Time for sovereignty
From vision to practice: satellite-free, terrestrial source added to TimeNL
At SIDN Labs, we’re constantly working to further enhance the reliability of TimeNL, our NTP and NTS-based public time synchronisation service. A key feature of our vision for the service is to reduce reliance on global navigation satellite systems (GNSS), such as GPS and Galileo. We recently took an important step in that direction, introducing 2 new TimeNL servers that receive their time signals directly from the source via a fibre-optic network.
Why we’re looking beyond satellites
Time synchronisation is of fundamental importance to the internet. Indeed, it’s a key infrastructural component. Most of the world’s time servers rely on GNSS signals, because atomic clocks aren’t for everyone, and GNSS-based time synchronisation is a low-threshold alternative with many attractive features.
However, while GNSS signals are extremely accurate, they’re also vulnerable. They can be affected not only by atmospheric disturbances, but also by active interference, such as jamming (signal-blocking) and spoofing (sending fake signals). For a vital infrastructure, being dependent on such signals constitutes a risk.
Back in April 2022, therefore, we presented our plan for a more resilient TimeNL, utilising a mix of time sources in order to mitigate that risk. A year later, in April 2023, we published a follow-up article calling for an even more reliable internet time infrastructure that doesn’t depend on satellite systems.
A terrestrial, sovereign alternative
In that article, we urged people to help build a time infrastructure based on time signals received not only by air, but also via surface-based (terrestrial) fibre-optic systems connected to officially traceable atomic clocks. Where the Netherlands is concerned, that implies connecting to, for example, the National Metrological Institute VSL in Delft.
We have since been working to turn our vision into reality – by, for example, discussing our ideas with network operators, research centres, internet hubs and others, including AMS-IX.
AMS-IX makes a conspicuous move
AMS-IX recently announced the launch of a satellite-free time service that gets its time from VSL via a fibre-optic connection. Their time-as-a-service approach feeds reliable time into the network exactly where digital infrastructures meet, and reduces dependency on external satellite systems. It’s therefore a big step forward, which is very much in line with the plans we previously outlined. We also see it as confirmation that the need for terrestrial, traceable time is steadily gaining acceptance.
TimeNL adds GNSS-free time synchronisation
Less conspicuously, but with similar intent, we’ve been working here at SIDN Labs to realise the vision of a time service that isn’t reliant on GNSS. At our Nikhef-hosted facility in Amsterdam, we now have 2 new, experimental NTP servers available:
ntppool3.time.nl ntppool4.time.nl
Both servers are GNSS-free. They receive their time signal, UTC(VSL), from the VSL’s official atomic clocks in Delft via a fully terrestrial fibre-optic link utilising the SURF Time & Frequency network. The two new public NTP servers also support the Network Time Security (NTS) protocol, so that not only the accuracy of the time signal, but also its authenticity is assured.
Formally speaking, the servers’ status is currently still ‘pre-production’, since we want to make the set-up more resilient, as we’ve done with our existing servers. However, they’re live and available for experimentation and evaluation.
A shared vision becomes reality
By taking this step, we’ve shown that a time infrastructure that doesn’t depend on satellites, but utilises national time references, is no longer a futuristic notion.
Our additional service increases the resilience of the Dutch internet infrastructure. TimeNL users can now take advantage of a time signal whose source is on Dutch territory and is accessed via local fibre-optic connections.
Redundancy and diversity make time synchronisation more resilient, just as they make the internet itself more resilient. While we are not suggesting that GNSS should be replaced, we believe that the availability of alternatives can only be beneficial, and we wish to contribute to development of the ecosystem where we can. Various organisations in the Netherlands and other parts of Europe are making similar moves, each finding their own solution, but all guided by a shared fundamental vision: time (synchronisation) has to be a first-class, resilient component of the internet.
Everyone is invited to try out our new servers. Your feedback will help us to keep perfecting TimeNL.
