The problem
A fiber optic ticket had been open for more than 20 days, well past SLA. Data center technicians (DCTs) couldn’t resolve it because they couldn’t locate the far end switch (FES): the port in question on the near end switch (NES) had no label. The only information available for the FES came from the system of record — asset ID, serial number, and port number — with no indication of where in the data center it physically lived.
The mission
Locate the FES within a large-scale data center and confirm whether the fiber was actually broken. The FES could be anywhere: same row, a different row, any position.
The actions
The first step was to go physically to the NES and gather whatever information was available on site. From there, the approach was to check the closest neighboring switches of the same model to see if their ports were labeled. A few were, which made it possible to trace those neighbors to their own FES and look for a pattern.
The first pattern that emerged was that FES were located at the beginning or end of rows, on racks labeled EVEN or ODD — never in the middle. That narrowed the search considerably, but the data center still had many EVEN and ODD racks to check one by one. Repeating the same exercise on each new data point narrowed the pattern further: first to EVEN racks only, then to EVEN racks in the last rows, and finally to the specific rack unit (RU) where the FES had to be. Following that narrowing pattern led directly to the switch.
The find was confirmed by scanning the FES’s asset ID and serial number and matching them against the system of record.
Result
Beyond locating the FES, a simple visual fault locator (VFL) test confirmed the fiber was indeed broken. Knowing the fiber distance between the NES and FES also made it possible, per standard operating procedure, to identify the right team to run a new long-haul LC-to-LC fiber.