VCN: Versatile Clos-Type Networks for Traffic Locality in Data Centers

Traffic locality is ubiquitously exploited in today's data centers. It allows network resources to be used more efficiently because traffic in data centers is adapted to the underlying network infrastructures. In this paper, we approach this problem from another direction, which is to adapt network infrastructure to the traffic. Towards this direction, we adopt two approaches to boost the efficiency of network resource utilization. First, we improve the topology of Clos-type data center networks by introducing horizontal connections, which facilitates the routing of local traffic. Second, based on the improved topology, we make the network infrastructure to be versatile, in the sense that it can be fitted into the characteristics of the traffic. We name this design as Versatile Clos-type Networks (VCN). We describe the topological architecture of the VCN, design its addressing and routing schemes, and demonstrate its various properties. We also evaluate its performance and compare it with fat-tree, a representative Clos-type data center network architecture. The evaluation results show that the VCN can deliver the same throughput as fat-tree, but use significantly reduced network resources.