Availability zone support for Neutron was first introduced in the Mitaka release of OpenStack Networking, and supports both the DHCP and L3 agents included with Neutron. Other drivers may be supported but are outside the scope of this book.

In the environment built throughout this book, the Neutron L3 agent has been installed on most of the nodes to demonstrate standalone, highly available, and distributed virtual routers. A quick look at the Neutron agent list shows they all share a common availability zone based on default agent configuration options:

To modify the availability zone for a particular L3 agent, edit the respective agent configuration file at /etc/neutron/l3_agent.ini and modify the availability_zone configuration option as shown here:

[agent]
...
# Availability zone of this node (string value)
# availability_zone = nova
availability_zone = AZ1 

Restart the L3 agent with the following command:

# systemctl restart neutron-l3-agent 

A fresh look at the agent list reflects the change:

DHCP agents can also be associated with availability zones in a similar manner. To modify the availability zone for a particular DHCP agent, edit the respective agent configuration file at /etc/neutron/dhcp_agent.ini and modify the availability_zone configuration option as shown here:

[agent]
...
# Availability zone of this node (string value)
# availability_zone = nova
availability_zone = AZ1 

Restart the DHCP agent with the following command:

# systemctl restart neutron-dhcp-agent