EtherType is a field in the Ethernet frame, which indicates the protocol used in the data field of the frame. According to the IEEE 802.3, Length/EtherType Field is a two-octet field which takes one of two meanings, depending on its numeric value. For numeric evaluation, the first octet is the most significant octet of this field. When the value of this field is greater than or equal to 1536 decimal (equal to 0600 hexadecimal) the EtherType Field indicates the nature of the MAC client protocol (EtherType interpretation). The length and EtherType interpretations of this field are mutually exclusive.

The value of the Type Field is obtained from the IEEE EtherType Field Registrar. The EtherType Field is a very limited space and therefore its assignment will be limited. Only developers of new data transport protocols require an EtherType Field, whether or not they actually manufacture any devices. EtherType Field is administrated by the IEEE RAC EtherType Field Approval Authority for review and approval.

Well known protocols already assigned EtherType values. The commonly used values in the EtherType field and corresponding protocols are listed below:

EtherType: The Ethernet Type Field and Values

Related Terms: Ethernet, Ethernet Frame, EtherType, Ether Type, Ethernet Types

Reference Links: http://www.iana.org/assignments/ethernet-numbers: Ether Types