Kernaali ToolsHow it works
The model adds a 14-byte Ethernet header, four bytes per VLAN tag and four bytes of FCS. It pads to a minimum total frame of 64 bytes. Another 20 byte-times account for preamble/SFD and interframe gap.
Worked example
A 1500-byte IP packet with one VLAN tag makes a 1522-byte frame including FCS. Wire time corresponds to 1542 bytes; useful payload efficiency is about 97.28%.
Inputs, edge cases & common mistakes
Tags increase the L2 frame size, not necessarily the configured IP MTU. Some hardware preserves padding when inserting tags into an already padded frame; this tool models fresh framing with the selected tags. No LLC/SNAP, MACsec, PHY coding or FEC is included.
Technical references
Reviewed 9 September 2026. Found an issue? Send a correction with a reproducible example.