--- issues: - In kernels < 3.19 ``net.ipv4.ip_nonlocal_bind`` sysctl option was not isolated to network namespace scope. L3 HA sets this option to zero to avoid sending gratuitous ARPs for IP addresses that were removed while processing. If this happens, then gratuitous ARPs will be sent. It may populate ARP cache tables of peer machines with wrong MAC addresses. fixes: - Versions of ``keepalived`` < 1.2.20 don't send gratuitous ARPs when keepalived process receives a ``SIGHUP`` signal. These versions are not packaged in some Linux distributions like Red Hat Enterprise Linux 7, CentOS 7, or Ubuntu Xenial. Not sending gratuitous ARPs may lead to peer ARP cache tables containing wrong entries about floating IP addresses until those entries are invalidated. To fix that scenario, Neutron now sends gratuitous ARPs for all new IP addresses that appear on non-HA interfaces in router namespaces. This behavior simulates behavior of new versions of ``keepalived``.