OTMEN: Offloading Traffic Monitoring to Edge Nodes in Software-Defined Datacenter Networks

Network traffic monitoring is an essential component of many SDN applications, especially in the datacenter environment, where tenants' applications are often distributed over the computing resources. The conventional SDN procedures for flow-level monitoring force the network controller to install fine-grained forwarding rules on switches for the initiated flows, and they rely on the pull-based mechanism to collect traffic statistics from the network switches. Such an approach overwhelms the controller and faces challenges when deployed in datacenter networks, which can have millions of distinct active flows per second. Therefore, in this paper, we introduce the design and implementation of OTMEN, a scalable traffic monitoring system for SDN-enabled datacenter networks. OTMEN decouples the forwarding and monitoring configurations in the data plane to relax the controller, while allowing fine-grained flow-level monitoring at the edge switches. In the OTMEN system, the controller can offload traffic monitoring operations to edge nodes based on the monitoring rules as it provides a rich set of RESTful APIs for monitoring applications. We evaluated our proposed system on a realistic testbed, and the results show that OTMEN provides significant improvements and monitoring overhead reduction compared to the existing solutions.