Premium Tier delivers traffic from external systems to Google Cloud resources by
using Google’s low latency, highly reliable global network. This network consists of an extensive private fiber network with over 100 points of presence (PoPs) around the globe. This network is designed to tolerate multiple failures and disruptions while still delivering traffic.

Standard Tier delivers traffic from external systems to Google Cloud resources by routing it over the internet. It leverages the double redundancy of Google’s network only up to the point where Google’s data center connects to a peering PoP. Packets that leave Google’s network are delivered using the public internet and are subject to the reliability of intervening transit providers and ISPs. Standard Tier provides network quality and reliability comparable to that of other cloud providers.