Data Center Interconnect (DCI)

Long-haul Data Center Interconnect (DCI) refers to the optical connection that transports traffic flow from data center to data center (inter data center connection, as opposed to intra data center connection).  A typical data center hosts thousands of servers and requires terabits of optical transport capacity to share its data with other data centers and the end users.


Long-haul data center interconnection can be achieved in four basic ways, depending on who owns the optical networking equipment and the fiber plant:

  1. Lease a lit wavelength service from a communications service provider;
  2. Purchase a managed network service from a communications service provider; for both ways #1 and 2, there may be a need for a short-distance optical link between the data center site and the communications service provider’s Point of Presence (PoP) where leased long-haul connectivity over a continental or international network is made available; this short-distance optical link can be provided by the data center operator, the communications service provider or a third party;
  3. Build one’s own optical network using dark fiber purchased from a fiber provider (e.g. a dark fiber provider or utility) and operate one’s own optical networking equipment; this what Google did in the US: they have built their own US long-haul network using dark fibers;
  4. Deploy one’s own fiber plant (e.g. a new subsea cable system) and operate one’s own optical networking equipment.


Ways #1 and 2 represent a good business for communications service providers but other players (mostly Internet content providers and multi-tenant data center operators) are more and more massively investing in their own networking equipment, if not their own fibers, in order to build the networks they really need to better serve their activities according to their standards, needs and expectations.