[RFE] NIC Config Templates Should Include MTU Settings

[Harald Jensås]

The network interface templates for network isolation accept MTU settings for every interface, but it isn't clear how to set the MTU by looking at the sample files. They should include sample MTU (set to the default of 1500).

This is really just a matter of including the defaults rather than not setting them. It will be more clear how to change the settings if we list the default MTU along with a comment explaining how to change it. I will patch the sample NIC config templates to include this setting and some comments.

Neutron has support[1] to set the guaranteed MTU for networks and network segments so that this is exposed to plug-ins. In interest of supporting the use of plug-ins to configure network devices in the future the MTU property should be set on neutron networks and segments.

We already configure the MTU on the ctlplane neutron networks, we should also do this for the isolated networks.

[1] https://developer.openstack.org/api-ref/network/v2/index.html#mtu-extensions

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/599593

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/599593
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=e644e3dda9b2cfc5a521c68ec4f4dba6fbf29abb
Submitter: Zuul
Branch: master

commit e644e3dda9b2cfc5a521c68ec4f4dba6fbf29abb
Author: Harald Jensås <email address hidden>
Date: Tue Sep 4 01:08:28 2018 +0200

    Add MTU to neutron networks and nic-config templates

    Neutron has support[1] to set the guaranteed MTU for
    networks and network segments so that this is exposed
    to plug-ins. In interest of supporting the use of
    plug-ins to configure network devices in the future
    this change adds MTU property on neutron networks.

    The new (optional) property 'mtu' in the network
    defenitions in 'network_data.yaml' is used to control
    the MTU settings. By default the mtu is '1500'.

    We already configure the MTU on the ctlplane neutron
    networks, this adds the MTU to composable networks.

    Also update the nic-config sample templates to include
    mtu settings. A heat value resource is added to
    nic-config templates to get the required minimum
    viable MTU value for bridges, bonds and member
    interfaces to ensure the MTU is large enough to allow
    the largest configured MTU to traverse the path.

    Closes-Bug: #1790537
    Change-Id: I11e38f82eb9040f77412fe8ad200fcc48031e2f8

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/tripleo-heat-templates 10.3.0 release.