Comment 8 for bug 1933517

Reviewed: https://review.opendev.org/c/openstack/os-vif/+/798055
Committed: https://opendev.org/openstack/os-vif/commit/b837c1a74f37191692a820711e431a75516a4abf
Submitter: "Zuul (22348)"
Branch: master

commit b837c1a74f37191692a820711e431a75516a4abf
Author: Sean Mooney <email address hidden>
Date: Fri Jun 25 07:50:26 2021 +0000

    add configurable per port bridges

    This patch add a new configuration option to use
    per port bridge when hybrid_plug is false.
    This can be used with OVN to reduce packet loss
    during a live migration.

    OVN can only install openflow rules when a port both has
    external_ids set and an ofport-id assigned.
    Since the ofport-id is only assigned when a netdev matching
    the port name exists connected to the dataplane, OVN cannot
    install the flows until libvirt create the tap on the destination
    host during a live migration.

    On loaded systems this can result in multiple seconds of packet loss.
    To address this we introduce per port bridges which are connencted
    to the integration brige by a patch port pair. Since the patch port
    will exist on the dataplane during pre live migration OVN can install
    the flows on the integration bridge before we begin the migration reducing
    or avoiding packet loss.

    Change-Id: I0d55ccbef5b585330b5512e67e442b80304a2e73
    Depends-On: https://review.opendev.org/c/openstack/nova/+/797428
    Closes-Bug: #1933517