In optical transport networks that use 2R optoelectronic wavelength converters, performance degradation is expected due to the accumulation of timing-jitter. We theoretically analyze the effects of timing-jitter and the cascadability of 2R optoelectronic wavelength converters based on a nonlinear signal model. We measured the cascadability in a 40-km re-circulation loop for 10 Gb/s signal.