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MTUMulti-Platform
Stack up tunnel/encapsulation overhead to see what link MTU you need to carry a given payload without fragmenting — and what to actually configure on Cisco IOS/IOS-XE, IOS-XR, Junos, Arista EOS, and Fortinet FortiOS, since their mtu command doesn't mean the same thing on every platform. Need to check whether two vendors will actually interoperate on a QinQ trunk? See the VLAN / QinQ Tag Overhead Calculator.
Desired End-to-End Payload
bytes (the original IP packet size you need to survive the whole path)
Tunnel / Encapsulation Overhead (reduces available payload for a given link MTU)
L2 Framing (doesn't touch the IP payload budget — only affects platforms whose
mtu includes the L2 header, below)Provided as-is, with no warranty of any kind. This runs entirely in your browser as a convenience tool, not a certified reference — always double-check results before relying on them for anything important, especially production changes. See the full disclaimer.