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Path MTU Discovery

Medium

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MTU: every link has a maximum frame size

MTU (Maximum Transmission Unit) is the largest packet a link can carry without fragmenting it. - Ethernet: 1500 bytes - DSL/PPPoE: 1492 bytes (PPPoE overhead) - VPN tunnels: 1400–1460 bytes (encapsulation overhead) - Some legacy links: 576 bytes

If a packet is too large for a link, the router must either fragment it or drop it (if DF=1 is set).

Packets in motion — click to inspect:

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