We present ez-Segway, a decentralized mechanism to consistently and quickly update the network state while preventing forwarding anomalies (loops and blackholes) and avoiding link congestion. In our design, the centralized SDN controller only pre-computes information needed by the switches during the update execution. This information is distributed to the switches, which use partial knowledge and direct message passing to efficiently realize the update. This separation of concerns has the key benefit of improving update performance as the communication and computation bottlenecks at the controller are removed. Our evaluations via network emulations and large-scale simulations demonstrate the efficiency of ez-Segway, which compared to a centralized approach, improves network update times by up to 45% and 57% at the median and the 99th percentile, respectively. A deployment of a system prototype in a real OpenFlow switch and an implementation in P4 demonstrate the feasibility and low overhead of implementing simple network update functionality within switches.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We would like to thank the anonymous reviewers and our shepherd Jia Wang for their feedback. We are thankful to Xiao Chen, Paolo Costa, Huynh Tu Dang, Petr Kuznetsov, Ratul Mahajan, Jennifer Rexford, Robert Soule, and Stefano Vissicchio for their helpful comments on earlier drafts of this paper. This research is (in part) supported by European Union's Horizon 2020 research and innovation programme under the ENDEAVOUR project (grant agreement 644960).