Passive optical interconnects at top of the rack for data center networks

Limited scalability of the current commodity switches in terms of capacity and power consumption becomes a bottleneck of the development of data center networks. To solve this problem, optical switches have been proposed to interconnect different servers inside the data centers. However, most of such work has focused on core switches, which handle the communications among different racks inside the data centers as well as interfaces to Internet. In fact intra-rack communications dealing with the traffic inside a single rack in the data centers could also take up a substantial proportion of the total traffic in the data center networks, in particular for cloud computing. With this in mind, this paper proposes novel architectures based on passive optical interconnect at top of the rack (ToR) for data center networks inheriting the advantages of passive optical network (PON) technologies. With reliable and stable passive optical components, intra-rack communications can be realized in an optical domain rather than the conventional electrical switches at ToR. In such a manner, our schemes have a great potential to offer higher bandwidth and reduce power consumption. The transmission performance evaluation carried out by both simulation and experiments has verified the feasibility of the proposed architectures for passive optical interconnects.