Structure
A data packet on the wire is called a frame and consists of binary data. Data on Ethernet is transmitted most-significant byte first. Within each byte, however, the least-significant bit is transmitted first.
The table below shows the complete Ethernet frame, as transmitted, for the payload size up to the MTU of 1500 octets. Some implementations of Gigabit Ethernet (and higher speed ethernets) support larger frames, known as jumbo frames.
| Preamble | Start of frame delimiter | MAC destination | MAC source | 802.1Q tag (optional) | Ethertype (Ethernet II) or length (IEEE 802.3) | Payload | Frame check sequence (32‑bit CRC) | Interframe gap |
|---|---|---|---|---|---|---|---|---|
| 7 octets | 1 octet | 6 octets | 6 octets | (4 octets) | 2 octets | 42–1500 octets | 4 octets | 12 octets |
| ← 64–1522 octets → | ||||||||
| ← 72–1530 octets → | ||||||||
| ← 84–1542 octets → | ||||||||
Read more about this topic: Ethernet Frame
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