flight crews deplaning at one airline's gates couldn't connect to the free Wi-Fi. The team ran a report with 7SIGNAL's sensors and saw the AP was broadcasting, but clients weren't attaching. Armed with that data, the senior staff engineer opened a trouble ticket with the controller's manufacturer describing the bug.

7SIGNAL's sensors showed the AP stayed online—the 2.4 and 6 GHz radios worked fine—but the 5 GHz radio kept beaconing without accepting clients. The AP looked healthy because it was broadcasting. 7SIGNAL detected the problem because its sensors test the network from the user's perspective rather than just checking the infrastructure. The bug was shutting off the 5 GHz radio on one model of AP, installed in just one area of the airport where pilots and crews couldn't connect.

The Results

Having 7SIGNAL's sensors is like hiring approximately 30 technicians and deploying them across the airport to constantly report on the network and its 1,200 access points. "Without 7SIGNAL, we'd have to keep rebooting our APs and send techs to hover in different areas of the airport for days at a time to learn a particular radio isn't working," says the senior staff engineer.

With 7SIGNAL validating the full passenger experience—not just whether hardware is online—the airport can keep its network up and running and streaming fast enough that its Wi-Fi has been ranked among the industry's best for satisfaction.

With 7SIGNAL, we can keep the network up and running and stream fast enough that our Wi-Fi has been ranked among the industry's best for satisfaction.
Major International Airport,
Senior Staff Engineer