The two layers in a network packet that identify its content (for details about layers, see TCP/IP and OSI model). The bottom layers 1, 2 and 3 are the protocols that move a network packet from source to destination. Layers 4 and 7 identify the application that created the packets as well as the specifics of the request. For example, inspecting layer 4 can identify HTTP traffic (Web traffic), but inspecting layer 7 can determine what the HTTP request is for (see Web switch). See layer 4 switch and well-known port.TCP/IP SWITCHING/ROUTING DECISIONSLayer and ForwardingProtocol DecisionInspected Based on 2 - Ethernet MAC address 3 - IP Network address 3 - IP Service quality 4 - TCP/UDP Traffic type socket (HTTP, FTP, etc.) 7 - HTTP HTTP request type.