EXFO ETS-1000 - Manual (Page 147)

Ethernet Tester Analyzer 139
B Ethernet Frame Structure
Ethernet Frame Structure

Destination MAC Address: 6 bytes field that contains MAC address of
the destination network node.

Source MAC Address: 6 bytes field that contains MAC address of the
frame source network node.

Length/Type: The field contains 16-bits integer and possesses either of
the following values:

If the contained number is less than or equal to 1500, then the
value is set to Length and defines the length of the data field.

If contained number is more than or equal to 1536, then the value
is set to Type value and specifies type of the used protocol.

Data: Data field can contain from 46 or 42 (in the case of a frame with
VLAN-tag) to 1500 bytes.

Pad: If the data field is less than 46 bytes then the containing frame is
complemented to the minimum allowed length (64 bytes) with the
padding field.