The VPC network peering allows private (RFC 1918) connectivity across two VPC networks that can span over multiple projects and even multiple organizations. In an organization with multiple network administrative domains, VPC peering allows for services to be available across VPC networks in a private IP space. These organizational services can also be exposed to other organizations via this private space. VPC network peering has more advantages than using public IP addresses or VPNs to connect organizations or networks with latency, and exposure to public internet being one of the most important ones. Also, when networks are peered, there are no egress traffic costs, which saves on overall network costs.
VPC network peering works with compute engine and app engine flexible environments. Routes, firewalls, VPNs, and other traffic tools are applied independently...