Timeslot Switching-Based Optical Bypass in Data Center for Intrarack Elephant Flow With an Ultrafast DPDK-Enabled Timeslot Allocator

To alleviate the performance interruption between elephant and mouse flows, a combined optical timeslot switching (OTS) and L2/L3 Top of Rack (ToR) architecture is experimentally demonstrated for the first time in a data center scenario. In this system, elephant flows are identified on the fly by a newly built sFlow-based traffic analyzer and delivered through a separate OTS subsystem. In this way, elephant flows are physically isolated from mouse flows; thus, fewer mutual interruptions are expected. However, previous OTS research has not sufficiently addressed how the timeslot allocator and timeslot allocation should be implemented to adapt to traffic fluctuations, and it is obvious that the current SDN-based timeslot allocation cannot satisfy the OTS system's requirements for time efficiency. Therefore, in this paper, data-plane development kit platform was used to enable an ultrafast online timeslot allocator (TSA) that can process timeslot requests at traffic levels exceeding 1 Tb/s. This demonstration employs two Intel Xeon CPU e5 logical cores for TSA, a private protocol between the TSA and servers, and a novel timeslot allocation algorithm. Using the proposed architecture, mouse flows are seldom interrupted by elephant flows. The power penalty of the OTS system is less than 1.2 dB, which is acceptable for server-to-server interconnections. Furthermore, simulation results show that the system achieves a consistently lower end-to-end latency for all flows than does a traditional ToR-based intrarack data center network (DCN).