Data-centric publish/subscribe routing middleware for realizing proactive overlay software-defined networking

Software Defined Networking (SDN) has emerged as an attractive solution to allow cloud-to-cloud interconnection and federation. SDN technologies, such as OpenFlow, use both reactive hop-by-hop and proactive approaches to program the switches. The reactive strategy incurs substantial scalability problems for large networks due to the hop-by-hop behavior while the proactive approach is hard to implement in practice due to the need to forecast all possible forwarding rules ahead-of-time. An attractive and more realistic alternative is the proactive overlay SDN approach, however, many challenges must first be overcome to realize it. Existing techniques to program the switches use low-level programming abstractions, which are error-prone and cannot scale. Middleware-based solutions, e.g., using XMPP, are stateful and hence also incur substantial scalability issues. Although content-based publish/subscribe (pub/sub) solutions have been used in the past for SDN, they rely on brokers, which is problematic and incurs unnecessary additional infrastructure elements that pollute the SDN architecture. To address these issues, this paper demonstrates how the strengths of the data-centric, broker-less pub/sub paradigm can be exploited to realize proactive overlay SDN for inter cloud domain federation. To that end, we first present the design rationale and architecture of our solution called POSEIDON (Proactive brOkerless SubscribEr Interest-Defined Overlay Networking). Second, we present the messaging protocol between the controller and switches. Finally, we present results of evaluating POSEIDON and illustrate how it improves data delivery and provides high performance at the network-level in proactive overlay SDN.