What is the difference between hub nodes and leaf nodes in oracle RAC database?

Flex cluster is a new architecture option introduced in Oracle 12cR1. And in this option there are two types of cluster nodes; Hub nodes and Leaf nodes.

Hub nodes within the cluster are interconnected with each other with a high-speed interconnect network and have direct access to shared storage. But, leaf nodes are not connected to each other and have no direct access to shared storage of oracle RAC database.

Below are some of the key differences between Hub nodes and Leaf nods:

• The resource requirements for leaf nodes is less compared to Hub nodes.
• Hub nodes contain Database instances, ASM instances, Virtual IP(VIP) services but leaf nodes does not contain these components.
• Leaf nodes does not have direct access to the storage managed by Flex ASM and requires Global naming service(GNS) to discover the Hub nodes.
• Leaf nodes are not interconnected to each other( no private inter-connect between them) but Hub nodes are interconnected.
• Leaf nodes uses the same public and private networks but Hub nodes use different public and private networks.