The L3 API in OpenStack Networking supports multiple floating IP pools. In OpenStack Networking, a floating IP pool is represented as an external network and a floating IP is allocated from a subnet associated with the external network. Since each L3 agent can be associated with at most one external network, we need to invoke multiple L3 agent to define multiple floating IP pools. 'gateway_external_network_id' in L3 agent configuration file indicates the external network that the L3 agent handles. You can run multiple L3 agent instances on one host.
In addition, when you run multiple L3 agents, make sure that handle_internal_only_routers is set to True only for one L3 agent in an OpenStack Networking deployment and set to False for all other L3 agents. Since the default value of this parameter is True, you need to configure it carefully.
Before starting L3 agents, you need to create routers and external networks, then update the configuration files with UUID of external networks and start L3 agents.
For the first agent, invoke it with the following l3_agent.ini where handle_internal_only_routers is True.
handle_internal_only_routers = True gateway_external_network_id = 2118b11c-011e-4fa5-a6f1-2ca34d372c35 external_network_bridge = br-ex
python /opt/stack/neutron/bin/neutron-l3-agent --config-file /etc/neutron/neutron.conf --config-file=/etc/neutron/l3_agent.ini
For the second (or later) agent, invoke it with the following l3_agent.ini where handle_internal_only_routers is False.
handle_internal_only_routers = False gateway_external_network_id = e828e54c-850a-4e74-80a8-8b79c6a285d8 external_network_bridge = br-ex-2
