Underlying network provides infrastructures for cloud computing in data centers. The server-centric architectures integrate network and compute, which place routing intelligence on servers. However, the existing multi-port server based architectures suffer from determined scale and large path length. In this paper, we propose FleCube, a flexibly-connected architecture on multi-port servers without using any switches. FleCube is recursively constructed on division of multiple ports in a server by means of complete graph. FleCube benefits data center networks by flexible scale and low diameter, as well as large bisection width and small bottleneck degree. Furthermore, we develop multi-path routing (MPR) to take advantage of parallel paths between any two servers. MPR adopts random forwarding to distribute traffic load and relieve network congestion. Analysis and comparisons with existing architectures show the advantages of FleCube. Evaluations under different degrees of network traffic demonstrate the merits of FleCube and the proposed routings. 
FleCube: A flexibly-connected architecture of data center networks on multi-port servers