---
issues:
  - |
    The high availability of metadata service on isolated networks is limited
    or non-existent. IPv4 metadata is redundant when the DHCP agent managing
    it is redundant, but recovery is tied to the renewal of the DHCP lease,
    making most recoveries very slow. IPv6 metadata is not redundant at all
    as the IPv6 metadata address can only be configured in a single place at
    a time as it is link-local. Multiple agents trying to configure it will
    generate an IPv6 duplicate address detection failure.

    Administrators may observe the IPv6 metadata address in "dadfailed" state
    in the DHCP namespace for this reason, which is only an indication it is
    not highly available. Until a redesign is made to the isolated metadata
    service there is not a better deployment option. See `bug 1953165
    <https://bugs.launchpad.net/neutron/+bug/1953165>`_ for information.
