documentclass{article}

usepackage{pgf}
usepackage{pgfplots}

pgfplotsset{compat=1.8}

usepackage{tikz}
usetikzlibrary{arrows,automata,calc,shapes, positioning,shadows,shadows.blur,shapes.geometric}

begin{document}
begin{tikzpicture}
begin{axis}
addplot[thick,line cap=round,rounded corners, draw=red,double=white,double distance=1.6pt,fill=white, blur shadow={shadow yshift=-5pt, shadow xshift=3pt,shadow blur radius=3pt}
] table {
dof l2_err level
.2 2.6 2
%.3 2.8 3
.4 2.3 4
.5 2.4 5
.6 1.1 6
.7 1.8 7
.8 4.6 8
.9 3.3 9
1 6.2 10
};
end{axis}
end{tikzpicture}
end{document}