ExpressRoute lets you securely add compute and storage capacity to your existing datacenter. With high throughput and fast latencies, Azure will feel like a natural extension to your datacenter, so you enjoy the scale and economics of the public cloud without having to compromise on network performance. "With Microsoft Azure ExpressRoute, we are now able to provide near-limitless virtual expansion to existing datacenters, redundant connections, streamlined network engineering, consistent performance, and improved security to an organization of 124,000 employees worldwide."