The Luna Quarterly

Duplex fiber patch cords are elemental in the high-speed data center industry, yet their manufacturing process creates a challenge for certain high-end users. These cords are used where communication between devices requires a separate and simultaneous transmit-and-receive, leading most to assume that the two fibers inside the cable are the same length. This is not the case, however, as manufacturing processes and variances often leave one fiber longer than the other. As a result, there can be a slight variance in assumed versus actual time of flight.

While this difference in fiber length is insignificant for most data centers and network operators, the discrepancy could have huge implications in certain markets. When dealing with financial trading data centers, for example, every last picosecond counts: duplex fiber cord discrepancies could ultimately affect their place in line to make a trade, potentially costing traders millions of dollars. How then do you accurately measure the length of a cable that is hundreds of meters long with multiple connector junctions when you only have access to one end of the fiber?

Luna has created a solution to the discrepancy in time-of-flight between transmit and receive for our customers in the high-speed data center industry.  Luna’s OBR products measure every fiber link in the data center and around the campus as a function of nanoseconds or meters.  By measuring every fiber, not just one fiber of each pair, it is possible to know whether the transmit time-of-flight and the receive time-of-flight are the same, close enough to not matter, or different enough that they need to be accounted for.