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Dmitriy Rabotyagov 77eacd1028 [doc] Add LXB scenario documentation

Since LXB was installed by default, we never had it described
explicitly as all other examples were reffering to it. Now when we've
switched to OVN as default driver, we should describe path for LXB
as well as make adjustments to reflect new defaults for neutron role.

Change-Id: I98011dbbe3a3c2f6992e1a150e5ec97642398fc0

2023-01-17 14:17:41 +00:00

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Scenario - Using Linux Bridge

Overview

Operators can choose to utilize Linux Bridges instead of Open vSwitch for the neutron ML2 agent. This document outlines how to set it up in your environment.

Warning

LinuxBridge driver is considered as experimental in Neutron and is discouraged for usage as of today.

Prerequisites

All compute nodes must have bridges configured:

br-mgmt - Bridge is used to wire LXC containers. Can be regular interface for bare metal deployments
br-vlan (optional - used for vlan networks). Can be regular interface.
br-vxlan (optional - used for vxlan tenant networks). Can be regular interface.
br-storage (optional - used for certain storage devices). It's also used to wire LXC containers. Can be regular interface for bare metal nodes.

For more information see: https://docs.openstack.org/project-deploy-guide/openstack-ansible/newton/targethosts-networkconfig.html

Configuring bridges (Linux Bridge)

The following is an example of how to configure a bridge (example: br-mgmt) with a Linux Bridge on Ubuntu 16.04 LTS:

/etc/network/interfaces

auto lo
iface lo inet loopback

# Management network
auto eth0
iface eth0 inet manual

# VLAN network
auto eth1
iface eth1 inet manual

source /etc/network/interfaces.d/*.cfg

/etc/network/interfaces.d/br-mgmt.cfg

# OpenStack Management network bridge
auto br-mgmt
iface br-mgmt inet static
  bridge_stp off
  bridge_waitport 0
  bridge_fd 0
  bridge_ports eth0
  address MANAGEMENT_NETWORK_IP
  netmask 255.255.255.0

One br-<type>.cfg is required for each bridge. VLAN interfaces can be used to back the br-<type> bridges if there are limited physical adapters on the system.

OpenStack-Ansible user variables

Specify provider network definitions in your /etc/openstack_deploy/openstack_user_config.yml that define one or more Neutron provider bridges and related configuration:

- network:
    container_bridge: "br-provider"
    container_type: "veth"
    type: "vlan"
    range: "101:200,301:400"
    net_name: "physnet1"
    network_interface: "bond1"
    group_binds:
      - neutron_linuxbridge_agent
- network:
    container_bridge: "br-provider2"
    container_type: "veth"
    type: "vlan"
    range: "203:203,467:500"
    net_name: "physnet2"
    network_interface: "bond2"
    group_binds:
      - neutron_linuxbridge_agent

When using flat provider networks, modify the network type accordingly:

- network:
    container_bridge: "br-publicnet"
    container_type: "veth"
    type: "flat"
    net_name: "flat"
    group_binds:
      - neutron_linuxbridge_agent

Specify an overlay network definition in your /etc/openstack_deploy/openstack_user_config.yml that defines overlay network-related configuration:

Note

The bridge name should correspond to a pre-created Linux bridge.

- network:
    container_bridge: "br-vxlan"
    container_type: "veth"
    container_interface: "eth10"
    ip_from_q: "tunnel"
    type: "vxlan"
    range: "1:1000"
    net_name: "vxlan"
    group_binds:
      - neutron_linuxbridge_agent

Set the following user variables in your /etc/openstack_deploy/user_variables.yml:

neutron_plugin_type: ml2.lxb

neutron_ml2_drivers_type: "flat,vlan,vxlan"
neutron_plugin_base:
  - router
  - metering

The overrides are instructing Ansible to deploy the LXB mechanism driver and associated LXB components. This is done by setting neutron_plugin_type to ml2.lxb.

The neutron_ml2_drivers_type override provides support for all common type drivers supported by LXB.

The neutron_plugin_base is used to defined list of plugins that will be enabled.

If provider network overrides are needed on a global or per-host basis, the following format can be used in user_variables.yml or per-host in openstack_user_config.yml.