Re: Wireguard, MTUs, and jumbo packets
- In reply to: freebsd-net_a_brettglass.com: "Wireguard, MTUs, and jumbo packets"
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Date: Mon, 04 Apr 2022 07:27:02 UTC
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. > > 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 = ************** 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. HTH, Patrick -- 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 Geschäftsführer: Jürgen Egeling, Daniel Lienert, Fabian Stein