Overview
Using BGP knobs to eliminate asymmetric routing and effectively utilize multiple links between on-premise and cloud environments.
While many companies operate entirely in the cloud, even more do not. As great as cloud computing is, it takes a very specific use case to justify a 100% cloud deployment—typically very small companies, with highly variable workloads that are principally API or software driven. For the rest of us, we need to sort out the optimal way of connecting our on-premise data centers with cloud resources. This means traffic engineering, and often, BGP. If you thought BGP was reserved for hyper-scalers and service providers, think again.
BGP (Border Gateway Protocol)
BGP is the routing protocol that stitches the Internet together. Traditionally, not many people outside of service providers may have had use of it. But increasingly, BGP is seen inside the data center, particularly as an overlay routing protocol used in spine-leaf clos fabrics. It’s also what you have to use if you want to peer with AWS DirectConnect, Microsoft Azure ExpressRoute, or Google Connect. BGP has a lot of knobs—that is, way to control path selection and route advertisement—but we’re only going to focus on two of them: local preference (to influence outbound routing to the cloud from your on-prem) and AS path (to influence routing to your on-prem from the cloud).