8 octets |
6 octets |
6 octets |
2 octets |
varies |
4 octets |
Preamble |
Destination |
Source |
Type |
Payload |
CRC |
Table 5.12: Structure of an Ethernet frame
The ``preamble`` of an Ethernet frame consists of seven octets of ``10101010`` followed by a single
octet of ``10101011``. The purpose of the ``preamble`` is to declare to a device intends to send a
frame and to synchronize the other devices to listen as receivers. The destination and source
addresses are 48-bit (6-octet) :term:`media access control (MAC) addresses