This paper presents an experimental demonstration of the Linear-Least Squares Longitudinal Power Monitoring (LLS-LPM) technique over a mixed fiber link. The link is made by five spans, including four spans of G.652 Single-Mode Fiber (SMF) and one span of G.655 Non-Zero Dispersion-Shifted Fiber (NZDSF) with negative dispersion in the C-band. The study highlights the challenges posed by the negative dispersion of G.655 fiber and its impact on the convergence of the LLS-LPM algorithm. The experimental results demonstrate that the LLS-LPM algorithm can accurately estimate the power profile in the portion of the link where the cumulated chromatic dispersion is unambiguous. This work provides valuable insights into the application of LLS-LPM in real-world fiber networks with mixed fiber types.