Fryguy's Blog Back to Tools
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, and Arista EOS, since their mtu command doesn't mean the same thing on every platform.
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)