FAQ¶

Q: Does OVN support DVR or distributed L3 routing?

DVR (Distributed Virtual Router) is typically used to refer to a specific implementation of distributed routers provided by the Neutron L3 agent. The Neutron L3 agent in DVR mode has never been tested with OVN. Support for the Neutron L3 agent is only temporary and will be removed once OVN’s native L3 support includes enough functionality.

When using OVN’s native L3 support, L3 routing is always distributed.

Q: Does OVN support integration with physical switches?

OVN currently integrates with physical switches by optionally using them as VTEP gateways from logical to physical networks and via integrations provided by the Neutron ML2 framework, hierarchical port binding.

Q: What’s the status of HA for networking-ovn and OVN?

Typically, multiple copies of neutron-server are run across multiple servers and uses a load balancer. The neutron ML2 mechanism driver provided by networking-ovn supports this deployment model. In addition, multiple copies of neutron-dhcp-agent and neutron-metadata-agent can be run with the option of configuring neutron-dhcp-agent availability zones.

The network controller portion of OVN is distributed - an instance of the ovn-controller service runs on every hypervisor. OVN also includes some central components for control purposes.

ovn-northd is a centralized service that does some translation between the northbound and southbound databases in OVN. Currently, you only run this service once. You can manage it in an active/passive HA mode using something like Pacemaker. The OVN project plans to allow this service to be horizontally scaled both for scaling and HA reasons. This will allow it to be run in an active/active HA mode.

OVN also makes use of ovsdb-server for the OVN northbound and southbound databases. ovsdb-server supports active/passive HA using replication. For more information, see: https://github.com/openvswitch/ovs/blob/master/Documentation/OVSDB-replication.md

A typical deployment would use something like Pacemaker to manage the active/passive HA process. Clients would be pointed at a virtual IP address. When the HA manager detects a failure of the master, the virtual IP would be moved and the passive replica would become the new master.

See OVN information for links to more details on OVN’s architecture.