Networking Option 2: Self-service networks¶

Install and configure the Networking components on the controller node.

Install the components¶

# yum install openstack-neutron openstack-neutron-ml2 \
  openstack-neutron-linuxbridge python-neutronclient ebtables ipset

Configure the server component¶

Edit the /etc/neutron/neutron.conf file and complete the following actions:
- In the [database] section, configure database access:
```
[database]
...
connection = mysql://neutron:NEUTRON_DBPASS@controller/neutron
```
  Replace NEUTRON_DBPASS with the password you chose for the database.
- In the [DEFAULT] section, enable the Modular Layer 2 (ML2) plug-in, router service, and overlapping IP addresses:
```
[DEFAULT]
...
core_plugin = ml2
service_plugins = router
allow_overlapping_ips = True
```
- In the [DEFAULT] and [oslo_messaging_rabbit] sections, configure RabbitMQ message queue access:
```
[DEFAULT]
...
rpc_backend = rabbit

[oslo_messaging_rabbit]
...
rabbit_host = controller
rabbit_userid = openstack
rabbit_password = RABBIT_PASS
```
  Replace RABBIT_PASS with the password you chose for the openstack account in RabbitMQ.
- In the [DEFAULT] and [keystone_authtoken] sections, configure Identity service access:
```
[DEFAULT]
...
auth_strategy = keystone

[keystone_authtoken]
...
auth_uri = http://controller:5000
auth_url = http://controller:35357
auth_plugin = password
project_domain_id = default
user_domain_id = default
project_name = service
username = neutron
password = NEUTRON_PASS
```
  Replace NEUTRON_PASS with the password you chose for the neutron user in the Identity service.
  
  Note
  
  Comment out or remove any other options in the [keystone_authtoken] section.
- In the [DEFAULT] and [nova] sections, configure Networking to notify Compute of network topology changes:
```
[DEFAULT]
...
notify_nova_on_port_status_changes = True
notify_nova_on_port_data_changes = True
nova_url = http://controller:8774/v2

[nova]
...
auth_url = http://controller:35357
auth_plugin = password
project_domain_id = default
user_domain_id = default
region_name = RegionOne
project_name = service
username = nova
password = NOVA_PASS
```
  Replace NOVA_PASS with the password you chose for the nova user in the Identity service.
- In the [oslo_concurrency] section, configure the lock path:
```
[oslo_concurrency]
...
lock_path = /var/lib/neutron/tmp
```
- (Optional) To assist with troubleshooting, enable verbose logging in the [DEFAULT] section:
```
[DEFAULT]
...
verbose = True
```

Configure the Modular Layer 2 (ML2) plug-in¶

The ML2 plug-in uses the Linux bridge mechanism to build layer-2 (bridging and switching) virtual networking infrastructure for instances.

Edit the /etc/neutron/plugins/ml2/ml2_conf.ini file and complete the following actions:
- In the [ml2] section, enable flat, VLAN, and VXLAN networks:
```
[ml2]
...
type_drivers = flat,vlan,vxlan
```
- In the [ml2] section, enable VXLAN project (private) networks:
```
[ml2]
...
tenant_network_types = vxlan
```
- In the [ml2] section, enable the Linux bridge and layer-2 population mechanisms:
```
[ml2]
...
mechanism_drivers = linuxbridge,l2population
```
  Warning
  
  After you configure the ML2 plug-in, removing values in the type_drivers option can lead to database inconsistency.
  
  Note
  
  The Linux bridge agent only supports VXLAN overlay networks.
- In the [ml2] section, enable the port security extension driver:
```
[ml2]
...
extension_drivers = port_security
```
- In the [ml2_type_flat] section, configure the public flat provider network:
```
[ml2_type_flat]
...
flat_networks = public
```
- In the [ml2_type_vxlan] section, configure the VXLAN network identifier range for private networks:
```
[ml2_type_vxlan]
...
vni_ranges = 1:1000
```
- In the [securitygroup] section, enable ipset to increase efficiency of security group rules:
```
[securitygroup]
...
enable_ipset = True
```

Configure the Linux bridge agent¶

The Linux bridge agent builds layer-2 (bridging and switching) virtual networking infrastructure for instances including VXLAN tunnels for private networks and handles security groups.

Edit the /etc/neutron/plugins/ml2/linuxbridge_agent.ini file and complete the following actions:
- In the [linux_bridge] section, map the public virtual network to the public physical network interface:
```
[linux_bridge]
physical_interface_mappings = public:PUBLIC_INTERFACE_NAME
```
  Replace PUBLIC_INTERFACE_NAME with the name of the underlying physical public network interface.
- In the [vxlan] section, enable VXLAN overlay networks, configure the IP address of the physical network interface that handles overlay networks, and enable layer-2 population:
```
[vxlan]
enable_vxlan = True
local_ip = OVERLAY_INTERFACE_IP_ADDRESS
l2_population = True
```
  Replace OVERLAY_INTERFACE_IP_ADDRESS with the IP address of the underlying physical network interface that handles overlay networks. The example architecture uses the management interface to tunnel traffic to the other nodes. Therefore, replace OVERLAY_INTERFACE_IP_ADDRESS with each node’s own management IP address.
- In the [agent] section, enable ARP spoofing protection:
```
[agent]
...
prevent_arp_spoofing = True
```
- In the [securitygroup] section, enable security groups and configure the Linux bridge iptables firewall driver:
```
[securitygroup]
...
enable_security_group = True
firewall_driver = neutron.agent.linux.iptables_firewall.IptablesFirewallDriver
```

Configure the layer-3 agent¶

The Layer-3 (L3) agent provides routing and NAT services for virtual networks.

Edit the /etc/neutron/l3_agent.ini file and complete the following actions:
- In the [DEFAULT] section, configure the Linux bridge interface driver and external network bridge:
```
[DEFAULT]
...
interface_driver = neutron.agent.linux.interface.BridgeInterfaceDriver
external_network_bridge =
```
  Note
  
  The external_network_bridge option intentionally lacks a value to enable multiple external networks on a single agent.
- (Optional) To assist with troubleshooting, enable verbose logging in the [DEFAULT] section:
```
[DEFAULT]
...
verbose = True
```

Configure the DHCP agent¶

The DHCP agent provides DHCP services for virtual networks.

Edit the /etc/neutron/dhcp_agent.ini file and complete the following actions:
- In the [DEFAULT] section, configure the Linux bridge interface driver, Dnsmasq DHCP driver, and enable isolated metadata so instances on public networks can access metadata over the network:
```
[DEFAULT]
...
interface_driver = neutron.agent.linux.interface.BridgeInterfaceDriver
dhcp_driver = neutron.agent.linux.dhcp.Dnsmasq
enable_isolated_metadata = True
```
- (Optional) To assist with troubleshooting, enable verbose logging in the [DEFAULT] section:
```
[DEFAULT]
...
verbose = True
```
Overlay networks such as VXLAN include additional packet headers that increase overhead and decrease space available for the payload or user data. Without knowledge of the virtual network infrastructure, instances attempt to send packets using the default Ethernet maximum transmission unit (MTU) of 1500 bytes. Internet protocol (IP) networks contain the path MTU discovery (PMTUD) mechanism to detect end-to-end MTU and adjust packet size accordingly. However, some operating systems and networks block or otherwise lack support for PMTUD causing performance degradation or connectivity failure.

Ideally, you can prevent these problems by enabling jumbo frames on the physical network that contains your tenant virtual networks. Jumbo frames support MTUs up to approximately 9000 bytes which negates the impact of VXLAN overhead on virtual networks. However, many network devices lack support for jumbo frames and OpenStack administrators often lack control over network infrastructure. Given the latter complications, you can also prevent MTU problems by reducing the instance MTU to account for VXLAN overhead. Determining the proper MTU value often takes experimentation, but 1450 bytes works in most environments. You can configure the DHCP server that assigns IP addresses to your instances to also adjust the MTU.

Note

Some cloud images ignore the DHCP MTU option in which case you should configure it using metadata, a script, or other suitable method.
- In the [DEFAULT] section, enable the dnsmasq configuration file:
```
[DEFAULT]
...
dnsmasq_config_file = /etc/neutron/dnsmasq-neutron.conf
```
- Create and edit the /etc/neutron/dnsmasq-neutron.conf file to enable the DHCP MTU option (26) and configure it to 1450 bytes:
```
dhcp-option-force=26,1450
```

Return to Networking controller node configuration.