Network fails to start if VLAN have bigger MTU than default

[Martins Jakubovics]

Hello,

Looks like a bug for me.
If I configure interface VLAN with bigger MTU than 1500, which is default, interface with VLAN fail to start.

May 2 14:40:16 demo-host systemd[1]: Started ifup for eno3.1009.
May 2 14:40:16 demo-host sh[2184]: Set name-type for VLAN subsystem. Should be visible in /proc/net/vlan/config
May 2 14:40:16 demo-host sh[2184]: RTNETLINK answers: Numerical result out of range
May 2 14:40:16 demo-host sh[2184]: Failed to bring up eno3.1009.

auto eno3
iface eno3 inet manual
 mtu 1550

auto eno3.805
iface eno3.805 inet manual
        vlan-raw-device eno3
        mtu 1500

auto eno3.1009
iface eno3.1009 inet static
        vlan-raw-device eno3
        address 10.20.30.7
        netmask 255.255.255.0
        mtu 1550

eno3 and eno3.805 starts successfully, but eno3.1009 not. If I look at syslog, I can see, that interface boot order goes from last interface in config to first:

~# cat /var/log/syslog|grep -i "Started ifup for eno3"
May 2 14:40:16 demo-host systemd[1]: Started ifup for eno3.1009.
May 2 14:40:16 demo-host systemd[1]: Started ifup for eno3.805.
May 2 14:40:16 demo-host systemd[1]: Started ifup for eno3.

This is really strange, I suppose it should have some kind of order in such cases.
If I change configuration, e.g., eno3.1009 configure before eno3, host boots successfully with configured VLAN, but I suppose it could fail in some cases anyway.

So looks like we need some kind of "order" configuration in which we can setup after what cases we can take up interface.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

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[Sebastien Bacher (seb128)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. The issue you are reporting is an upstream one and it would be nice if somebody having it could send the bug to the developers of the software by following the instructions at https://wiki.ubuntu.com/Bugs/Upstream/GNOME. If you have done so, please tell us the number of the upstream bug (or the link), so we can add a bugwatch that will inform us about its status. Thanks in advance.

[Aron Xu (happyaron)]

@Martins, I want to know what's the MTU configured on eno3 interface, that one should be >= mtu of vlan interface.

[Launchpad Janitor (janitor)]

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