Ethernet frame Preamble 56 bits of alternating ls and Os SFD Start field delimiter, flag(10101011) Destination Source Length Preamble SFD address address PDU Data and padding CRC 7 bytes 1 byte 6 bytes 6 bytes 2 bytes 4 bytes CSIE NTUT TANAN Figure 3-4CSIE, NTUT, TAIWAN 12 Figure 3-4 Ethernet Frame