As metropolitan (metro) transport networks grow from 2.5-generation (2.5G) services to 10G and eventually 40G, the underlying optical systems need to compensate for the lower chromatic dispersion tolerances on the 10G and 40G interfaces. In optical networks, the dispersion compensation unit (DCU) compensates for accumulated chromatic dispersion effect in fiber. It provides a flexible solution for accumulated chromatic dispersion without dropping and regenerating the wavelengths on the link, a process that would otherwise be necessary when accumulated chromatic dispersion exceeds the maximum allowed dispersion tolerance.