Network Expansion of Regional DCIs: Optical Circuit Switching Versus Electrical Packet Switching

Recently, the regional data center interconnect (DCI), which is a large-capacity network data-center (DC) cluster to provide low latency and high bandwidth network services, has attracted noticeable interests from DC operators. However, the network planning for regional DCIs is challenging and existing studies only considered how to build a regional DCI from scratch. In this paper, we study how to optimize the expansion of an existing regional DCI that is based on electrical packet switching (EPS), such that the capital expenditures (CAPEX) of the network expansion can be minimized. We consider both EPS-based and optical circuit switching (OCS) based expansions to find out which one is more beneficial for CAPEX saving. Two integer linear programming (ILP) models are first formulated to tackle the EPS-based and OCS-based expansion approaches exactly, and then two heuristics are proposed by leveraging an auxiliary graph based iterative approach. Extensive simulations compare the EPS-based and OCS-based expansions in various scenarios, and our results suggest that OCS-based expansion is more cost-efficient regardless of the settings of scenarios.