Spectral-amplitude-coding (SAC) is a widely spread coding scheme in optical access networks such as optical code-division multiple access (OCDMA) and radio-over-fiber (RoF). This talk introduces the packet processing methods of switching and buffering over optical core networks based on SAC labels. Efficient services of route determination and contention resolution are achieved as time- and power-consuming optic-electronic-optic (OEO) conversions in the conventional schemes are not required. The packet structures with various types of SAC labels, the detection algorithm of label identification, the codec design for label generating/processing, and the derivation of the performance measures are covered. SAC technique enables the network nodes to provide fundamental operations on optical packets with low system cost and complexity.