Configure neutron agents

Plug-ins typically have requirements for particular software that must be run on each node that handles data packets. This includes any node that runs nova-compute and nodes that run dedicated OpenStack Networking service agents such as neutron-dhcp-agent, neutron-l3-agent or neutron-metering-agent.

A data-forwarding node typically has a network interface with an IP address on the management network and another interface on the data network.

This section shows you how to install and configure a subset of the available plug-ins, which might include the installation of switching software (for example, Open vSwitch) and as agents used to communicate with the neutron-server process running elsewhere in the data center.

Configure data-forwarding nodes

Node set up: NSX plug-in

If you use the NSX plug-in, you must also install Open vSwitch on each data-forwarding node. However, you do not need to install an additional agent on each node.


It is critical that you run an Open vSwitch version that is compatible with the current version of the NSX Controller software. Do not use the Open vSwitch version that is installed by default on Ubuntu. Instead, use the Open vSwitch version that is provided on the VMware support portal for your NSX Controller version.

To set up each node for the NSX plug-in

  1. Ensure that each data-forwarding node has an IP address on the management network, and an IP address on the data network that is used for tunneling data traffic. For full details on configuring your forwarding node, see the NSX Administration Guide.

  2. Use the NSX Administrator Guide to add the node as a Hypervisor by using the NSX Manager GUI. Even if your forwarding node has no VMs and is only used for services agents like neutron-dhcp-agent , it should still be added to NSX as a Hypervisor.

  3. After following the NSX Administrator Guide, use the page for this Hypervisor in the NSX Manager GUI to confirm that the node is properly connected to the NSX Controller Cluster and that the NSX Controller Cluster can see the br-int integration bridge.

Configure DHCP agent

The DHCP service agent is compatible with all existing plug-ins and is required for all deployments where VMs should automatically receive IP addresses through DHCP.

To install and configure the DHCP agent

  1. You must configure the host running the neutron-dhcp-agent as a data forwarding node according to the requirements for your plug-in.

  2. Install the DHCP agent:

    # apt-get install neutron-dhcp-agent
  3. Update any options in the /etc/neutron/dhcp_agent.ini file that depend on the plug-in in use. See the sub-sections.


    If you reboot a node that runs the DHCP agent, you must run the neutron-ovs-cleanup command before the neutron-dhcp-agent service starts.

    On Red Hat, SUSE, and Ubuntu based systems, the neutron-ovs-cleanup service runs the neutron-ovs-cleanup command automatically. However, on Debian-based systems, you must manually run this command or write your own system script that runs on boot before the neutron-dhcp-agent service starts.

Networking dhcp-agent can use dnsmasq driver which supports stateful and stateless DHCPv6 for subnets created with --ipv6_address_mode set to dhcpv6-stateful or dhcpv6-stateless.

For example:

$ openstack subnet create --ip-version 6 --ipv6-ra-mode dhcpv6-stateful \
  --ipv6-address-mode dhcpv6-stateful --network NETWORK --subnet-range \
$ openstack subnet create --ip-version 6 --ipv6-ra-mode dhcpv6-stateless \
  --ipv6-address-mode dhcpv6-stateless --network NETWORK --subnet-range \

If no dnsmasq process for subnet’s network is launched, Networking will launch a new one on subnet’s dhcp port in qdhcp-XXX namespace. If previous dnsmasq process is already launched, restart dnsmasq with a new configuration.

Networking will update dnsmasq process and restart it when subnet gets updated.


For dhcp-agent to operate in IPv6 mode use at least dnsmasq v2.63.

After a certain, configured timeframe, networks uncouple from DHCP agents when the agents are no longer in use. You can configure the DHCP agent to automatically detach from a network when the agent is out of service, or no longer needed.

This feature applies to all plug-ins that support DHCP scaling. For more information, see the DHCP agent configuration options listed in the OpenStack Configuration Reference.

DHCP agent setup: OVS plug-in

These DHCP agent options are required in the /etc/neutron/dhcp_agent.ini file for the OVS plug-in:

enable_isolated_metadata = True
interface_driver = openvswitch

DHCP agent setup: NSX plug-in

These DHCP agent options are required in the /etc/neutron/dhcp_agent.ini file for the NSX plug-in:

enable_metadata_network = True
enable_isolated_metadata = True
interface_driver = openvswitch

DHCP agent setup: Linux-bridge plug-in

These DHCP agent options are required in the /etc/neutron/dhcp_agent.ini file for the Linux-bridge plug-in:

enabled_isolated_metadata = True
interface_driver = linuxbridge

Configure L3 agent

The OpenStack Networking service has a widely used API extension to allow administrators and projects to create routers to interconnect L2 networks, and floating IPs to make ports on private networks publicly accessible.

Many plug-ins rely on the L3 service agent to implement the L3 functionality. However, the following plug-ins already have built-in L3 capabilities:

  • Big Switch/Floodlight plug-in, which supports both the open source Floodlight controller and the proprietary Big Switch controller.


    Only the proprietary BigSwitch controller implements L3 functionality. When using Floodlight as your OpenFlow controller, L3 functionality is not available.

  • IBM SDN-VE plug-in

  • MidoNet plug-in

  • NSX plug-in

  • PLUMgrid plug-in


Do not configure or use neutron-l3-agent if you use one of these plug-ins.

To install the L3 agent for all other plug-ins

  1. Install the neutron-l3-agent binary on the network node:

    # apt-get install neutron-l3-agent
  2. To uplink the node that runs neutron-l3-agent to the external network, create a bridge named br-ex and attach the NIC for the external network to this bridge.

    For example, with Open vSwitch and NIC eth1 connected to the external network, run:

    # ovs-vsctl add-br br-ex
    # ovs-vsctl add-port br-ex eth1

    When the br-ex port is added to the eth1 interface, external communication is interrupted. To avoid this, edit the /etc/network/interfaces file to contain the following information:

    ## External bridge
    auto br-ex
    iface br-ex inet static
    ## External network interface
    auto eth1
    iface eth1 inet manual
    up ifconfig $IFACE up
    up ip link set $IFACE promisc on
    down ip link set $IFACE promisc off
    down ifconfig $IFACE down


    The external bridge configuration address is the external IP address. This address and gateway should be configured in /etc/network/interfaces.

    After editing the configuration, restart br-ex:

    # ifdown br-ex && ifup br-ex

    Do not manually configure an IP address on the NIC connected to the external network for the node running neutron-l3-agent. Rather, you must have a range of IP addresses from the external network that can be used by OpenStack Networking for routers that uplink to the external network. This range must be large enough to have an IP address for each router in the deployment, as well as each floating IP.

  3. The neutron-l3-agent uses the Linux IP stack and iptables to perform L3 forwarding and NAT. In order to support multiple routers with potentially overlapping IP addresses, neutron-l3-agent defaults to using Linux network namespaces to provide isolated forwarding contexts. As a result, the IP addresses of routers are not visible simply by running the ip addr list or ifconfig command on the node. Similarly, you cannot directly ping fixed IPs.

    To do either of these things, you must run the command within a particular network namespace for the router. The namespace has the name qrouter-ROUTER_UUID. These example commands run in the router namespace with UUID 47af3868-0fa8-4447-85f6-1304de32153b:

    # ip netns exec qrouter-47af3868-0fa8-4447-85f6-1304de32153b ip addr list
    # ip netns exec qrouter-47af3868-0fa8-4447-85f6-1304de32153b ping FIXED_IP


    If you reboot a node that runs the L3 agent, you must run the neutron-ovs-cleanup command before the neutron-l3-agent service starts.

    On Red Hat, SUSE and Ubuntu based systems, the neutron-ovs-cleanup service runs the neutron-ovs-cleanup command automatically. However, on Debian-based systems, you must manually run this command or write your own system script that runs on boot before the neutron-l3-agent service starts.

How routers are assigned to L3 agents By default, a router is assigned to the L3 agent with the least number of routers (LeastRoutersScheduler). This can be changed by altering the router_scheduler_driver setting in the configuration file.

Configure metering agent

The Neutron Metering agent resides beside neutron-l3-agent.

To install the metering agent and configure the node

  1. Install the agent by running:

    # apt-get install neutron-metering-agent
  2. If you use one of the following plug-ins, you need to configure the metering agent with these lines as well:

    • An OVS-based plug-in such as OVS, NSX, NEC, BigSwitch/Floodlight:

      interface_driver = openvswitch
    • A plug-in that uses LinuxBridge:

      interface_driver = linuxbridge
  3. To use the reference implementation, you must set:

    driver = iptables
  4. Set the service_plugins option in the /etc/neutron/neutron.conf file on the host that runs neutron-server:

    service_plugins = metering

    If this option is already defined, add metering to the list, using a comma as separator. For example:

    service_plugins = router,metering

Configure Hyper-V L2 agent

Before you install the OpenStack Networking Hyper-V L2 agent on a Hyper-V compute node, ensure the compute node has been configured correctly using these instructions.

To install the OpenStack Networking Hyper-V agent and configure the node

  1. Download the OpenStack Networking code from the repository:

    > cd C:\OpenStack\
    > git clone
  2. Install the OpenStack Networking Hyper-V Agent:

    > cd C:\OpenStack\neutron\
    > python install
  3. Copy the policy.yaml file:

    > xcopy C:\OpenStack\neutron\etc\policy.yaml C:\etc\
  4. Create the C:\etc\neutron-hyperv-agent.conf file and add the proper configuration options and the Hyper-V related options. Here is a sample config file:

    control_exchange = neutron
    policy_file = C:\etc\policy.yaml
    rpc_backend = neutron.openstack.common.rpc.impl_kombu
    rabbit_host = IP_ADDRESS
    rabbit_port = 5672
    rabbit_userid = guest
    rabbit_password = <password>
    logdir = C:\OpenStack\Log
    logfile = neutron-hyperv-agent.log
    polling_interval = 2
    physical_network_vswitch_mappings = *:YOUR_BRIDGE_NAME
    enable_metrics_collection = true
    firewall_driver = hyperv.neutron.security_groups_driver.HyperVSecurityGroupsDriver
    enable_security_group = true
  5. Start the OpenStack Networking Hyper-V agent:

    > C:\Python27\Scripts\neutron-hyperv-agent.exe --config-file

Basic operations on agents

This table shows examples of Networking commands that enable you to complete basic operations on agents.



List all available agents.

$ openstack network agent list

Show information of a given agent.

$ openstack network agent show AGENT_ID

Update the admin status and description for a specified agent. The command can be used to enable and disable agents by using --admin-state-up parameter set to False or True.

$ neutron agent-update --admin-state-up False AGENT_ID

Delete a given agent. Consider disabling the agent before deletion.

$ openstack network agent delete AGENT_ID

Basic operations on Networking agents

See the OpenStack Command-Line Interface Reference for more information on Networking commands.