What Data Looks Like on an Ethernet Network

An Ethernet frame has a 14 byte header, a data section, and a 4 byte trailer.

Ethernet header contains the address of the machine that should read the frame, the address of the machine that sent the frame, and the Ether Type

Ether Type is used to indicate which protocol is encapsulated in the payload of an Ethernet Frame.

0800 – IPv4, 0806 – ARP, 8035 – RARP, 8600 – IPv6

802.1Q tag

The IEEE 802.1Q tag is an optional 4-octet field that indicates Virtual LAN (VLAN) membership and IEEE 802.1p priority.

Payload Data

The minimum payload is 42 Bytes when 802.1Q tag is present and 46 Bytes when absent and the maximum payload is 1500 Bytes. Non-standard jumbo frames allow for larger maximum payload size

Frame check sequence (CRC)

The frame check sequence is a 4-octet cyclic redundancy check which allows detection of corrupted data within the entire frame.