Fields of Fiber

    It’s Alive! The Revival of the Data Center Optical Cross-Connect

    Posted by Bill Miller on Apr 26, 2016 9:30:00 AM
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    Pull-Quotes-03.pngAfter a decade of minimal innovation, the data center optical cross-connect market is roaring back to life.

    For years, the primary users for cross-connects were carrier networks and the largest multi-tenant data centers. Now, digital transformation and the explosion of demand in enterprise and colocation data centers is driving optical cross-connect providers to create a new generation of smarter, faster and more flexible products, because tomorrow’s data centers can’t be built with yesterday’s rigid, fixed solutions.

    The optical cross-connect has, in fact, emerged as a key component in the integration of the physical layer into the data center network, granting network administrators visibility and software control of an intelligent physical layer, to better utilize network assets and adapt to changing demands.

    Fiber Mountain is leading the revival of the humble cross-connect, transforming it into a foundational element of new network architectures. The concept of cross-connects is simple and today’s new solutions simplify data center networks. One of our engineers asked me a while ago how customers and industry analysts could be so excited by our Glass Core solution when the key hardware component, the Optical Path Exchange (OPX), is “just a cross-connect.”

    The answer, of course, is that incorporating layer 1 SDN (software defined networking) into an optical cross-connect with dense on-board optics and ultra-low latency enables the instant delivery and provisioning of any-to-any physical fiber-optic connections and the ability to virtualize these connections via software. The Glass Core creates a virtual connectivity fabric which makes data center networks dynamically reconfigurable, with security, speed and accuracy that traditional manual processes cannot match. A new generation of the cross-connect might not be exciting on its own, but the applications it enables are!


    So, how did we get here?

    The Glass Core's OPX is a natural progression in the evolution of the optical cross-connect, a technology that has been developing for more than two decades. Let’s take a brief look at the digital transformation and application of the data center optical cross-connect from its inception in the early 1990s to today.

    A brief history of the cross-connect

    The predecessor of optical cross-connect was the digital cross-connect system, typically based on SONET, which first emerged around 1990. The purpose of the digital cross-connect was to provide network operators with greater control and protection over their networks, and to allow them to better utilize their communications infrastructure by strategically interconnecting low-level TDM streams.

    At this time, digital cross-connects were mostly used for grooming network traffic, which at the time meant switching traffic between circuits. Digital cross-connects allowed carriers to reroute traffic quickly and cost-effectively.

    The first major breakthrough in digital cross-connect technology can be traced back to 1991, when Tellabs introduced the SONET-based TITAN 5500 Cross-connect. The TITAN 5500 switched internal and external circuits, allowing traffic to flow between networks. While Tellabs was not the first provider to enter into this space, the TITAN proved to be a superior and revolutionary product, putting Tellabs on the map and making the company a top telecommunications vendor of the time.

    The age of the digital cross-connect plateaued.

    The optical era begins

    As effective as these early digital cross-connect systems were, they had some major drawbacks:

    • They were big.
    • They were bulky.
    • They were hard-wired.
    • They were expensive.

    By the late 1990s, the market again shifted and these digital cross-connects became obsolete. Along with the emergence and proliferation of the IP network came fiber optic technology and the advent of the optical cross-connect.

    One noteworthy company that burst onto the scene was Tellium (now Zhone), which formed as a joint venture between Science Applications International Corporation (SAIC) and Ortel. In 1998, Tellium released the Aurora 32 optical cross-connect—a path-switched network built with arcs and nodes and meant for use in high-capacity telecommunications, government and enterprise-grade networks.

    The primary purpose of the Aurora 32, with its 80 Gbps switching capacity and 32 bi-directional ports, was to establish an optical “mesh” network capable of continuously routing network traffic through alternate nodes and fiber infrastructure.

    As impactful as these optical cross-connects were, however, they too had drawbacks. First and foremost, they lacked adequate intelligence. They were also limited by lack of scalability and manual cabling and provisioning processes which were time consuming and prone to human error. For these reasons, much of the original hype surrounding optical cross-connects stagnated.

    Fast forward to today

    The demand for intelligent optical connectivity has now reached a fever pitch. Networks of all sizes are becoming increasingly congested and workloads are becoming denser, pushing network performance expectations through the roof. One study, for instance, shows that workload density—workloads per physical server—for cloud data centers will increase from 5.1 in 2014 to 8.4 by 2019.


    Businesses today are looking to reduce space and power consumption in their networks while increasing flexibility and control, which requires new, more agile network architectures. The new generation of optical cross-connects are playing an integral role in this process, and just as Tellabs turned heads over 20 years ago, Fiber Mountain is attracting similar attention today with the award-winning Glass Core. Our solutions, which have now been selected as Best of Interop finalists at Interop Las Vegas for two consecutive years, add automation and agility to the physical layer of the network and enable a variety of new applications and improvements to old processes.

    Two use cases where the Glass Core is proving to be highly effective are test lab automation and in colocation data center meet-me-rooms, where the technology is used in conjunction with our new CrossCage Plus automated cross-connect solution. CrossCage Plus allows for the delivery and provisioning of cross-connect services to colocation tenants in a matter of minutes, as opposed to the days or weeks that are typical. This on-demand connectivity also opens the door to a broad range of new applications within the multi-tenant data center ecosystem.

    Want to learn more about how the Glass Core can help your business with its digital transformation needs? If you’re heading to Interop, stop by booth 144 and meet our team. You can also email

    Learn More about the Glass Core

    Topics: OPX, automated cross connects, Optical Cross Connects