Comment 11 for bug 1767422

Reviewed: https://review.openstack.org/566865
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=adb0ac4e5454391d68026cbeee93169578a10743
Submitter: Zuul
Branch: stable/pike

commit adb0ac4e5454391d68026cbeee93169578a10743
Author: Miguel Angel Ajo <email address hidden>
Date: Fri Apr 27 18:05:48 2018 +0200

    Avoid agents adding ports as trunk by default.

    Agent OVS interface code adds ports without a vlan tag,
    if neutron-openvswitch-agent fails to set the tag, or takes
    too long, the port will be a trunk port, receiving
    traffic from the external network or any other port
    sending traffic on br-int.

    Also, those kinds of ports are triggering a code path
    on the ovs-vswitchd revalidator thread which can eventually
    hog the CPU of the host (that's a bug under investigation [1])

    [1] https://bugzilla.redhat.com/show_bug.cgi?id=1558336

    Conflicts:
        neutron/tests/functional/agent/test_ovs_lib.py

        needed the addition of the following import:
    from neutron.plugins.ml2.drivers.openvswitch.agent.common import (
        constants as agent_const)

    Co-Authored-By: Slawek Kaplonski <email address hidden>
    Change-Id: I024bbbdf7059835b2f23c264b48478c71633a43c
    Closes-Bug: 1767422
    (cherry picked from commit 88f5e11d8bf820b0124be0f6ec3c2d96011592d9)
    (cherry picked from commit 2b1d413ee90dfe2e9ae41c35ab37253df53fc6cd)