Date: Mon, 4 Apr 2022 09:27:02 +0200 From: "Patrick M. Hausen" <hausen@punkt.de> To: freebsd-net@brettglass.com Cc: "freebsd-net@freebsd.org" <freebsd-net@FreeBSD.org> Subject: Re: Wireguard, MTUs, and jumbo packets Message-ID: <A696BF9A-6048-4CB2-9731-3B8BF90FCE2A@punkt.de> In-Reply-To: <202204040337.VAA10654@mail.lariat.net> References: <202204040337.VAA10654@mail.lariat.net>
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Hi all, > Am 04.04.2022 um 05:37 schrieb freebsd-net@brettglass.com: > 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. >=20 > 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. [Interface] PrivateKey =3D ************** Address =3D [...] DNS =3D [...] MTU =3D 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. HTH, Patrick --=20 punkt.de GmbH Patrick M. Hausen .infrastructure Kaiserallee 13a 76133 Karlsruhe Tel. +49 721 9109500 https://infrastructure.punkt.de info@punkt.de AG Mannheim 108285 Gesch=C3=A4ftsf=C3=BChrer: J=C3=BCrgen Egeling, Daniel Lienert, Fabian = Stein
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