Following the install guide for OpenStack on Juno, and when running:

 neutron net-create ext-net --router:external True --provider:physical_network external --provider:network_type flat

I get:

Invalid input for operation: network_type value 'flat' not supported. (HTTP 400) (Request-ID: req-2dd98c98-bffa-43b3-849b-788cbf470643)

I have checked my ml2_conf.ini file on the networking node and it includes the line:

type_drivers = flat,gre

My ml2.conf.ini file on my Controller node has the line:

type_drivers = local,gre,flat

Don't know where else to look. Can anyone advise as to where else I need to specify 'flat' to allow this command to work?