Leaping into the new year

With the addition of a leap second on December 31st, 2008 went on for a bit longer. This was interesting for me as we operate a pair of stratum-1 time servers, ntp1.heanet.ie (MSF-synched) and ntp2.heanet.ie (GPS-synched), both of which are in the ie.pool.ntp.org rotation. ntp2.heanet.ie maintained accuracy throughout, however ntp1.heanet.ie drifted by 1 second for a short while. This is to be expected however, as the MSF signal does not pre-announce the leap second.

Before Christmas, I began monitoring traffic to and from both servers in anticipation of some funky patterns in or around new years. We did get a surge of traffic, just not in the way I was expecting…

Days before and after the leap second

On new years eve, ntp2.heanet.ie suddenly became extremely popular – receiving 1.34Mbit/s of traffic at it’s peak. ntp1.heanet was slightly less in demand, spiking at 721.06Kbit/s. Both boxes reached their highest traffic levels since we put them into service at the end of November. However, from the graph it appeared that the traffic spike arrived several hours before midnight.

Total traffic at the leap second.

Drilling down, the largest amount of traffic was seen by ntp2.heanet.ie in or around 18:00 on the 31st with further spikes at 20:00, 21:30 and just before midnight. The only conclusion I can come to is that a large amount of people were frantically synching their clocks before heading out to the pub 😉

Further reading: Dave Malone collected quite a bit of information the last time a leap second appeared.