[[ha-aa-network]]
=== OpenStack Network Nodes

OpenStack Network Nodes contains:

* Neutron DHCP Agent
* Neutron L2 Agent
* Neutron L3 Agent
* Neutron Metadata Agent
* Neutron LBaaS Agent

NOTE: The Neutron L2 Agent does not need to be highly available. It has to be
installed on each Data Forwarding Node and controls the virtual networking
drivers as Open-vSwitch or Linux Bridge. One L2 agent runs per node
and controls its virtual interfaces. That's why it cannot be distributed and
highly available.


==== Running Neutron DHCP Agent

Since the Grizzly release, OpenStack Networking service has a scheduler which
allows to run multiple agents accross nodes. Also, the DHCP agent can be natively
highly available. Please follow the http://docs.openstack.org/trunk/openstack-network/admin/content/app_demo_multi_dhcp_agents.html[OpenStack Networking guide] for
further details.

==== Running Neutron L3 Agent

Since the Grizzly release, the Neutron L3 Agent is scalable thanks to the scheduler
which allows to distribute virtual routers accross multiple nodes.
But there is no native feature to bring these routers highly available.
At this time, there exists the Active / Passive solution to run the Neutron L3
agent in failover mode with Pacemaker. Please refer to the Active / Passive
section of this guide.

==== Running Neutron Metadata Agent

There is no native feature to make this service highly available.
At this time, it exists the Active / Passive solution to run the Neutron
Metadata agent in failover mode with Pacemaker. Please refer to the Active /
Passive section of this guide.