  We present the results of an analysis of data collected by IceCube/DeepCore
in 2010-2011 resulting in the first significant detection of neutrino
oscillations in a high-energy neutrino telescope. A low-energy muon neutrino
sample (20-100 GeV) containing the oscillation signal was extracted from data
collected by DeepCore. A high-energy muon neutrino sample (100 GeV -10 TeV) was
extracted from IceCube data in order to constrain the systematic uncertainties.
The non-oscillation hypothesis was rejected with more than $5\sigma$. We fitted
the oscillation parameters $\Delta m^2_{23}$ and $\sin^22 \theta_{23}$ to these
data samples. In a 2-flavor formalism we find $\Delta m^2_{23}=
(2.5\pm0.6)\cdot10^{-3}$ eV$^2$ and $\sin^22 \theta_{23}>0.92$ while maximum
mixing is favored. These results are in good agreement with the world average
values.
