devstack/doc/source/guides/neutron.rst

Using DevStack with neutron Networking

This guide will walk you through using OpenStack neutron with the ML2 plugin and the Open vSwitch mechanism driver.

Using Neutron with a Single Interface

In some instances, like on a developer laptop, there is only one network interface that is available. In this scenario, the physical interface is added to the Open vSwitch bridge, and the IP address of the laptop is migrated onto the bridge interface. That way, the physical interface can be used to transmit tenant network traffic, the OpenStack API traffic, and management traffic.

Physical Network Setup

In most cases where DevStack is being deployed with a single interface, there is a hardware router that is being used for external connectivity and DHCP. The developer machine is connected to this network and is on a shared subnet with other machines.

nwdiag {

inet [ shape = cloud ]; router; inet -- router;

network hardware_network {

address = "172.18.161.0/24" router [ address = "172.18.161.1" ]; devstack_laptop [ address = "172.18.161.6" ];

}

}

DevStack Configuration

HOST_IP=172.18.161.6
SERVICE_HOST=172.18.161.6
MYSQL_HOST=172.18.161.6
RABBIT_HOST=172.18.161.6
GLANCE_HOSTPORT=172.18.161.6:9292
ADMIN_PASSWORD=secrete
DATABASE_PASSWORD=secrete
RABBIT_PASSWORD=secrete
SERVICE_PASSWORD=secrete
SERVICE_TOKEN=secrete

## Neutron options
Q_USE_SECGROUP=True
FLOATING_RANGE="172.18.161.0/24"
FIXED_RANGE="10.0.0.0/24"
Q_FLOATING_ALLOCATION_POOL=start=172.18.161.250,end=172.18.161.254
PUBLIC_NETWORK_GATEWAY="172.18.161.1"
Q_L3_ENABLED=True
PUBLIC_INTERFACE=eth0
Q_USE_PROVIDERNET_FOR_PUBLIC=True
OVS_PHYSICAL_BRIDGE=br-ex
PUBLIC_BRIDGE=br-ex
OVS_BRIDGE_MAPPINGS=public:br-ex

Neutron Networking with Open vSwitch and Provider Networks

In some instances, it is desirable to use neutron's provider networking extension, so that networks that are configured on an external router can be utilized by neutron, and instances created via Nova can attach to the network managed by the external router.

For example, in some lab environments, a hardware router has been pre-configured by another party, and an OpenStack developer has been given a VLAN tag and IP address range, so that instances created via DevStack will use the external router for L3 connectivity, as opposed to the neutron L3 service.

Physical Network Setup

nwdiag {

inet [ shape = cloud ]; router; inet -- router;

network provider_net {

address = "203.0.113.0/24" router [ address = "203.0.113.1" ]; controller; compute1; compute2;

}

network control_plane {

router [ address = "10.0.0.1" ] address = "10.0.0.0/24" controller [ address = "10.0.0.2" ] compute1 [ address = "10.0.0.3" ] compute2 [ address = "10.0.0.4" ]

}

}

On a compute node, the first interface, eth0 is used for the OpenStack management (API, message bus, etc) as well as for ssh for an administrator to access the machine.

stack@compute:~$ ifconfig eth0
eth0      Link encap:Ethernet  HWaddr bc:16:65:20:af:fc
          inet addr:10.0.0.3

eth1 is manually configured at boot to not have an IP address. Consult your operating system documentation for the appropriate technique. For Ubuntu, the contents of /etc/network/interfaces contains:

auto eth1
iface eth1 inet manual
        up ifconfig $IFACE 0.0.0.0 up
        down ifconfig $IFACE 0.0.0.0 down

The second physical interface, eth1 is added to a bridge (in this case named br-ex), which is used to forward network traffic from guest VMs.

stack@compute:~$ sudo ovs-vsctl add-br br-ex
stack@compute:~$ sudo ovs-vsctl add-port br-ex eth1
stack@compute:~$ sudo ovs-vsctl show
9a25c837-32ab-45f6-b9f2-1dd888abcf0f
    Bridge br-ex
        Port br-ex
            Interface br-ex
                type: internal
        Port phy-br-ex
            Interface phy-br-ex
                type: patch
                options: {peer=int-br-ex}
        Port "eth1"
            Interface "eth1"

Service Configuration

Control Node

In this example, the control node will run the majority of the OpenStack API and management services (keystone, glance, nova, neutron)

Compute Nodes

In this example, the nodes that will host guest instances will run the neutron-openvswitch-agent for network connectivity, as well as the compute service nova-compute.

DevStack Configuration

The following is a snippet of the DevStack configuration on the controller node.

HOST_IP=10.0.0.2
SERVICE_HOST=10.0.0.2
MYSQL_HOST=10.0.0.2
SERVICE_HOST=10.0.0.2
MYSQL_HOST=10.0.0.2
RABBIT_HOST=10.0.0.2
GLANCE_HOSTPORT=10.0.0.2:9292
PUBLIC_INTERFACE=eth1

ADMIN_PASSWORD=secrete
MYSQL_PASSWORD=secrete
RABBIT_PASSWORD=secrete
SERVICE_PASSWORD=secrete
SERVICE_TOKEN=secrete

## Neutron options
Q_USE_SECGROUP=True
ENABLE_TENANT_VLANS=True
TENANT_VLAN_RANGE=3001:4000
PHYSICAL_NETWORK=default
OVS_PHYSICAL_BRIDGE=br-ex

Q_USE_PROVIDER_NETWORKING=True
Q_L3_ENABLED=False

# Do not use Nova-Network
disable_service n-net

# Neutron
ENABLED_SERVICES+=,q-svc,q-dhcp,q-meta,q-agt

## Neutron Networking options used to create Neutron Subnets

FIXED_RANGE="203.0.113.0/24"
PROVIDER_SUBNET_NAME="provider_net"
PROVIDER_NETWORK_TYPE="vlan"
SEGMENTATION_ID=2010

In this configuration we are defining FIXED_RANGE to be a publicly routed IPv4 subnet. In this specific instance we are using the special TEST-NET-3 subnet defined in RFC 5737, which is used for documentation. In your DevStack setup, FIXED_RANGE would be a public IP address range that you or your organization has allocated to you, so that you could access your instances from the public internet.

The following is the DevStack configuration on compute node 1.

HOST_IP=10.0.0.3
SERVICE_HOST=10.0.0.2
MYSQL_HOST=10.0.0.2
SERVICE_HOST=10.0.0.2
MYSQL_HOST=10.0.0.2
RABBIT_HOST=10.0.0.2
GLANCE_HOSTPORT=10.0.0.2:9292
ADMIN_PASSWORD=secrete
MYSQL_PASSWORD=secrete
RABBIT_PASSWORD=secrete
SERVICE_PASSWORD=secrete
SERVICE_TOKEN=secrete

# Services that a compute node runs
ENABLED_SERVICES=n-cpu,rabbit,q-agt

## Neutron options
PHYSICAL_NETWORK=default
OVS_PHYSICAL_BRIDGE=br-ex
PUBLIC_INTERFACE=eth1
Q_USE_PROVIDER_NETWORKING=True
Q_L3_ENABLED=False

Compute node 2's configuration will be exactly the same, except HOST_IP will be 10.0.0.4

When DevStack is configured to use provider networking (via Q_USE_PROVIDER_NETWORKING is True and Q_L3_ENABLED is False) -DevStack will automatically add the network interface defined in PUBLIC_INTERFACE to the OVS_PHYSICAL_BRIDGE

For example, with the above configuration, a bridge is created, named br-ex which is managed by Open vSwitch, and the second interface on the compute node, eth1 is attached to the bridge, to forward traffic sent by guest VMs.

Miscellaneous Tips

Disabling Next Generation Firewall Tools

DevStack does not properly operate with modern firewall tools. Specifically it will appear as if the guest VM can access the external network via ICMP, but UDP and TCP packets will not be delivered to the guest VM. The root cause of the issue is that both ufw (Uncomplicated Firewall) and firewalld (Fedora's firewall manager) apply firewall rules to all interfaces in the system, rather then per-device. One solution to this problem is to revert to iptables functionality.

To get a functional firewall configuration for Fedora do the following:

sudo service iptables save
sudo systemctl disable firewalld
sudo systemctl enable iptables
sudo systemctl stop firewalld
sudo systemctl start iptables

To get a functional firewall configuration for distributions containing ufw, disable ufw. Note ufw is generally not enabled by default in Ubuntu. To disable ufw if it was enabled, do the following:

sudo service iptables save
sudo ufw disable

Configuring Extension Drivers for the ML2 Plugin

Extension drivers for the ML2 plugin are set with the variable Q_ML2_PLUGIN_EXT_DRIVERS, and includes the 'port_security' extension by default. If you want to remove all the extension drivers (even 'port_security'), set Q_ML2_PLUGIN_EXT_DRIVERS to blank.