EtherType is the Ethernet Type/Length field value that identifies the protocol carried inside a frame. Values of 1536 or greater indicate an encapsulated packet type; values of 1500 or less indicate packet length. section 6.2.3 section 6.6
Recognizing IPv4 and IPv6
An EtherType of 0x0800 (2048 decimal) identifies IPv4, while 0x86DD (34525 decimal) identifies IPv6. Values between 1500 and 1536 should not be used. section 6.2.3
Use these thresholds when interpreting an Ethernet frame:
- 1500 or less: interpret the field as the encapsulated packet length in bytes. section 6.2.3
- 1536 or greater: interpret the field as EtherType identifying the encapsulated packet. section 6.2.3
