Layer 2 Ethernet frame sizesΒΆ

The Layer 2 Ethernet frame as described here includes Ethernet headers, i.e. the CRC, but not the Inter Frame Gap, Preamble, or Start of Frame Delimiter (SFD).

The maximum frame size depends on the interface MTU (Maximum Transmission Unit); the default value is 1500 bytes.

The minimum frame size for IPv4 is 64 bytes, where the Ethernet header takes up 18 bytes, the IPv4 header 20 bytes, and the UDP header 8 bytes. The remaining 18 bytes are payload, where Paragon Active Assurance places a sequence number, a timestamp, a checksum, and a flow ID.

  • Minimum IPv4 frame size = 18 (Ethernet) + 20 (IPv4) + 8 (UDP) + 18 (payload) = 64 bytes

../_images/def-l2-eth-frame-ipv4.png

For IPv6 the minimum frame size is 84 bytes, since the IPv6 header is 40 bytes long.

  • Minimum IPv6 frame size = 18 (Ethernet) + 40 (IPv6) + 8 (UDP) + 18 (payload) = 84 bytes

../_images/def-l2-eth-frame-ipv6.png