OpenStack Virtual Networks with Routers

Virtual Routers are used to communicate to different virtual network. As soon as Tenant adds the subnet associated virtual network to router, doing this will creates a port on virtual router and is associated to IP address of the gateway for that subnet.

The Default Layer 3 plugin is used to implements the virtual router using Linus Namespace and these namespaces has its own network configuration, Routing table, Packet forwarding tables.

Configuring Routing Service:  

In order to provide the routing service, Neutron server must be configured with router service plugin. This can be achieved by following:

To do this, update the service plugin list in Neutron configuration file /etc/neutron/neutron.conf:

[DEFAULT]
service_plugins = router

The router plugin implements virtual router instances using Linux namespaces. This is done using the L3 agent deployed on the network node. The router plugin and L3 agent communicate over the message bus. The L3 agent configuration file is present at /etc/neutron/l3_agent.ini: