Resource Management in Hybrid (Wired/Wireless) Data Center Networks

Routing and resource allocation are key challenges in hybrid data center networks. Ensuring an efficient management of wireless and wired infrastructure in the hybrid (wired/wireless) data center networks (HDCN), for both one-hop and multi-hop communications, is primordial to guarantee a high performance network. In one-hop inter-rack communications, the sending and receiving racks are placed in the same wireless transmission range, the objective is to find efficient algorithms for wireless channel allocation in HDCN while minimizing the congestion level. Several recent research approaches have explored the feasibility of deploying wireless links in HDCN based on practical testbeds, but only few studies have been conducted to perform wireless channel allocation. On the other hand, the multi-hop inter-rack communications require efficient mechanisms to jointly route and allocate channels for the communication flows, while enhancing network performance. The objective is to compute for each flow, the hybrid (i.e. wireless and/or wired) routing path. In this regard, the joint routing and wireless channel allocation problem in HDCN can be addressed either in an online or a batch way. In the online mode, inter-rack communication flows are sequentially processed in order to find the hybrid routing path for each single flow request. Few research works have been proposed to deal with this issue. However, even if the online approaches guarantee an optimized hybrid routing path for each single flow request, they fail to ensure an optimized use of the wireless and wired resources in the HDCN. Indeed, the arrival order closely impacts the HDCN performance. Therefore, a few recent researches have investigated the joint batch routing and channel ( JBRC ) assignment problem in HDCN, to handle the batched arrivals of communication flows. Their objective is to find, for each batch of flows, the corresponding hybrid routing paths. In this chapter, we will review the different routing and wireless resource allocation strategies in HDCN. For the sake of completeness, we first give a brief description of the above problems and their challenges in HDCN. Then, in the second section, we will give an in-depth overview of the wireless channel allocation approaches dealing with one-hop inter-rack communications in HDCN. Next, we introduce the major joint online routing and channel allocation strategies for multi-hop communications in HDCN. Afterward, the main JBRC allocation algorithms dealing with the batched arrival of inter-rack flows are detailed. Then, we will present a qualitative comparison between the different related resource allocation and routing strategies in HDCN. Finally, we summarize this chapter.