\documentclass{article}

\usepackage{tikz}
    \begin{document}
  \begin{tikzpicture}
  \draw  [<->,  line width=1pt]   (0,0.5) .. controls (.5,1.5) and (2,1.5) .. (2.5,0.5);
   \node  (v1) at (0,0) {1};
    \node  (v2) at (2.5,0) {1};
\end{tikzpicture}
\end{document}