Contrail Cloud Integration with OpenStack Overview
Figure 1 illustrates the API-level interaction between OpenStack and Contrail configuration. The Contrail Neutron plug-in enables the OpenStack Neutron service to make the necessary API calls into the Contrail configuration node to create, delete, and update network resources as defined in OpenStack. Contrail configuration node has a northbound interface which exposes REST APIs to orchestration systems such as OpenStack and Contrail Web UI that can be used to make the network configurations.
Figure 2 illustrates a more detailed step-by-step interaction between components of OpenStack services, specifically Nova, Neutron, and Contrail services. At the control plane the Contrail plug-in for Neutron translates the configuration commands received from the northbound orchestration engines into corresponding Contrail-related configuration. On the data plane or forwarding plane, the Nova-agent running on each compute hypervisor interacts with the distributed forwarding engine in Contrail, called the vRouter, to set up a virtual-interface and tap interfaces for VMs to obtain connectivity.