Ethernet Frame Fields

• Preamble - seven bytes of alternating 0s also 1s to notify receiver of incoming frame and to provide synchronization
• SFD (Start frame delimiter) - one byte signalling the beginning of the frame
• DA (Destination address) - six bytes containing the physical address of the next destination if packet must reach another LAN this field contains the physical address of the router upon reaching the target network field then contains the physical address of the destination device
• SA (Source address) - six byte field containing physical address of last station to forward packet sending station or most recent router

• Length or type - Two bytes indicating number of bytes in coming PDU if fixed length can indicate type
• Data - 46 to 1500 bytes
• CRC - CRC-32 error detection information