The disclosed embodiments relate to a system that provides an intelligent port infrastructure for communication network devices. This is accomplished by incorporating a highly configurable pre-classifier module into the port infrastructure. This pre-classifier makes it possible to realign packet data to add a configurable number of bytes to the front of the packet, and also to select interesting data from incoming packets for further analysis. The selected data is sent into a configurable classification engine, which generates instructions that specify how to determine associated packet attributes. The packet attributes are then generated based on the instructions, and are forwarded along with the packet to downstream processing units.