FIG. 3 illustrates an exemplary cloud provider network 203 including geographically dispersed provider substrate extensions 224 (FIG. 2A) (or “edge locations 303”) according to some embodiments. As illustrated, a cloud provider network 203 can be formed as a number of regions 306, where a region 306 is a separate geographical area in which the cloud provider has one or more data centers 309. Each region 306 can include two or more availability zones (AZs) connected to one another via a private high-speed network such as, for example, a fiber communication connection. An availability zone refers to an isolated failure domain including one or more data center facilities with separate power, separate networking, and separate cooling relative to other availability zones. A cloud provider may strive to position availability zones within a region 306 far enough away from one another such that a natural disaster, widespread power outage, or other unexpected event does not take more than one availability zone offline at the same time. Customers can connect to resources within availability zones of the cloud provider network 203 via a publicly accessible network (e.g., the Internet, a cellular communication network, a communication service provider network). Transit Centers (TC) are the primary backbone locations linking customers to the cloud provider network 203 and may be co-located at other network provider facilities (e.g., Internet service providers, telecommunications providers). Each region 306 can operate two or more TCs for redundancy. Regions 306 are connected to a global network which includes private networking infrastructure (e.g., fiber connections controlled by the cloud service provider) connecting each region 306 to at least one other region. The cloud provider network 203 may deliver content from points of presence (PoPs) outside of, but networked with, these regions 306 by way of edge locations 303 and regional edge cache servers. This compartmentalization and geographic distribution of computing hardware enables the cloud provider network 203 to provide low-latency resource access to customers on a global scale with a high degree of fault tolerance and stability.
