A、The main task of the physical layer is to ensure the correct transmission of the bit stream through the transmission medium
B、The transmission media connecting physical layer may have different types, such as optical fiber and wireless communication lines, etc.
C、Protocols of physical layer can be divide into two types: point-to-point communication lines and broadcast-based lines
D、Physical layer shields the difference between Ethernet and IP
喵查答案:Physical layer shields the difference between Ethernet and IP