SD-MAC: Design and evaluation of a software-defined passive optical intrarack network in data centers

With rapid development of cloud computing services, traffic in data centers (DCs) increases dramatically. Top-of-rack Ethernet switches dominate network cost and energy consumptions in DCs. Optical switching technologies have been introduced into DC networks to increase switching capacity and to reduce energy consumption. However, how to design high-performance optical intrarack networks is still a great challenge. This paper presents a software-defined passive optical intrarack network (SD-POIRN) based on optical coupler fabrics. The data plane of SD-POIRN is a broadcast-and-select optical network combining wavelength division multiplexing and time division multiplexing technologies. The control plane of SD-POIRN has a centralized rack controller for scheduling intrarack data transmissions. This paper proposes a software-defined media access control (SD-MAC) protocol for SD-POIRN. The SD-MAC utilizes dynamic transmission and receiving server grouping methods and max-min fair share bandwidth allocation algorithms to dynamically allocate bandwidth among servers in an efficient and fair manner. Network performance evaluation results show that, when the offered load is high, the proposed SD-MAC protocol effectively increases network throughput and reduces average packet delay compared with previous works.