Minimizing Packet Delay via Load Balancing in Clos Switching Networks for Datacenters

We consider unbalanced traffic distribution in a three-stage Clos switching network for datacenters to ensure 100% throughput and minimize traffic delay by balancing bandwidth utilization. Existing traffic scheduling algorithms with packet delay bound guarantee neglect the fact that unbalanced demands may lead to poor bandwidth utilization and thus lead to poor switching performance. To make up these deficiencies, we propose an efficient multiple hops strategy (MHS). MHS can well utilize internal bandwidth of the switch to achieve load balancing. As the first step of MHS, we first propose a naive algorithm AHF (Average Heavy-Traffic First) to decompose the traffic matrix by taking load balancing into account. By shifting and transmitting packets using those empty time slots (i.e., not-yet-utilized slots) in the configurations generated by AHF, the second step of MHS is achieved to minimize packet delay via a better load balancing strategy. Simulation results confirm that MHS outperforms the naive AHF algorithm by effectively reducing packet delay bound guarantee.