BCN: Bidimensional Compound Networks for Data Centers

A fundamental challenge in data centers is how to design distinguished networking topology for efficiently interconnecting a large number of servers. This paper studies the design of Data Center Networking (DCN) from the aspect of the degree/diameter problem, which determines desirable DCNs that support the largest number of servers given maximum server degree and given diameter. More specifically, we propose the bidimensional compound network (BCN) to interconnect servers with dual ports and low-cost commodity switches. BCN is a level-i irregular compound graph recursively defined in the first dimension for 0≤i, and a level one regular compound graph in the second dimension. In each dimension, a high-level BCN employs a one low level BCN as a unit cluster and connects many such clusters by means of a complete graph. A BCN of level one in each dimension is the largest known DCN with server degree 2 and diameter 7, and is large enough for a single data center. In addition, BCN has many attractive features, such as low diameter, constant server degree, high bisection width, supporting of incremental expansion, and good fault-tolerance ability. Mathematic analysis and comprehensive simulations show that BCN possesses excellent topology properties and is a viable interconnection structure for data centers. To the best of our knowledge, this is the first work studying the degree/diameter problem in data centers.