You peer Sales↔Finance and Marketing↔Finance VPCs, but users cannot reach resources across Sales↔Marketing. How do you resolve this connectivity issue?

VPC Network Peering is non-transitive, meaning if VPC A peers with VPC B, and VPC B peers with VPC C, VPC A and VPC C cannot communicate directly through VPC B. To enable communication between all three VPCs (Sales, Finance, and Marketing), you must establish direct peering connections between every pair. This is known as a full mesh configuration. Altering the routing table won't resolve the fundamental non-transitive nature of VPC peering. Network tags are for firewall rules, not for establishing connectivity between VPCs. Deleting and recreating the network is an extreme and unnecessary measure, as transitive peering is not a feature of Google Cloud VPCs.