Network Connectivity Center provides full mesh connectivity between each spoke that has the data transfer feature enabled. If all spokes have the feature enabled, Network Connectivity Center propagates all routes that one spoke learns to all other spokes.
In the preceding topology, Spokes A, B, and C are attached to the same hub and use Cloud Router to advertise prefixes into the hub.
To enable cross-region site-to-site traffic through hubs and spokes, you must enable global routing in the VPC network associated with the hub and spokes. If all spokes are located in the same region, then global routing isn't necessary because site-to-site traffic works without enabling global routing.
The following table shows how the hub propagates prefix advertisements to other spokes.
| Routes from Spoke A | Routes from Spoke B | Routes from Spoke C | |
|---|---|---|---|
| Routes exported to Spoke A | 10.3.0.0/16 is reachable through Spoke B. | 10.4.0.0/16 is reachable through Spoke C. | |
| Routes exported to Spoke B | 10.2.0.0/16 is reachable through Spoke A. | 10.4.0.0/16 is reachable through Spoke C. | |
| Routes exported to Spoke C | 10.2.0.0/16 is reachable through Spoke A. | 10.3.0.0/16 is reachable through Spoke B. |
What's next
- To view a sample topology, see Sample topology for site-to-site data transfer.
- To learn about high availability requirements, see High availability requirements for spoke resources.
- To work through a tutorial, see Connecting two sites by using Cloud VPN spokes.
- To create hubs and spokes, see Work with hubs and spokes.
- To view a list of partners whose solutions are integrated with Network Connectivity Center, see Network Connectivity Center partners.