Deep inspection (DI) is another vendor favorite. Most vendors’ IDS/IPS product lines support Layer 3 through 7 inspection. Deep inspection is just another way of saying that the device does more than just stateful inspection of Layer 4 sessions. DI is the analysis of packets at higher layers using patterns in traffic such as excess fragments as well as string patterns in application transactions. Just remember that
vendors will apply whatever terminology is most advantageous to them.