R3C2: Reactive Route and Rate Control for CEE

In order to fully realize the potential of Cloud and High Performance Computing (HPC) applications, significant improvement is required in the cost/performance of data center networks. While recent industry standards such as Quantized Congestion Notification (QCN) for Converged Enhanced Ethernet (CEE) have begun to address this issue, there are still significant problems left open. Therefore we propose two novel source-based adaptive routing schemes for CEE-based networks. First, we develop a basic source-driven Reactive Route Control (R²C²) adaptive routing scheme. In response to congestion notifications, the source activates additional paths to re-route traffic around potential congestion points. Using industry standard VLANs, a source node can effectively control the path choices in the network. This approach goes beyond conventional QCN limitations by replacing its reaction point with a VLAN-based multipath route controller. We thus enable HPC/Cloud applications demanding direct and/or secure access to the network features. Second, we combine R²C² with the QCN reaction point, resulting in the higher performance Reactive Route & Rate Controller (R³C²). In case of persistent or multiple hotspots when VLAN route selection alone is insufficient, the R³C² source will throttle its packet injection rates individually along each congested route of a multipath bundle. Detailed simulations against established data center and HPC benchmarks show the practical benefits in performance and stability.