ClusterLink: Redefining Application Connectivity for the Multi-cloud Era

Modern software development abstracts applications from the underlying infrastructure, enabling global-scale deployment with minimal concern about low-level networking details. However, when these infrastructure-agnostic software components need to communicate, they encounter significant networking limitations. This forces developers to either navigate complex, low-level networking constructs to achieve the desired connectivity or give up on truly flexible connectivity and limit their software to static connectivity patterns. In this paper, we focus on the evolving challenges of application connectivity in today's hyper-distributed reality. We propose to model connectivity around the notion of application services and have realized this proposal as ClusterLink, which exposes the app-level APIs for specifying communication policies at a very granular level and implements them efficiently. This paper shares details on ClusterLink design principles, APIs, architecture, and implementation, and shows that ClusterLink outperforms its closest competitor by 2.5x in throughput in a cloud-based experimental setting.