Data Center Interconnect (DCI)

Data center interconnect (DCI) is a high-capacity network link between two or more data centers for sharing workloads and replicating data. DCI usually runs over dark fiber or leased wavelengths using coherent optics, with common line rates of 100G, 400G and increasingly 800G per wavelength. Metro DCI links between buildings in the same city keep latency low enough for synchronous replication, while long-haul links connect regions for disaster recovery and distributed AI training. Operators of carrier-neutral campuses often sell DCI as a managed service between their own sites. The choice between owning fiber and renting wavelengths drives cost: owned dark fiber has high upfront cost but near-zero marginal cost per added channel.