Standalone role needs to set br-ctlplane MTU

[Alan Bishop]

The network configuration for standalone nodes supports setting the MTU on the br-ex bridge interface, but not on the br-ctplane. This causes problems when multiple standalone nodes need to communicate over the control plane, as is the case when deploying multiple nodes in a split-stack configuration.

Here is an example of the issue (taken from a CI job).

Kernel Interface table
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
br-ctlplane 1500 0 0 0 0 14 0 0 0 BMRU
br-ex 1350 40239 0 0 0 47767 0 0 0 BMRU
docker0 1500 0 0 0 0 0 0 0 0 BMU
eth0 1500 411674 0 0 0 261392 0 0 0 BMRU
genev_sys_6081 65000 0 0 0 0 0 5 0 0 BMRU
lo 65536 1096463 0 0 0 1096463 0 0 0 LRU
vxlan_sys_4789 65000 41968 0 0 0 47762 0 0 0 BMRU

[Alex Schultz (alex-schultz)]

Maybe we just need to set ControlPlaneMtu ?

[Alan Bishop (alan-bishop)]

I tried that but it didn't work, and there's a comment in net-config-standalone.j2.yaml that states the parameter is "here for compatability, not used." The patch [1] I submitted to fix this follows the advice I received from hjensas on irc.

[1] https://review.openstack.org/650117

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/650117
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=00b56e07bf8e9f36faa424c067058584b40e3904
Submitter: Zuul
Branch: master

commit 00b56e07bf8e9f36faa424c067058584b40e3904
Author: Alan Bishop <email address hidden>
Date: Thu Apr 4 15:17:31 2019 -0400

    Set Standalone's br-ctlplane MTU

    Set the br-ctlplane MTU to the InterfaceLocalMtu value. This is
    required when multiple Standalone nodes are used in a split-stack
    deployment.

    Closes-Bug: #1823993
    Change-Id: I84a35d529ee67e939db1cdadd103f88295e41e8f

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/rocky
Review: https://review.openstack.org/652813

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/652813
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=cdfd0041268f4fcfe0dcd88f20fa2e4d15fe15b9
Submitter: Zuul
Branch: stable/rocky

commit cdfd0041268f4fcfe0dcd88f20fa2e4d15fe15b9
Author: Alan Bishop <email address hidden>
Date: Thu Apr 4 15:17:31 2019 -0400

    Set Standalone's br-ctlplane MTU

    Set the br-ctlplane MTU to the InterfaceLocalMtu value. This is
    required when multiple Standalone nodes are used in a split-stack
    deployment.

    Closes-Bug: #1823993
    Change-Id: I84a35d529ee67e939db1cdadd103f88295e41e8f
    (cherry picked from commit 00b56e07bf8e9f36faa424c067058584b40e3904)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/tripleo-heat-templates 10.5.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/tripleo-heat-templates 9.4.0 release.