Stage 1 → PPPoE

MTU/MRU Calculator for PPPoE and VLAN

Make PPPoE overhead visible before you troubleshoot slow pages, broken VPNs, or selective connectivity.

Free to use · Runs locally in your browser · Last reviewed 2026-09-26
Review before deployment: The result is an engineering starting point. Path MTU, VLAN tags, tunnels, and provider equipment can add overhead that a local calculator cannot observe.

Inputs

mtu-mru-result.txt
Change an input to recalculate.
How to use this result
MTU is the largest IP packet size that should cross the path without fragmentation. MRU is the largest packet the PPP peer agrees to receive. The calculator subtracts the overhead you specify and suggests a conservative MSS for IPv4 TCP; it does not replace a real DF-bit path test.
/ping 1.1.1.1 size=1464 do-not-fragment=yes
Increase or decrease the payload until the largest repeatable value is known, then compare it with the configured PPPoE and tunnel values.
Related tools
PPPoE + RADIUS GuideUnderstand PPPoE overhead, profiles, and testing.


Sources and safe-use notes
This page follows the RouterOS documentation and the networking standards linked below. RouterOS syntax, hardware limits, and packet direction depend on your exact release and topology. Export a backup, test one controlled case, and keep a rollback path before applying generated output.
MikroTik documentation · RouterOS manual · RFC 4632 — CIDR · RFC 6598 — shared address space · RFC 8200 — IPv6 · MikroTik PPP documentation · RFC 879 — TCP maximum segment size