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US halts flights at busy East Coast airports, says fiber line cut

239 points · 150 comments · allanbreyes

  1. atonse · · focus · HN ↗
    I don't quite understand this sort of thing happening. Wasn't the whole point of the internet to be a self-healing network where we route around severed cables, etc?

    Or is it that these ATC networks are their own air-gapped network with less redundancy? That just doesn't add up. Or maybe there was only one line going to the ATC, with no multiple "ISPs" like a datacenter would have?

    1. bri3d · · focus · HN ↗
      * Yes, TRACON have their own dedicated links. You can look into ASTERIX and STARS to learn some of the cursed ways the data processing and dataflow work.

      * There is supposed to be a primary and a secondary link, in this case the primary failed and the fail-over also failed. It's unclear from the reporting if they were damaged in the same incident or if the failover was not tested or monitored adequately.

      The Philadelphia TRACON site has been notoriously unreliable and was supposedly improved in 2025, it's also unclear if these issue actually could stem from that implementation.

      1. wrs · · focus · HN ↗
        I’ve had enough double-redundant links fail - and I mean pretty thoroughly double-redundant, different provider, different media, different physical path - that I’m quite surprised something like the air traffic control system only has two links.
        1. Polizeiposaune · · focus · HN ↗
          Contractually dual-path, or actually dual-path? My understanding is that there's enough infrastructure horse-trading going on behind the scenes that it's very difficulty to be certain that two circuits between points A and B don't share the same infrastructure somewhere in between.

          First big oops of this form that I remember:

          "In December 1986, the ARPANET had 7 dedicated trunk lines between NY and Boston, except that they all went through the same conduit -- which was accidentally cut by a backhoe. "

          <a href="https:&#x2F;&#x2F;www.csl.sri.com&#x2F;~neumann&#x2F;insiderisks06.html" rel="nofollow">https:&#x2F;&#x2F;www.csl.sri.com&#x2F;~neumann&#x2F;insiderisks06.html

          1. FireBeyond · · focus · HN ↗
            Yup. Seven different paths comes with seven different sets of equipment, and seven different rights-of-way that have to be negotiated, purchased, leased, whatever.
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