Comment 11 for bug 1859832

Reviewed: https://review.opendev.org/717720
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=b9a29681003b7f975d7bc9687399cafb5549010a
Submitter: Zuul
Branch: stable/stein

commit b9a29681003b7f975d7bc9687399cafb5549010a
Author: LIU Yulong <email address hidden>
Date: Thu Oct 31 19:06:37 2019 +0800

    Do not link up HA router gateway in backup node

    L3 router will set its devices link up by default.
    For HA routers, the gateway device will be pluged
    in all scheduled hosts. When the gateway deivce is
    up in backup node, it will send out IPv6 related
    packets (MLDv2) according to some kernal config.
    This will cause the physical fabric think that the
    gateway MAC is now working in the backup node. And
    finally the master node L3 traffic will be broken.

    This patch sets the backup gateway device link down
    by default. When the VRRP sets the master state in
    one host, the L3 agent state change procedure will
    do link up action for the gateway device.

    Closes-Bug: #1859832
    Change-Id: I8dca2c1a2f8cb467cfb44420f0eea54ca0932b05
    (cherry picked from commit c52029c39aa824a67095fbbf9e59eff769d92587)