You use Shared VPC: host project contains the VPC network, service projects host VMs. Where must you create the Cloud Router that advertises the Shared VPC network to an on‑prem BGP peer?

Cloud Routers are network-specific resources and must be created within the project that owns the VPC network they are advertising. In a Shared VPC setup, the host project is where the VPC network is defined and managed. Therefore, the Cloud Router must reside in the host project to advertise its routes to an on-premises BGP peer. Creating it in a service project would not work because service projects only consume the shared network, they don't own it. Cloud Router is a project-level resource, not an organization-level resource, and cannot exist in a separate project disconnected from the VPC.