With the release of 4.2.0 of keystonemiddleware using the
in-process token cache is no longer recommended. It is recommended
that a memcache backend to store tokens is used instead,
This installs and configures memcache and configures neutron-server
to use memcache for token caching.
http://docs.openstack.org/releasenotes/keystonemiddleware/mitaka.html#id2
Change-Id: Ic921a7efbd860cbcd4da2313126f73d7bdfdb4ed