Neutron uses default settings to determine the type of routers that users are allowed to create as well as the number of routers that should be deployed across L3 agents.

The following default settings are specified within the neutron.conf configuration file and only need to be modified on the host running the Neutron API service. In this environment, the neutron-server service runs on the controller01 node. The default values can be seen here:

# System-wide flag to determine the type of router
# that tenants can create.
# Only admin can override. (boolean value)
#
# router_distributed = false 

To set distributed routers as the default router type for projects, set the router_distributed  configuration option to true. For this demonstration, the default value of false is sufficient.

Once the changes have been made, restart the neutron-server service on controller01 for the changes to take effect:

# systemctl restart neutron-server