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Zhang, Peng, Li, Hao, Hu, Chengchen, Hu, Liujia, Xiong, Lei, Wang, Ruilong, Zhang, Yuemei.  2016.  Mind the Gap: Monitoring the Control-Data Plane Consistency in Software Defined Networks. Proceedings of the 12th International on Conference on Emerging Networking EXperiments and Technologies. :19–33.

How to debug large networks is always a challenging task. Software Defined Network (SDN) offers a centralized con- trol platform where operators can statically verify network policies, instead of checking configuration files device-by-device. While such a static verification is useful, it is still not enough: due to data plane faults, packets may not be forwarded according to control plane policies, resulting in network faults at runtime. To address this issue, we present VeriDP, a tool that can continuously monitor what we call control-data plane consistency, defined as the consistency between control plane policies and data plane forwarding behaviors. We prototype VeriDP with small modifications of both hardware and software SDN switches, and show that it can achieve a verification speed of 3 μs per packet, with a false negative rate as low as 0.1%, for the Stanford backbone and Internet2 topologies. In addition, when verification fails, VeriDP can localize faulty switches with a probability as high as 96% for fat tree topologies.

Qiao, Siyi, Hu, Chengchen, Guan, Xiaohong, Zou, Jianhua.  2016.  Taming the Flow Table Overflow in OpenFlow Switch. Proceedings of the 2016 ACM SIGCOMM Conference. :591–592.

SDN has become the wide area network technology, which the academic and industry most concerned about.The limited table sizes of today’s SDN switches has turned to the most prominent short planks in the network design implementation. TCAM based flow table can provide an excellent matching performance while it really costs much. Even the flow table overflow cannot be prevented by a fixed-capacity flow table. In this paper, we design FTS(Flow Table Sharing) mechanism that can improve the performance disaster caused by overflow. We demonstrate that FTS reduces both control messages quantity and RTT time by two orders of magnitude compared to current state-of-the-art OpenFlow table-miss handler.