MTU settings not always applied after reboot

Bug #1630191 reported by Dr. Jens Harbott on 2016-10-04
This bug affects 2 people
Affects Status Importance Assigned to Milestone
ifupdown (Ubuntu)

Bug Description

On a node with two 10G interfaces, we configure a bond interface from these two interfaces and then a vlan interface on top of it. The MTU of these interfaces shall be set to be 1550 instead of the default 1500, so we have these settings in /etc/network/interfaces.d:

root@controller-node13:~# cat /etc/network/interfaces.d/xge0
auto xge0
iface xge0 inet manual
  bond-master xiondata

root@controller-node13:~# cat /etc/network/interfaces.d/xge1
auto xge1
iface xge1 inet manual
  bond-master xiondata

root@controller-node13:~# cat /etc/network/interfaces.d/xiondata
auto xiondata
iface xiondata inet manual
  bond-slaves xge0 xge1
  bond-miimon 100
  bond-lacp-rate 1
  bond-mode 4
  mtu 1550

root@controller-node13:~# cat /etc/network/interfaces.d/xiondata.200
auto xiondata.200
iface xiondata.200 inet static
  vlan_raw_device xiondata
  mtu 1550

After a reboot, the correct MTU is applied to the vlan interface only 50% of the time, on the other attempts, it stays at 1500, leading to broken connectivity. If I restart the interfaces manually, by doing "ifdown xiondata; ifup -a" the MTU settings seem to be applied correctly every time.

root@controller-node13:~# apt policy ifupdown
  Installed: 0.8.10ubuntu1
  Candidate: 0.8.10ubuntu1
  Version table:
 *** 0.8.10ubuntu1 500
        500 xenial/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ifupdown 0.8.10ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-38.57-generic 4.4.19
Uname: Linux 4.4.0-38-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Tue Oct 4 09:44:40 2016
 PATH=(custom, no user)
SourcePackage: ifupdown
UpgradeStatus: No upgrade log present (probably fresh install)

Dr. Jens Harbott (j-harbott) wrote :
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in ifupdown (Ubuntu):
status: New → Confirmed
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