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Taikun OCP Guide

Table of Contents

Open vSwitch: Provider networks

This 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.

Warning

Linux distributions often package older releases of Open vSwitch that
can introduce issues during operation with the Networking service. We
recommend using at least the latest long-term stable (LTS) release of
Open vSwitch for the best experience and support from Open vSwitch. See
http://www.openvswitch.org for
available releases and the installation
instructions
for more details.

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 Open vSwitch (OVS) layer-2 agent, DHCP agent,
    metadata agent, and any dependencies including OVS.

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

Provider networks using OVS - overview

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 with a port on the OVS integration bridge.

Provider networks using OVS - components and connectivity - one network

The following figure describes virtual connectivity among components
for two tagged (VLAN) networks. Essentially, all networks use a single
OVS integration bridge with different internal VLAN tags. The internal
VLAN tags almost always differ from the network VLAN assignment in the
Networking service. Similar to the untagged network case, the DHCP agent
may reside on a different compute node.

Provider networks using OVS - components and connectivity - multiple networks

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 provide 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 = openvswitch
      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 OVS layer-2 agent, DHCP agent, and
    metadata agent.

  2. Install OVS.

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

  4. In the openvswitch_agent.ini file, configure the OVS
    agent:

    [ovs]
    bridge_mappings = provider:br-provider
    
    [securitygroup]
    firewall_driver = iptables_hybrid
  5. In the dhcp_agent.ini file, configure the DHCP
    agent:

    [DEFAULT]
    interface_driver = openvswitch
    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.

  6. 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.

  7. Start the following services:

    • OVS
  8. Create the OVS provider bridge br-provider:

    $ ovs-vsctl add-br br-provider
  9. Add the provider network interface as a port on the OVS provider
    bridge br-provider:

    $ ovs-vsctl add-port br-provider PROVIDER_INTERFACE

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

  10. Start the following services:

    • OVS 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                    |
    +--------------------------------------+--------------------+----------+-------------------+-------+-------+---------------------------+
    | 1236bbcb-e0ba-48a9-80fc-81202ca4fa51 | Metadata agent     | compute2 | None              | True  | UP    | neutron-metadata-agent    |
    | 457d6898-b373-4bb3-b41f-59345dcfb5c5 | Open vSwitch agent | compute2 | None              | True  | UP    | neutron-openvswitch-agent |
    | 71f15e84-bc47-4c2a-b9fb-317840b2d753 | DHCP agent         | compute2 | nova              | True  | UP    | neutron-dhcp-agent        |
    | a6c69690-e7f7-4e56-9831-1282753e5007 | Metadata agent     | compute1 | None              | True  | UP    | neutron-metadata-agent    |
    | af11f22f-a9f4-404f-9fd8-cd7ad55c0f68 | DHCP agent         | compute1 | nova              | True  | UP    | neutron-dhcp-agent        |
    | bcfc977b-ec0e-4ba9-be62-9489b4b0e6f1 | Open vSwitch agent | compute1 | None              | True  | UP    | neutron-openvswitch-agent |
    +--------------------------------------+--------------------+----------+-------------------+-------+-------+---------------------------+

Create initial networks

Verify network operation

Network traffic flow

North-south

  • 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 security group
    bridge instance port (2) via veth pair.
  2. Security group rules (3) on the security group bridge handle
    firewalling and connection tracking for the packet.
  3. The security group bridge OVS port (4) forwards the packet to the
    OVS integration bridge security group port (5) via veth
    pair.
  4. The OVS integration bridge adds an internal VLAN tag to the
    packet.
  5. The OVS integration bridge int-br-provider patch port
    (6) forwards the packet to the OVS provider bridge
    phy-br-provider patch port (7).
  6. The OVS provider bridge swaps the internal VLAN tag with actual VLAN
    tag 101.
  7. The OVS provider bridge provider network port (8) forwards the
    packet to the physical network interface (9).
  8. The physical network interface forwards the packet to the physical
    network infrastructure switch (10).

The following steps involve the physical network infrastructure:

  1. The switch removes VLAN tag 101 from the packet and forwards it to
    the router (11).
  2. The router routes the packet from the provider network (12) to the
    external network (13) and forwards the packet to the switch (14).
  3. The switch forwards the packet to the external network (15).
  4. The external network (16) receives the packet.

Provider networks using Open vSwitch - network traffic flow - north/south

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 security
    group bridge instance port (2) via veth pair.
  2. Security group rules (3) on the security group bridge handle
    firewalling and connection tracking for the packet.
  3. The security group bridge OVS port (4) forwards the packet to the
    OVS integration bridge security group port (5) via veth
    pair.
  4. The OVS integration bridge adds an internal VLAN tag to the
    packet.
  5. The OVS integration bridge int-br-provider patch port
    (6) forwards the packet to the OVS provider bridge
    phy-br-provider patch port (7).
  6. The OVS provider bridge swaps the internal VLAN tag with actual VLAN
    tag 101.
  7. The OVS provider bridge provider network port (8) forwards the
    packet to the physical network interface (9).
  8. The physical network interface forwards the packet to the physical
    network infrastructure switch (10).

The following steps involve the physical network infrastructure:

  1. The switch forwards the packet from compute node 1 to compute node 2
    (11).

The following steps involve compute node 2:

  1. The physical network interface (12) forwards the packet to the OVS
    provider bridge provider network port (13).
  2. The OVS provider bridge phy-br-provider patch port (14)
    forwards the packet to the OVS integration bridge
    int-br-provider patch port (15).
  3. The OVS integration bridge swaps the actual VLAN tag 101 with the
    internal VLAN tag.
  4. The OVS integration bridge security group port (16) forwards the
    packet to the security group bridge OVS port (17).
  5. Security group rules (18) on the security group bridge handle
    firewalling and connection tracking for the packet.
  6. The security group bridge instance port (19) forwards the packet to
    the instance 2 interface (20) via veth pair.

Provider networks using Open vSwitch - network traffic flow - east/west scenario 1

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 security
    group bridge instance port (2) via veth pair.
  2. Security group rules (3) on the security group bridge handle
    firewalling and connection tracking for the packet.
  3. The security group bridge OVS port (4) forwards the packet to the
    OVS integration bridge security group port (5) via veth
    pair.
  4. The OVS integration bridge adds an internal VLAN tag to the
    packet.
  5. The OVS integration bridge int-br-provider patch port
    (6) forwards the packet to the OVS provider bridge
    phy-br-provider patch port (7).
  6. The OVS provider bridge swaps the internal VLAN tag with actual VLAN
    tag 101.
  7. The OVS provider bridge provider network port (8) forwards the
    packet to the physical network interface (9).
  8. The physical network interface forwards the packet to the physical
    network infrastructure switch (10).

The following steps involve the physical network infrastructure:

  1. The switch removes VLAN tag 101 from the packet and forwards it to
    the router (11).
  2. The router routes the packet from provider network 1 (12) to
    provider network 2 (13).
  3. The router forwards the packet to the switch (14).
  4. The switch adds VLAN tag 102 to the packet and forwards it to
    compute node 1 (15).

The following steps involve the compute node:

  1. The physical network interface (16) forwards the packet to the OVS
    provider bridge provider network port (17).
  2. The OVS provider bridge phy-br-provider patch port (18)
    forwards the packet to the OVS integration bridge
    int-br-provider patch port (19).
  3. The OVS integration bridge swaps the actual VLAN tag 102 with the
    internal VLAN tag.
  4. The OVS integration bridge security group port (20) removes the
    internal VLAN tag and forwards the packet to the security group bridge
    OVS port (21).
  5. Security group rules (22) on the security group bridge handle
    firewalling and connection tracking for the packet.
  6. The security group bridge instance port (23) forwards the packet to
    the instance 2 interface (24) via veth pair.

Provider networks using Open vSwitch - network traffic flow - east/west scenario 2

Note

Return traffic follows similar steps in reverse.

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