The Finnish Metrology Institute MIKES has set up a White Rabbit link between two PCs that are connected with a 1000 (one thousand!) kilometer link. This work is a collaboration between MIKES and CSC - IT Center for Science Ltd that operates FUNET (the Finnish University Network.

The White Rabbit console reports a mean round-trip-time (RTT) delay of 10.4 ms with a daily variations of ca +/- 40 ns.
10.4 ms corresponds to a ca 2000 km round trip, assuming a refractive index of 1.5.
The WR protocol is compensating for the daily variations, but this could not yet be verified as both points are physically spaced at a 567 km driving distance.

This is a first step to evaluate WR for comparison and synchronization of geographically distant atomic clocks in the White Rabbit time-transfer experiment between Espoo and Kajaani in Finland (pdf).
The next step is to verify the accuracy of the transferred white-rabbit timebase by moving a Cs-clock and a GPS receiver to Kajaani in the near future.

“Wow, this is AWESOME”, was the comment of Tom Wlostowski, designer of the first WR hardware, while Maciej Lipinski, co-chair of High Accuracy sub-committee of the extension/revision of the IEEE1588-2008 standard wrote: “This is getting really CRAZY”.

This experiment shows that the White Rabbit hardware and protocols are much more flexible than the original design goal for use at maximum distance of ten kilometer. Also the fact that the designs are “Open”, made that MIKES could easily replace the original SFP lasers by longer reaching types.