Methods for configuring an optical link in which a distribution of transmission data rates and line rates are configured for a predetermined amount of optical bandwidth to maximize transmission capacity. In these methods, a controller of an optical network obtains input parameters that include a signal-to-noise ratio (SNR) for optical signals and an allocated bandwidth of the optical link, further obtains, for each line rate, a mapping of transmission data rates along a frequency spectrum of the allocated bandwidth compatible with the SNR, and generates a channel plan in which a number of traffic modes and a distribution of a plurality of channels in the allocated bandwidth are set to maximize transmission capacity. The plurality of channels is used for transmitting the signals on the optical link. The controller configures at least one optical network element in the optical network to establish the optical link based on the channel plan.