Understanding VPC Flow Logs:
VPC Flow Logs is a feature that captures information about the IP traffic going to and from network interfaces in a VPC. It helps in monitoring and analyzing network traffic, ensuring security, and optimizing network performance.
Current Configuration:
According to the diagram, VPC Flow Logs is already configured for Subnet-1 in the host VPC. This means that traffic information for Subnet-1 is being captured and logged.
Requirement for Subnet-2:
The goal is to monitor flow logs for Subnet-2, which is in the service project VPC.
Correct Configuration for Subnet-2:
To monitor the flow logs for Subnet-2, you need to configure VPC Flow Logs within the service project VPC where Subnet-2 resides. This is because VPC Flow Logs must be configured in the same project and VPC where the subnet is located.
Implementation Steps:
Go to the Google Cloud Console.
Navigate to the service project where Subnet-2 is located.
Select the VPC network containing Subnet-2.
Enable VPC Flow Logs for Subnet-2 by editing the subnet settings and enabling the flow logs option.
Cost and Performance Considerations:
Enabling VPC Flow Logs may incur additional costs based on the volume of data logged. Ensure to review and understand the pricing implications.
Analyze and manage the data collected to avoid unnecessary logging and costs.
Reference:
Google Cloud VPC Flow Logs Documentation
Configuring VPC Flow Logs
Shared VPC Overview
By configuring VPC Flow Logs in the service project VPC for Subnet-2, you ensure that traffic data is correctly captured and monitored, adhering to Google Cloud's best practices.

https://cloud.google.com/router/docs/concepts/overview

https://cloud.google.com/cdn/docs/invalidating-cached-content

Reference:
https://cloud.google.com/interconnect/docs/how-to/dedicated/using-interconnects-other-projects