DevoFlow

TLDR

OpenFlow provides flow‑level control and global visibility but incurs high overhead from frequent switch‑control‑plane and controller interactions, limiting its suitability for high‑performance networks. This work analyzes those overheads and proposes DevoFlow, a modified OpenFlow model that reduces control‑plane coupling while preserving useful visibility. DevoFlow decouples control from global visibility, allowing the switch to handle most traffic locally and reducing controller involvement. Simulations show DevoFlow load‑balances data‑center traffic as effectively as fine‑grained solutions while using 10–53× fewer flow‑table entries and 10–42× fewer control messages.

Abstract

OpenFlow is a great concept, but its original design imposes excessive overheads. It can simplify network and traffic management in enterprise and data center environments, because it enables flow-level control over Ethernet switching and provides global visibility of the flows in the network. However, such fine-grained control and visibility comes with costs: the switch-implementation costs of involving the switch's control-plane too often and the distributed-system costs of involving the OpenFlow controller too frequently, both on flow setups and especially for statistics-gathering. In this paper, we analyze these overheads, and show that OpenFlow's current design cannot meet the needs of high-performance networks. We design and evaluate DevoFlow, a modification of the OpenFlow model which gently breaks the coupling between control and global visibility, in a way that maintains a useful amount of visibility without imposing unnecessary costs. We evaluate DevoFlow through simulations, and find that it can load-balance data center traffic as well as fine-grained solutions, without as much overhead: DevoFlow uses 10--53 times fewer flow table entries at an average switch, and uses 10--42 times fewer control messages.