Re: Wireguard, MTUs, and jumbo packets

From: Patrick M. Hausen <>
Date: Mon, 04 Apr 2022 07:27:02 UTC
Hi all,

> Am 04.04.2022 um 05:37 schrieb
> Would like to use the new Wireguard implementation, but need to know what it does to MTUs. I'd like a full 1500 byte MTU through the VPN tunnel, but this means that the packets that are sent between the client and server have to be BIGGER than 1500 bytes.
> It takes a special feature to allow PPPoE to negotiate a larger MTU (see RFC 4638), and other PPP-based protocols such as L2TP wont do it at all. But what happens in Wireguard? I can find no documentation on this topic, so assistance would be appreciated.

as far as I know WireGuard does not care about interface or PMTU
nor perform PMTUd. You can set the WG interface MTU in the configuration, e.g.

	PrivateKey = **************
	Address = [...]
	DNS = [...]
	MTU = 1280

Wether your path will be capable of transporting packets with a tunnel MTU
of 1500 is left for you to take care of - outside of WG.

WireGuard overhead is 60 bytes for IPv4 transport and 80 bytes for IPv6.

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