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Taikun OCP Guide

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Linux bridge: High availability using VRRP


This high-availability mechanism is not compatible with the layer-2
population mechanism. You must disable layer-2 population in the
linuxbridge_agent.ini file and restart the Linux bridge
agent on all existing network and compute nodes prior to deploying the
example configuration.


Add one network node with the following components:

  • Three network interfaces: management, provider, and overlay.
  • OpenStack Networking layer-2 agent, layer-3 agent, and any


You can keep the DHCP and metadata agents on each compute node or
move them to the network nodes.


High-availability using Linux bridge with VRRP - overview

The following figure shows components and connectivity for one
self-service network and one untagged (flat) network. The master router
resides on network node 1. 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 overlay physical network

High-availability using Linux bridge with VRRP - components and connectivity - one network

Example configuration

Use the following example configuration as a template to add support
for high-availability using VRRP to an existing operational environment
that supports self-service networks.

Controller node

  1. In the neutron.conf file:
    • Enable VRRP.

      l3_ha = True
  2. Restart the following services:
    • Server

Network node 1

No changes.

Network node 2

  1. Install the Networking service Linux bridge layer-2 agent and
    layer-3 agent.

  2. In the neutron.conf file, configure common

  3. In the linuxbridge_agent.ini file, configure the
    layer-2 agent.

    physical_interface_mappings = provider:PROVIDER_INTERFACE
    enable_vxlan = True
    firewall_driver = iptables


    By default, Linux uses UDP port 8472 for VXLAN tunnel
    traffic. This default value doesn’t follow the IANA standard, which
    assigned UDP port 4789 for VXLAN communication. As a
    consequence, if this node is part of a mixed deployment, where nodes
    with both OVS and Linux bridge must communicate over VXLAN tunnels, it
    is recommended that a line containing udp_dstport = 4789 be
    added to the [vxlan] section of all the Linux bridge agents. OVS follows
    the IANA standard.

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

    Replace OVERLAY_INTERFACE_IP_ADDRESS with the IP address
    of the interface that handles VXLAN overlays for self-service

  4. In the l3_agent.ini file, configure the layer-3

    interface_driver = linuxbridge
  5. Start the following services:

    • Linux bridge agent
    • Layer-3 agent

Compute nodes

No changes.

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    |
    | 598f6357-4331-4da5-a420-0f5be000bec9 | L3 agent           | network1 | nova              | True  | UP    | neutron-l3-agent          |
    | f4734e0f-bcd5-4922-a19d-e31d56b0a7ae | Linux bridge agent | network1 | None              | True  | UP    | neutron-linuxbridge-agent |
    | 670e5805-340b-4182-9825-fa8319c99f23 | Linux bridge agent | network2 | None              | True  | UP    | neutron-linuxbridge-agent |
    | 96224e89-7c15-42e9-89c4-8caac7abdd54 | L3 agent           | network2 | nova              | True  | UP    | neutron-l3-agent          |

Create initial networks

Verify network operation

Verify failover operation

Keepalived VRRP health check

Network traffic flow

This high-availability mechanism simply augments deploy-lb-selfservice with
failover of layer-3 services to another router if the master router
fails. Thus, you can reference Self-service network traffic flow
for normal