Ethernet - Frame Format

Frame Format

• 64-bit/8-byte preamble - allows receiver to synchronize with the signal
• 48-bit/6-byte destination MAC address
• 48-bit/6-byte source MAC address
• 16-bit/2-byte type - identifies to which of the many higher-level protocols this frame should be delivered to
• N-bit data body - between 46 to 1500 bytes of data
• 32-bit/4-byte CRC - Cyclic Redundancy Check (CRC) for error detection

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• like HDLC protocol, Ethernet is a bit-oriented framing protocol
• frame size (including preamble) must be between 72 to 1,526 bytes
• network adaptor’s perspective: sender attaches the preamble and CRC, receiver removes them
• host’s perspective: frame has a 14-byte header (two 6-byte address and a 2-byte type field) and a N-bit body