Simplifying inter-building high-count fiber networks

Conventional high-count fiber network options are prone to disruptions, increased financial costs due to maintenance, and premature system overhauls. Not surprisingly, users in many industries have begun to explore alternative approaches for their high-count fiber networks.

As the demand for bandwidth continues to proliferate on campuses of all types, many network managers struggle with how to implement fiber backbones that support current data requirements and yet are reconfigurable to suit future needs.

The challenge, of course, is that for many of these campuses – multi-building complexes such as hospitals, corporate centers, government facilities, and universities – future needs can't be accurately predicted. A common response to this uncertainty is the use of high-count fiber-optic backbone cabling systems. Architectures with fiber counts of 144 and 288 are not uncommon, and installations with even higher numbers are emerging.

Unfortunately, many network managers and installers find themselves disappointed and frustrated with conventional high-count cabling and connectivity. High fiber count cables with a large outer diameter are inflexible and hard to manage and install; their bulk risks broken fibers and jeopardizes the success of the system. This reality, combined with connectivity based on stacks of splice trays that feed adapter plates with extremely high fiber counts, can make for an infrastructure that is very challenging to service or to execute moves, adds, and changes.

Moreover, conventional implementations intended to enhance versatility, and thereby overcome this shortcoming, can easily lead to systems with too many connectors in the communications channel. This crowding causes increased attenuation, decreased bandwidth throughput, and general degradation in signal integrity. Stacks of splice trays that must be manipulated to access a single fiber can disrupt the entire network every time service is performed.

Ultimately, conventional high-count fiber network options are prone to disruptions, increased financial costs due to maintenance, and premature system overhauls. Not surprisingly, users in many industries have begun to explore alternative approaches for their high-count fiber networks.

A new "blade-like" approach

One such alternative, known as a "blade system," supports the use of flexible cable subgroups that protect the installer from damaging the fiber during the installation process, as well as a connectivity system that provides easy access to every fiber, without disrupting peripheral fibers during servicing.

The approach also features a unique "blade-like" splicing system. In fact, blade connectivity is "splice-centric." It uses an "in-line flow" of individual fiber subgroups that provides slack storage, splicing, and access to industry-standard couplers, all in a form factor that can be easily accessed from either the front or back of rack-mount chassis and wall-mount enclosures.

Each of the fiber subgroups can be accessed independently of all other subgroups, as there is no arbitrary stack of splice trays located behind a wall of adapter plates. The result is an organized, accessible, high-performance, and dense network system.

And new cable

Blade systems are frequently paired with flexible, high-density, riser-rated, and rugged high-count (HC) fiber cable with a very small diameter. Such HC cable contains tight-buffered fiber units, each of which consists of 12 fibers encapsulated by a matrix material and then surrounded by a tightly bound buffer material. Each of the 12 tight-buffered fiber units is 2 mm in diameter. The resulting fiber-optic cable is relatively small, very rugged, and complete with a lot of fibers.

This design can reduce the outer cable diameter by 20% or more compared to cables with similar fiber counts. However, the cable remains extremely rugged, with good mechanical (crush and flex) and environmental characteristics. Unlike traditional ribbonized cables, the HC cable has no preferential bend, making it flexible for tight bends and much easier to work with and splice. Thus, each of the 12 tight-buffered fiber units can be easily routed into a blade system enclosure for splicing or can be terminated with MTP or MPO connectors for patching.

Taken together, blade systems and their associated HC cables can directly integrate with existing networks or passive optical LANs. Installers can patch into the network with jumpers from the switch right into the blade system. The result is high-quality channel performance from building to building that should fulfill both current and future infrastructure needs.

Dr. Ian Timmins is vice president of engineering, Enterprise Connectivity Products, at Optical Cable Corp.

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