[Bug 1224007] Re: mtu not always set properly on bond/vlan interface
Robie Basak
1224007 at bugs.launchpad.net
Tue Oct 11 15:17:36 UTC 2016
Uploaded, thanks! I appreciate the high quality changelog entry.
I modified the Xenial version to 1.9-3.2ubuntu1.16.04.1 since
1.9-3.2ubuntu1 also exists in Vivid and Wily. Otherwise we'd have to
work around not having something less than 1.9-3.2ubuntu1.1 available in
case of an SRU to Vivid or to Wily by using tildes or something.
Granted, Vivid and Wily are EOL, but Vivid still appears active,
presumably on the phone. And vlan is unlikely to be needed to be SRU'd
there, but I prefer to be consistent given that I can see a potential
issue even if it is unlikely.
Now awaiting review from the SRU team.
** Changed in: vlan (Ubuntu Precise)
Status: Triaged => In Progress
** Changed in: vlan (Ubuntu Trusty)
Status: Triaged => In Progress
** Changed in: vlan (Ubuntu Xenial)
Status: Triaged => In Progress
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https://bugs.launchpad.net/bugs/1224007
Title:
mtu not always set properly on bond/vlan interface
Status in vlan package in Ubuntu:
Fix Released
Status in vlan source package in Precise:
In Progress
Status in vlan source package in Trusty:
In Progress
Status in vlan source package in Xenial:
In Progress
Status in vlan package in Debian:
New
Bug description:
* Description
When configuring a network with bonding+vlan and setting the MTU,
occasionally the MTU doesn't get set properly on the vlan interface.
In addition if one checks /var/log/upstart/networking.log whenever there is a failure the following message is printed:
SIOCSIFMTU: Numerical result out of range
I've tested the latest ifupdown package (0.7.44) and the problem still exists.
Multi/single CPU settings both exhibit the issue.
* Versions
This affects latest ifupdown and ubuntu p/q/r/s.
* Test Case
# Create a p/q/r/s server vm with two network interfaces
# This is reproducible on real hardware as well
# Install the following
sudo apt-get install vlan ifenslave-2.6 bridge-utils
sudo modprobe bonding 8021q
# Edit the interfaces file
/etc/networking/interfaces:
auto bond0
iface bond0 inet manual
bond-mode 802.3ad
bond-miimon 100
bond-lacp-rate 1
bond-slaves eth0 eth1
post-up ifconfig bond0 mtu 9000
auto eth0
iface eth0 inet manual
bond-master bond0
post-up ifconfig eth0 mtu 9000
auto eth1
iface eth1 inet manual
bond-master bond0
post-up ifconfig eth1 mtu 9000
auto bond0.123
iface bond0.123 inet static
address 192.168.122.68
netmask 255.255.255.0
gateway 192.168.122.1
post-up ifconfig bond0.123 mtu 9000
# edit rc.local (or another startup script) so we reboot until we hit the error
/etc/rc.local:
DEVS="eth0 eth1 bond0 bond0.123"
for d in $DEVS; do
mtu=$(cat /sys/class/net/$d/mtu)
if [ $mtu != 9000 ]; then
echo "FAIL"
exit 1
fi
done
reboot
exit 0
# Now reboot the machine, within 10m or so you should be at the login prompt
# if you ifconfig | grep MTU you will see some of our interfaces did not get
# the MTU properly set and the test failed.
# Essentially we want to ensure that all MTU's (except lo) were set to 9000
* Regression Potential
- The biggest regression potential would be around an unknown other corner case between MTU and VLANs which could cause that interface to fail to come up (by this fix trying to start it in a different order).
- It might also be possible that some users really don't want the raw MTU increased while the vlan should be.
* Workaround
Change the bond0.123 post-up command to:
post-up sleep 2 && ifconfig bond0.123 mtu 9000
Now when rebooting the interfaces will all be brought up with the
proper MTU.
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