Note: This project currently supports both the Grizzly and Havana releases of OpenStack, though we will refer to Havana's Neutron for the purposes of this doc.
Currently, OpenStack does not have built-in support for highly available virtual routers or DHCP services. In the existing releases, virtual routers and DHCP services are scheduled to a single Neutron network node, and are not rescheduled on network node failure.
Since virtual router and DHCP services are normally scheduled approximately evenly, the failure of a single Neutron network node could cause IP addressing and routing failure on a number of networks proportional to the number of Neutron network nodes in use. Because this is generally an unacceptable risk in production environments, most production deployments of OpenStack have traditionally used either the "old-style" nova network driver in HA mode instead of Neutron, or chosen to use Neutron with provider networks so as to externalize these services for high