Contrail Cloud High-Level Architecture Overview
Contrail Cloud is a software package that arrives with detailed descriptions of how networking should be established on servers running in the topology and the options available for configuring the software running on the servers. The Contrail Cloud package establishes the storage, compute, and control nodes as well as the connections between these devices. These node functions and their interconnections are covered in greater detail later in this document. The Contrail Cloud package provides additional functionality beyond storage, compute, and control node setup, including Contrail Networking to provide an SDN Controller and Red Hat Openstack to provide an orchestrator.
Figure 1 illustrates a representative Contrail Cloud high-level architecture.
The server nodes—the storage, compute, and control nodes, as well as the bare metal servers (BMS) in environments supporting bare metal servers—are established using Contrail Cloud. These nodes also contain a variety of interconnections to one another and to the EVPN-VXLAN fabric to support multiple functions. See Contrail Cloud Hardware Nodes.
For more detailed information about connecting the storage, compute, and control nodes to the fabric, see Contrail Cloud Configuration in Reference Architecture for Contrail Cloud 13.1 and 13.2.
The fabric network in this representative architecture is a Clos fabric composed of spine and leaf switches. The switches run their own software—they are typically Juniper switches running Junos OS software—and the fabric itself is provisioned using Contrail Networking. See Data Center: Contrail Enterprise Multicloud for Fabric Management and Contrail Networking Fabric Lifecycle Management Guide for information on fabric provisioning and management.
The SDN Gateway routers in this architecture are layer 3 devices that connect to the spine devices in the EVPN-VXLAN fabric. The routers are responsible for all traffic exiting and entering the tenant overlay networks. The scope of configuring the SDN gateway router is beyond this guide. For a sample external gateway router configuration connecting to spine devices in EVPN-VXLAN fabrics, see the Data Center Interconnect Design and Implementation section of the Data Center Fabric Architecture Guide.