A scalable multi-stage packet-switch for data center networks

Abstract

The growing trends of data centers over last decades in- cluding social networking, cloud-based applications, services, and storage technologies enabled many advances to take place in the networking area. Recent changes imply continuous demand for bandwidth to manage the large amount of packetized traffic. Clus- ter switches and routers make the switching fabric in a data cen- ter network (DCN) environment. They are employed to provide in- terconnectivity between elements of the same DC and inter DCs. To handle the constantly variable loads, switches need deliver outstanding throughput along with resiliency and scalability for DCN requirements. Conventional DCN switches adopt crossbars or/and blocks of memories in multistage interconnection architec- tures (commonly 2-tiers or 3-tiers). However, current multistage switches, with their space-memory variants, are either too complex to implement, have poor performance, or not cost effective.We pro- pose a novel and highly scalable multistage switch design based on networks-on-chip (NoC) fabrics for DCNs. In particular, we de- scribe a novel three-stage Clos-network packet-switch fabric with a round robin (RR) packets dispatching scheme where each central stage module is based on a unidirectional NoC (UDN), instead of the conventional single-hop crossbar fabric. The design, referred to as Clos-UDN, overcomes all the shortcomings of conventional mul- tistage architectures. In particular, the Clos-UDN switch: (i) Ob- viates the need for a complex and costly input modules, by means of few, yet simple, input FIFO queues. (ii) Avoids the need for a complex and synchronized scheduling process over a high number of input-output modules and/or port pairs. (iii) Provides speedup, load balancing, and path-diversity thanks to a dynamic dispatching scheme as well as the NoC based fabric nature. Extensive simula- tions are conducted to compare the Clos-UDN switch to some mul- tistage switches. Results show that the Clos-UDN outperforms con- ventional designs under different input traffics, making it highly appealing for ultra-high capacity DC networks.