Stack protocol headers inside an IP MTU budget. Watch what's left for payload. When overhead exceeds the limit, the bar turns red — that's exactly the moment packets get dropped in real networks.
▼Paste output from mtu-inspect-linux.shoptional — auto-fills stack from your Linux host
Script source is at the bottom of this page.
WIRE FRAMEwhat runs on the cable between this host and the next hop
IP PACKETwhat's inside the IP region above, expanded — what travels end-to-end
▼Readout
Link MTU
IP MTU as reported by ip link
Overhead (L3+)
0 B
Payload
1500 B
TCP MSS
—
Wire frame size
1514 B · IP MTU + L2 framing
Total bytes on the cable. Compare to your switch's port MTU.
▼Diagnostic
L3 and above
counted in IP MTU
L2 framing
on the wire, not in MTU
Add layer
Presets
▶mtu-inspect-linux.sh — sourcerun on a Debian/Linux host, paste the output above
Read the script before running it. It only prints to stdout — nothing is sent anywhere.