Chapter 9. Distributed Virtual Routers

Prior to the introduction of Neutron in the Folsom release of OpenStack, all network management was built into the Nova API and was known as nova-network. Nova-network remains an alternative to Neutron, although the networking models and functionality provided by it are limited when compared to the advanced features offered by Neutron. Despite its advanced feature set, up until the Juno release, Neutron was unable to replicate one of the most common networking scenarios available with nova-network: FlatDHCP with multi-host.

The multi-host functionality of nova-network offers high availability of networking by limiting the single points of failure to individual compute nodes rather than single network nodes or L2/L3 agents. High availability using distributed virtual routers borrows many concepts from the nova-network multi-host model while retaining support for many of the networking features provided by Neutron.