As mentioned previously, some Cloud Providers with data centers located close together stretch the workload resource of a single vCloud Director instance across separate sites. Previously, a number of network “round-trip delay” configuration maximums constrained Cloud Providers’ ability to stretch services across separate locations unless those locations were very close together. While stretching service across separate locations offers a degree of independence from a single location, it leaves a dependence upon either inter-site connectivity to bridge a “remote” site to resources in its “parent” location, or, complex networking and support designed to lessen the connectivity dependence. However, the advantage that stretching offers is the simplification of customer or management operation. Even though the underlying technology is more complex, the provider and customer gain the ability to manage services in multiple data centers as if they were in one location. VMware Cloud Providers have used two different topology models to achieve this, sometimes in combination. The two models are examined in the following sections.