Parametric processes are capable of preserving the phase information of optical signals while their frequencies are converted. This feature, in conjunction with other basic features such as instantaneous and wideband operation, low noise, and high reliability, creates various unique functionalities in optical domain, invaluable for realizing future dynamic all optical networks that are scalable in capacity without energy crunch. This paper will review the fundamentals and proof of concept of the parametric devices that authors have been proposing as important building blocks for the future networks. The devices to be reviewed are parametric wavelength converters, parametric tunable dispersion compensators, parametric delay dispersion tuners, and wavelength-tunable optical parametric regenerators.