EtherType is a two-octet field in an Ethernet frame that indicates the protocol type of the payload (the data contained within the frame). It’s part of the Ethernet frame header used by the network layer for packet demultiplexing. EtherType values are assigned and maintained by the Institute of Electrical and Electronics Engineers (IEEE).
- IPv4: The EtherType for IPv4 is 0x0800. This indicates that the payload contains an IPv4 packet.
- IPv6: For IPv6, the EtherType is 0x86DD. This signifies that the payload is an IPv6 packet.
Comparing EtherType to other similar terms
EtherType can be compared to an IP packet’s Type of Service (ToS) field. While EtherType describes the protocol type of the payload in the Ethernet frame, ToS specifies the priority of the IP packet.
Advantages and disadvantages of EtherType
- Packet demultiplexing: It allows the network layer to identify the payload protocol, ensuring data is correctly processed.
- Limited range: The EtherType field can only accommodate a finite number of protocol identifiers, which can limit its usage.
Tips for understanding EtherType
- Each EtherType corresponds to a specific protocol. Familiarize yourself with common EtherTypes to better understand network packet data.
- Use packet analysis tools like Wireshark to examine EtherTypes and better understand network traffic.