In June 2019, Oracle and Microsoft announced a cloud interoperability partnership where customers can run mission-critical enterprise workloads across Microsoft Azure and Oracle Cloud Infrastructure (OCI) by directly connecting the nearby OCI and Azure regions through a privately owned network. This interconnection connects OCI FastConnect directly with Azure ExpressRoute without an intermediary network provider. It provides a dedicated, highly available, low latency, and high-bandwidth connection that enables customers to run their workloads spread across the two clouds.
As a general practice, customers deploy their various infrastructure environments and applications across multiple virtual cloud networks (VCNs) for resource isolation and better manageability. It can easily become a nightmare from the manageability perspective, if all the VCNs connect to either the on-premises environment or Microsoft Azure. You couldn’t attach multiple VCNs to a single DRG. To overcome that limitation, customers used hub-and-spoke topology to establish connectivity between Microsoft Azure and multiple VCNs and subnets in OCI.
The following diagram shows the high-level architecture diagram, and the detailed setup is already available for deploying the private interconnection using the hub-and-spoke topology.
The recently announced feature under OCI Networking includes attaching multiple VCNs to a single dynamic routing gateway (DRG). Previously, to achieve a similar setup, deploying hub-and-spoke topology was the only possible solution. Using the new feature, you can attach a single DRG to multiple VCNs directly and connect multiple VCNs through a single private interconnection to Azure.
The following graphic shows the new architecture:
As you can see, the newer capability removes the need of a hub-and-spoke topology if multiple VCNs require connecting to Azure resources. You can use a single private interconnection to serve multiple VCNs on OCI, with deploying multiple interconnects each terminating at individual VCN.
For more information on the interconnection, see the following references:
Principal Cloud Architect at Oracle, focusing on Databases, Cloud-Native Architecture