Comment 2 for bug 1513887

All changes that allow to configure multiple external networks on MOS were merged as a part of this blueprint https://blueprints.launchpad.net/fuel/+spec/dyn-gen-physnet-set. The following steps are required now to create an additional external network:

- create all required bridges and set up interfaces (depends on network configuration)
- add appropriate bridge mappings to [ovs] section of /etc/neutron/plugin.ini on nodes with Neutron L2 agent, e.x:
  bridge_mappings=physnet1:br-floating,physnet2:br-new, where br-new - the additional external ovs bridge
- create new external network, e.x:
  neutron net-create --provider:network_type=flat --provider:physical_network=physnet2 --router:external new_floating_net
  neutron subnet-create --name=new_floating_net__subnet --gateway-ip=192.168.122.1 --disable-dhcp --allocation-pool=start=192.168.122.50,end=192.168.122.60 new_floating_net 192.168.122.0/24

Required configuration also can be performed in astute.yaml before cluster deployment.
The default external network is also created with 'flat' type, so it will work correctly after adding additional external networks.

I checked this on the ISO #241