networkd does not accept / set advertised mtu

Bug #1717471 reported by Dimitri John Ledkov on 2017-09-15
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
nplan (Ubuntu)
Critical
Dimitri John Ledkov
Xenial
Undecided
Unassigned
Zesty
Undecided
Unassigned
systemd (Ubuntu)
Undecided
Unassigned
Xenial
Undecided
Unassigned

Bug Description

[Impact]
Hosts may require a specific MTU to be set as passed by DHCP options. We should honor these settings to ensure proper communication of the host with the rest of the network.

[Test case]
1) Run netplan on a system that should receive MTU settings from DHCP.
2) Validate that the MTU configuration provided by DHCP is applied to the right interface.

[Regression Potential]
If DHCP settings specify an invalid MTU setting which is currently being ignored and letting the systems communicate correctly with the network, then these systems would regress.

---

<wgrant> Right, so as far as I can tell the neutron-api on lcy01 is configured to advertise an instance interface MTU of 1400, though that's lower than it has to be, and the new DHCP setup with networkd just doesn't respect that DHCP option.

Dimitri John Ledkov (xnox) wrote :

<wgrant> netplan needs to set DHCP.UseMTU=yes
<wgrant> If I do that, my local instance no longer behaves strangely, and the MTU is correctly 1458

Dimitri John Ledkov (xnox) wrote :

xnox> wgrant, t0mb0, veebers - i think i will just change ubuntu compiled in default for systemd-networkd to be honest.
<wgrant> xnox: That sounds perilous.
<xnox> wgrant, had to google that word.
<xnox> wgrant, alternatives is to bake that into nplan, or bake that into the cloud-image alone
<wgrant> xnox: nplan makes the most sense, IMO, rather than changing a confusing non-configurable upstream default silently in a distro patch.
<xnox> wgrant, i did that to accept search domains in resolved =/ because there is no easy way to set defaults for that, as it needs to go into the network file, and systemd only considers the first matching network file and ignores the rest (or some such)
<wgrant> Er yeah, I meant .network in the ticket when I said .link. The .link is fine.
<wgrant> systemd is so lovely.

Changed in nplan (Ubuntu):
status: New → Fix Committed
importance: Undecided → Critical
assignee: nobody → Dimitri John Ledkov (xnox)
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package nplan - 0.27

---------------
nplan (0.27) artful; urgency=medium

  [ Mathieu Trudel-Lapierre ]
  * Fix crash in systemd generator if called by an user on the command-line
  * coverage: fix exclusions to properly not cover our "never reached defaults"

  [ Dimitri John Ledkov ]
  * tests/integration.py: In teardown, stop systemd-networkd.socket.
  * src/networkd.c: Set UseMTU=true by default, whenever DHCP is in use.
    (LP: #1717471)
  * tests/integration.py: fix resolved detection.

 -- Dimitri John Ledkov <email address hidden> Fri, 15 Sep 2017 14:25:22 +0100

Changed in nplan (Ubuntu):
status: Fix Committed → Fix Released
Changed in systemd (Ubuntu):
status: New → Fix Committed
description: updated

Hello Dimitri, or anyone else affected,

Accepted nplan into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.29~17.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Changed in nplan (Ubuntu Zesty):
status: New → Fix Committed
tags: added: verification-needed verification-needed-zesty
Brian Murray (brian-murray) wrote :

Hello Dimitri, or anyone else affected,

Accepted nplan into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.29~16.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Changed in nplan (Ubuntu Xenial):
status: New → Fix Committed
tags: added: verification-needed-xenial
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package systemd - 234-2ubuntu12

---------------
systemd (234-2ubuntu12) artful; urgency=medium

  [ Dimitri John Ledkov ]
  * debian/rules: do not strip test-copy.
    This insures test-copy is large enough for test-copy tests to pass.
    (LP: #1721203)

  [ Michael Biebl ]
  * Drop systemd-timesyncd.service.d/disable-with-time-daemon.conf.
    All major NTP implementations ship a native service file nowadays with a
    Conflicts=systemd-timesyncd.service so this drop-in is no longer
    necessary. (Closes: #873185) (LP: #1721204)

 -- Dimitri John Ledkov <email address hidden> Wed, 04 Oct 2017 13:28:34 +0100

Changed in systemd (Ubuntu):
status: Fix Committed → Fix Released

Verification-done for xenial with nplan 0.29~16.04.1:

This was a regression in the development release that transpired in a new SRU that has not been migrated to the stable release. The bad version is 0.26; current state of nplan in xenial is 0.23~16.04.1 in -updates.

Verified that lxc list shows an IPv4 and IPv6 address when a container is set up to use netplan with 0.29~16.04.1.

tags: added: verification-done-xenial
removed: verification-needed-xenial
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