[atlas] Paris-traceroute variations

>>> Each interval, it will try one variation. So if you select 16
>>> variations then it will take 16 intervals before you get back to the
>>> first one.
>> i think that, as we showed in [0], 16 may be low for typical paths.
>> [0] - https://ripe66.ripe.net/presentations/128-130513.tokyo-ping.pdf
> In that presentation I cannot find any clear evidence that that there
> are more than 16 unique paths. But maybe I missed something.

apologies.  i guess it was in the paper not the preso, uppr right of
page 3 of

  C. Pelsser, L. Cittadini, S. Vissicchio, and R. Bush, From Paris to
  Tokyo: On the Suitability of Ping to Measure Latency, 2013 Internet
  Measurement Conference.
  <http://conferences.sigcomm.org/imc/2013/papers/imc125s-pelsserA.pdf>

the intuition is that it is a function of the richness of the path
diversity.

perhaps a tunable?

randy