OSI Open Interconnection Reference Model
Seven
Layer 1 Physical Layer
Original bit stream transport machinery, electronics, communication channel timing interface
Explanation: First, to solve communication needs between the two physical machines, machines A ---> B transmits the bitstream machine
(Standard defines the physical layer is mainly a physical device, such as the type of cable, the interface, an optical fiber transmission bit stream (0/1) is converted to the current strength, the destination, and then converted to machine code 0/1 (NIC at this level))
NIC
Layer 2 Data Link Layer
Physical addressing, while the original bit stream into logical transmission line
Layer 3
Operation control subnet addressing logic, packet transmission routing