A programmable packet switching controller has a packet buffer, a pattern match module, a programmable packet classification engine and an application engine. The packet classification engine has a decision tree-based classification logic for classifying a packet. The application engine has a number of programmable sub-engines arrayed in a pipelined architecture. The sub-engines include a source lookup engine, a destination lookup engine and a disposition engine, which are used to make a disposition decision for the inbound packets in a processing pipeline.