Cloned for documentation impact, refer to Bug # 967369 for implementation details.
Currently I have no idea. Please check parent bug for details. Currently packstack is disabling NetworkManager with "service NetworkManager stop" and setting NM_MANAGED=no to all network interface init scripts. But this does not work in all cases unfortunately.
According to the parent bug BZ967369 NetworkManager should still be disabled, but if running RHEL 7, it might no longer need to be disabled. Hence setting this bug to 5.0 to revisit after 5.0 released.
Parent bug has been closed - notabug. Disabling Network Manager is recommended for RHEL 6. There was no finality re RHEL 7 in parent bug before it was closed, so as far as packstack is concerned, safer to leave disabling Network Manager in for RHEL 7 too. Closing this bug as currentrelease - if this issue comes up again a new bug can be raised.