When diagnosing latency issues that are suspected to be a Google Cloud platform issue, the Network Intelligence Center Performance Dashboard is the recommended tool. It provides visibility into network performance metrics across Google Cloud, including inter-region latency, which can help confirm if the increased latency is due to a platform-wide issue rather than specific to your VPC or application. While Connectivity Tests are useful for verifying reachability and basic network configurations, and tcpdump is for in-instance packet analysis, neither provides the broad, platform-level visibility needed to assess general Google Cloud network performance trends and baselines.

Exact Extract:

"The Performance Dashboard in Network Intelligence Center helps you visualize network performance metrics for your Google Cloud network, including inter-region latency and packet loss. It provides insights into the health of the Google Cloud network and can help you identify if performance degradations are due to the underlying platform."

"The Performance Dashboard provides an aggregated view of network performance across Google Cloud, allowing you to compare your current latency with historical trends and Google Cloud's overall network performance."Reference: Google Cloud Network Intelligence Center Documentation - Performance Dashboard