From 874a47238040d5e970beb96f510a38cd398e5f41 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?St=C3=A9phane=20Graber?= Date: Thu, 15 Feb 2024 22:56:08 -0500 Subject: [PATCH] doc/faq: Add mention of the -mtu network interfaces MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Stéphane Graber --- doc/faq.md | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/doc/faq.md b/doc/faq.md index 8882fa677db..ab6dc75297e 100644 --- a/doc/faq.md +++ b/doc/faq.md @@ -109,3 +109,10 @@ The easiest fix for this problem is to stop the VPN client and unmount the `net_ If you need to keep the VPN client running, mount the `net_cls` cgroup1 in another location and reconfigure your VPN client accordingly. See [this Discourse post](https://discuss.linuxcontainers.org/t/help-help-help-cgroup2-related-issue-on-ubuntu-jammy-with-mullvad-and-privateinternetaccess-vpn/14705/18) for instructions for Mullvad VPN. + +## What is this `incusbr0-mtu` device? + +When setting the `bridge.mtu` option on an Incus managed bridge network, Incus will create a dummy network interface named `BRIDGE-mtu`. +That interface will never be used to carry traffic but it has the requested MTU set to it and is bridged into the network bridge. + +This has the effect of forcing the bridge to adopt that MTU and avoids issues where the bridge's configured MTU would change as interfaces get added to it.