Deep Packet Inspection

Deep packet inspection (DPI) is a key technique for packet classification. Information transmitted over the Internet is divided into packets, which are composed of the headers in various layers and the payload. Packet headers provide information such as source addresses and destination addresses for assisting packet transmission, while packet payloads carry application protocol messages. Network devices typically classify the incoming packets and determine how to process them according to preconfigured rules that associate actions with the classification results. The actions include, to name a few, dropping, logging, forwarding, and policing. Conventional devices such as switches and routers inspect only packet headers to determine how to process the packets (e.g., forwarding a packet to a certain output port according to its destination IP addresses). DPI means ...