Best First Fit (BFF): An Approach to Partially Reconfigurable Hybrid Circuit and Packet Switching

Abstract

Hybrid switching for data center networks (DCN) has received considerable research attention recently. A hybrid-switched DCN employs a much faster circuit switch that is reconfigurable with a nontrivial cost, and a much slower packet switch, to interconnect its racks of servers. The research problem is, given a traffic demand (between the racks), how to properly schedule the circuit switch so that it removes most of the traffic demand, leaving little for the slower packet switch to handle. All existing solutions make a convenient but unnecessarily restrictive assumption that when the circuit switch changes from one configuration to another, all input ports have to stop data transmission during the reconfiguration period. However, the circuit switch can usually readily support partial reconfiguration in the following sense: Only the input ports affected by the reconfiguration need to pay a reconfiguration delay, while unaffected input ports can continue to transmit data during the reconfiguration. In this work, we propose BFF (best first fit), the first solution to exploit this partial reconfigurability in hybrid-switched DCNs. BFF not only significantly outperforms but also has much lower computational complexity than the state of the art solutions that do not exploit this partial reconfigurability.