  We evaluate the generation of the cross-channel interference (XCI) for
coherent transmission through a variety of dispersion-managed segments in a
disaggregated optical network framework, using split-step Fourier method (SSFM)
simulations and an implementation of the Gaussian noise (GN) model. We observe
that the small inline residual dispersion remaining after each span affects the
accumulation of the XCI, causing GN model predictions to no longer be
conservative. We find an asymptotic upper bound to this additional
accumulation, providing a worst-case prediction, and observe that this depends
upon the residual dispersion within the link. This upper bound scales similarly
to the self-channel interference (SCI) accumulation, and is well characterized
by the parameters of the underlying fiber spans and the transmitted signals.
