Thread

1. cube00 · 1790017251 · focus · HN ↗

   > When it went to flip into the backup, we discovered that the backup fiber had a break

   Pretty grim that a life critical system wasn't designed to report that the backup fibre was unserviceable until they attempted to switch over to it.

   I wonder how long it was down? Days, weeks, months?

   1. toast0 · 1790018021 · focus · HN ↗

      Sometimes your multiple fiber paths end up in the same bundle, severed by the same backhoe. It's always a fun day when that becomes apparent.

      1. unethical_ban · 1790020443 · focus · HN ↗

         That is negligence, practical if not contractual.

         Over ten years ago, my employer was spinning up a new DC across the state and had three links between it and the primary DC. Two were pretty direct, but we needed a third because at one point in the 300 mile path, the two main links went within 400 meters of each other.

         So how national-security-adjacent critical systems like an airport system doesn't have a larger set of backup links, and validates that they are geographically separate up until the connections, and have realtime alerting on the connection status, is surprising to me.

         1. bonestamp2 · 1790036428 · focus · HN ↗

            That is fascinating. Out of curiosity, how far apart would the paths have had to remain in order to be ok with just two links? Like, I'm thinking a plane crash between those two links in the 400m zone could destory both links so a third link makes sense, but if it were 800m that would probably be fine? Or what magnitude of disaster are they trying to mitigate and how much separation would that require for just two links?

            1. unethical_ban · 1790089994 · focus · HN ↗

               IIRC it also had to do with them passing near a railroad track, which they identified as an increased risk. So I'm guessing it is about perceived chance of risk - backhoes and groundwork are more likely near certain areas than there is of a plane crash.

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