We investigate both theoretically and experimentally the stochastic switching between two
counter-propagating lasing modes of a semiconductor ring laser. Experimentally, the residence time
distribution cannot be described by a simple one parameter Arrhenius exponential law and reveals
the presence of two different mode-hop scenarios with distinct time scales. In order to elucidate
the origin of these two time scales, we propose a topological approach based on a two-dimensional
dynamical system.