Data Center Interconnection – Not Quite So Simple

Rick Talbot
Rick Talbot

Summary Bullets:

  • Data center interconnection (DCI) transport is emerging as potentially a massive optical transport opportunity.
  • Regardless of the often-quoted demand for a simple point-to-point DCI transport solution, some applications are likely to be better served with a packet-optical solution.

DCI has become somewhat of a darling of the optical transport networking world. Once Facebook explained that most of the traffic that connects to its data centers (which is approximately 10% of the data flow within the data centers) came from other data centers, the market perceived that DCI would be a very big business, perhaps ultimately as large as all of telco transport. Simultaneously, many data center operators claimed that their requirements for DCI were not complex; all that was needed was to provide high-capacity/density and low-cost/power point-to-point connections between the data centers. In fact, some web-scale companies such as Microsoft and Google proposed a concept of do-it-yourself (DIY) transport in which the data center operator would purchase and assemble optical components to achieve a highly cost-effective DCI transport solution. Optical systems vendors, after fretting about losing out on this new DCI business segment, realized that this application actually presented them with a high volume (albeit at low margin) opportunity on top of their existing business. Some of the more nimble of those vendors quickly developed and introduced customized DCI transport platforms – Infinera’s Cloud Xpress, Cyan’s (now Ciena’s) N-Series, Ciena’s WaveServer and ADVA’s CloudConnect. After this mad dash to introduce products to address the point-to-point DCI application, perhaps it is time to examine the data center transport marketplace with a bit more perspective.

Most data center operators not only lack the scale of a Google or Facebook, but they also tend to operate a different data center business model. The primary Internet content providers (ICPs) tend to be the sole occupant of their data centers, and they employ a data center architecture that aggregates and grooms all of the site’s traffic, sending massive data flows to adjacent (whether across the metro or across the globe) data centers. However, for economic and business reasons, a larger portion of data center operators host a number of customers in each site, and carrier-neutral providers, such as Equinix, TELX and Pacnet (now owned by Telstra), base their businesses on serving numerous clients in each data center. Though the largest clients in these multi-client data center operators may have DCI transport demand that justifies a 100 Gbps wavelength (or even an emerging 200G wavelength) simple point-to-point DCI model, in other cases individual client flows do not nearly utilize that level of capacity. In this case, the data center operator needs to aggregate and groom the client traffic and distribute it over multiple transport wavelengths. This application calls for an optical transport platform with packet switching capabilities (a packet-optical transport platform).

Demand for switching in data center connection applications is reflected in ongoing packet-optical transport platform traction and in data center operator statements, including a recent statement made by CyrusOne in a press release (<a href=>CyrusOne Expands Global Data Center Interconnect Network Footprint with BTI Systems</a>), which asserted that its choice of BTI’s 7800 Series Intelligent Cloud Connect for DCI was based, in large part, on its packet switching capability. Similarly, a quantitative analyst firm announced in April 2015 that Alcatel-Lucent, Ciena and Infinera were DCI market share leaders; this leadership was based on packet-optical transport platforms, not the custom DCI transport platforms, all but one of which had yet to ship.

Thus, DCI is no less complex than the architectures and business models of the data centers being interconnected. In many cases, data center operators will find the switching capabilities of a packet-optical transport platform compelling. In other cases, the scale of massive DCI data flows will call for simple transport in as large of a data channel as available. The good news for optical networking vendors is that both applications are likely to present significant opportunities.


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