In this work, we study an asynchronous optical packet/burst switching node equipped with a number of limited range wavelength converters shared per output link. A wavelength conversion policy is one by which the outgoing wavelength for an optical packet is selected if its incoming wavelength is in use. Through simulations, we show that the so-called "far conversion" policy in which the optical packet is switched onto the farthest available wavelength in the tuning range, outperforms the other policies we studied. We point out the "clustering effect" in the use of wavelengths to explain this phenomenon.