neutron/doc/source/admin/deploy-lb-provider.rst

Linux bridge: Provider networks

The provider networks architecture example provides layer-2 connectivity between instances and the physical network infrastructure using VLAN (802.1q) tagging. It supports one untagged (flat) network and up to 4095 tagged (VLAN) networks. The actual quantity of VLAN networks depends on the physical network infrastructure. For more information on provider networks, see intro-os-networking-provider.

Prerequisites

One controller node with the following components:

• Two network interfaces: management and provider.
• OpenStack Networking server service and ML2 plug-in.

Two compute nodes with the following components:

• Two network interfaces: management and provider.
• OpenStack Networking Linux bridge layer-2 agent, DHCP agent, metadata agent, and any dependencies.

Note

Larger deployments typically deploy the DHCP and metadata agents on a subset of compute nodes to increase performance and redundancy. However, too many agents can overwhelm the message bus. Also, to further simplify any deployment, you can omit the metadata agent and use a configuration drive to provide metadata to instances.

Architecture

The following figure shows components and connectivity for one untagged (flat) network. In this particular case, the instance resides on the same compute node as the DHCP agent for the network. If the DHCP agent resides on another compute node, the latter only contains a DHCP namespace and Linux bridge with a port on the provider physical network interface.

The following figure describes virtual connectivity among components for two tagged (VLAN) networks. Essentially, each network uses a separate bridge that contains a port on the VLAN sub-interface on the provider physical network interface. Similar to the single untagged network case, the DHCP agent may reside on a different compute node.

Note

These figures omit the controller node because it does not handle instance network traffic.

Example configuration

Use the following example configuration as a template to deploy provider networks in your environment.

Controller node

1. Install the Networking service components that provides the neutron-server service and ML2 plug-in.

2. In the neutron.conf file:

   • Configure common options:

   • Disable service plug-ins because provider networks do not require any. However, this breaks portions of the dashboard that manage the Networking service. See the latest Install Tutorials and Guides for more information.

     [DEFAULT]
     service_plugins =

   • Enable two DHCP agents per network so both compute nodes can provide DHCP service provider networks.

     [DEFAULT]
     dhcp_agents_per_network = 2

   • If necessary, configure MTU <config-mtu>.

3. In the ml2_conf.ini file:

   • Configure drivers and network types:

     [ml2]
     type_drivers = flat,vlan
     tenant_network_types =
     mechanism_drivers = linuxbridge
     extension_drivers = port_security

   • Configure network mappings:

     [ml2_type_flat]
     flat_networks = provider
     
     [ml2_type_vlan]
     network_vlan_ranges = provider

     Note

     The tenant_network_types option contains no value because the architecture does not support self-service networks.

     Note

     The provider value in the network_vlan_ranges option lacks VLAN ID ranges to support use of arbitrary VLAN IDs.

4. Populate the database.

   # su -s /bin/sh -c "neutron-db-manage --config-file /etc/neutron/neutron.conf \
     --config-file /etc/neutron/plugins/ml2/ml2_conf.ini upgrade head" neutron

5. Start the following services:

   • Server

Compute nodes

1. Install the Networking service Linux bridge layer-2 agent.

2. In the neutron.conf file, configure common options:

3. In the linuxbridge_agent.ini file, configure the Linux bridge agent:

   [linux_bridge]
   physical_interface_mappings = provider:PROVIDER_INTERFACE
   
   [vxlan]
   enable_vxlan = False
   
   [securitygroup]
   firewall_driver = iptables

   Replace PROVIDER_INTERFACE with the name of the underlying interface that handles provider networks. For example, eth1.

4. In the dhcp_agent.ini file, configure the DHCP agent:

   [DEFAULT]
   interface_driver = linuxbridge
   enable_isolated_metadata = True
   force_metadata = True

   Note

   The force_metadata option forces the DHCP agent to provide a host route to the metadata service on 169.254.169.254 regardless of whether the subnet contains an interface on a router, thus maintaining similar and predictable metadata behavior among subnets.

5. In the metadata_agent.ini file, configure the metadata agent:

   [DEFAULT]
   nova_metadata_host = controller
   metadata_proxy_shared_secret = METADATA_SECRET

   The value of METADATA_SECRET must match the value of the same option in the [neutron] section of the nova.conf file.

6. Start the following services:

   • Linux bridge agent
   • DHCP agent
   • Metadata agent

Verify service operation

1. Source the administrative project credentials.

2. Verify presence and operation of the agents:

   $ openstack network agent list
   +--------------------------------------+--------------------+----------+-------------------+-------+-------+---------------------------+
   | ID                                   | Agent Type         | Host     | Availability Zone | Alive | State | Binary                    |
   +--------------------------------------+--------------------+----------+-------------------+-------+-------+---------------------------+
   | 09de6af6-c5f1-4548-8b09-18801f068c57 | Linux bridge agent | compute2 | None              | True  | UP    | neutron-linuxbridge-agent |
   | 188945d1-9e70-4803-a276-df924e0788a4 | Linux bridge agent | compute1 | None              | True  | UP    | neutron-linuxbridge-agent |
   | e76c440d-d5f6-4316-a674-d689630b629e | DHCP agent         | compute1 | nova              | True  | UP    | neutron-dhcp-agent        |
   | e67367de-6657-11e6-86a4-931cd04404bb | DHCP agent         | compute2 | nova              | True  | UP    | neutron-dhcp-agent        |
   | e8174cae-6657-11e6-89f0-534ac6d0cb5c | Metadata agent     | compute1 | None              | True  | UP    | neutron-metadata-agent    |
   | ece49ec6-6657-11e6-bafb-c7560f19197d | Metadata agent     | compute2 | None              | True  | UP    | neutron-metadata-agent    |
   +--------------------------------------+--------------------+----------+-------------------+-------+-------+---------------------------+

Create initial networks

Verify network operation

Network traffic flow

North-south scenario: Instance with a fixed IP address

• The instance resides on compute node 1 and uses provider network 1.
• The instance sends a packet to a host on the Internet.

The following steps involve compute node 1.

1. The instance interface (1) forwards the packet to the provider bridge instance port (2) via veth pair.
2. Security group rules (3) on the provider bridge handle firewalling and connection tracking for the packet.
3. The VLAN sub-interface port (4) on the provider bridge forwards the packet to the physical network interface (5).
4. The physical network interface (5) adds VLAN tag 101 to the packet and forwards it to the physical network infrastructure switch (6).

The following steps involve the physical network infrastructure:

1. The switch removes VLAN tag 101 from the packet and forwards it to the router (7).
2. The router routes the packet from the provider network (8) to the external network (9) and forwards the packet to the switch (10).
3. The switch forwards the packet to the external network (11).
4. The external network (12) receives the packet.

Note

Return traffic follows similar steps in reverse.

East-west scenario 1: Instances on the same network

Instances on the same network communicate directly between compute nodes containing those instances.

• Instance 1 resides on compute node 1 and uses provider network 1.
• Instance 2 resides on compute node 2 and uses provider network 1.
• Instance 1 sends a packet to instance 2.

The following steps involve compute node 1:

1. The instance 1 interface (1) forwards the packet to the provider bridge instance port (2) via veth pair.
2. Security group rules (3) on the provider bridge handle firewalling and connection tracking for the packet.
3. The VLAN sub-interface port (4) on the provider bridge forwards the packet to the physical network interface (5).
4. The physical network interface (5) adds VLAN tag 101 to the packet and forwards it to the physical network infrastructure switch (6).

The following steps involve the physical network infrastructure:

1. The switch forwards the packet from compute node 1 to compute node 2 (7).

The following steps involve compute node 2:

1. The physical network interface (8) removes VLAN tag 101 from the packet and forwards it to the VLAN sub-interface port (9) on the provider bridge.
2. Security group rules (10) on the provider bridge handle firewalling and connection tracking for the packet.
3. The provider bridge instance port (11) forwards the packet to the instance 2 interface (12) via veth pair.

Note

Return traffic follows similar steps in reverse.

East-west scenario 2: Instances on different networks

Instances communicate via router on the physical network infrastructure.

• Instance 1 resides on compute node 1 and uses provider network 1.
• Instance 2 resides on compute node 1 and uses provider network 2.
• Instance 1 sends a packet to instance 2.

Note

Both instances reside on the same compute node to illustrate how VLAN tagging enables multiple logical layer-2 networks to use the same physical layer-2 network.

The following steps involve the compute node:

1. The instance 1 interface (1) forwards the packet to the provider bridge instance port (2) via veth pair.
2. Security group rules (3) on the provider bridge handle firewalling and connection tracking for the packet.
3. The VLAN sub-interface port (4) on the provider bridge forwards the packet to the physical network interface (5).
4. The physical network interface (5) adds VLAN tag 101 to the packet and forwards it to the physical network infrastructure switch (6).

The following steps involve the physical network infrastructure:

1. The switch removes VLAN tag 101 from the packet and forwards it to the router (7).
2. The router routes the packet from provider network 1 (8) to provider network 2 (9).
3. The router forwards the packet to the switch (10).
4. The switch adds VLAN tag 102 to the packet and forwards it to compute node 1 (11).

The following steps involve the compute node:

1. The physical network interface (12) removes VLAN tag 102 from the packet and forwards it to the VLAN sub-interface port (13) on the provider bridge.
2. Security group rules (14) on the provider bridge handle firewalling and connection tracking for the packet.
3. The provider bridge instance port (15) forwards the packet to the instance 2 interface (16) via veth pair.

Note

Return traffic follows similar steps in reverse.