This paper evaluates the performance of slotted Optical Packet Switching (OPS) switching fabrics under self-similar traffic. The issue of how to synthesize a realistic self-similar traffic pattern for OPS networks is discussed. As a result, a methodology for designing self-similar batch sources suitable for OPS networks is proposed. Then, a buffering dimensioning study of the switching fabric is conducted under the proposed traffic model. Also, the variation in the self-similar traffic parameters suffered in the output process of the switch is evaluated and discussed.