We present a theoretical model and experiments to estimate and measure the magnitude of modal and chromatic dispersion interaction (MCDI) over multimode optical channels using vertical-cavity surface-emitting laser (VCSEL) based transceivers. The effects of MCDI and bit error rate performance are also evaluated for PAM-4 signals at data rates from 100 Gbps to 112 Gbps. A section of the article is dedicated to the characterization of the spectral coupling between VCSEL and fiber, including a multimode and a VCSEL with a dominant fundamental mode that has shown the potential to increase the reach of MMF channels. For the experiments, several types of OM4 and OM3 fibers, with accurate bandwidth characterization over a broad range of wavelengths were utilized. The reported analysis applies to future Ethernet and Fibre Channel applications requiring ≥100 Gb/s per wavelength over multimode fibers.