It’s no secret that data centres are getting the lion’s share of attention in the cabling and networking industry: the rapid growth of this market has been fuelled by new technologies and strong demand as it migrates from proprietary solutions to those incorporating standardized designs and products.

Tipping point

Prior to the release of TIA-942, Telecommunications Infrastructure Standard for Data Centres, there was no central collection of requirements for structured cabling systems in data centres, nor guidelines for their design. The publication of TIA-942 in April 2005, then, was a tipping point for this market. It became the reference in North America for establishing and communicating design requirements, evaluating existing installations and upgrading them in a manner that fostered the: a) use of standard communication applications, and b) implementation of a structured cabling system to replace multiple, incompatible, proprietary solutions and products.

While the standard provides specs for data centre telecom cabling, pathways and spaces, it also opened the door to new technologies that allow for design and installation efficiencies optimized for these environments. Accordingly, the industry is trending away from the ad hoc growth of point-to-point cabling that leads to pathway confusion and documentation errors, and moving toward modular cabling with high-density connectivity (even as data rates migrate to 10 Gb/s and beyond) while considering initiatives for reduced power and ‘green’ design.

New technologies

A quick review of TIA-942 reveals several references to technologies that were new at the time the document was published and have since become mainstream. For example:

• High termination density can be achieved using multi-fiber
  increments and the use of multi-fiber connectors
• If cable lengths can be accurately pre-calculated, pre-terminated multi-fiber ribbon assemblies can reduce installation time
• High data-rate end equipment may accommodate multi-fiber
  connectors directly

Multi-fiber connectivity and cabling is not new: since the introduction of small form factor duplex connectors and the release of the 12-fiber MPO array connector in the late 1990s, optical fiber connectivity density has been steadily increasing in patch panels and transceivers. MPO array connector ferrules house 12 fibers in a 1x12 array, allowing for a single connector about the size of a simplex (one-fiber) SC connector. Higher-density MPO connectors available today can house up to 72 fibers in a 6x12 array in the same form. So instead of 24 rack units (RUs) of space for 288 duplex ports, MPO connectivity consumes less than 1/4 RU.

The MPO connector has empowered pre-terminated optical fiber cable deployments. The high density of fibers in a cable couples nicely with their density in MPO connectors, enabling the rapid deployment and connection of even very-high fiber count cables. In data centre installations—where rack and cabinet locations tend to be placed in a consistent, organized manner—the use of pre-terminated cabling becomes a much simpler exercise, since the location of equipment and pathways makes it easy to determine distances between connected locations.

Field-terminating fiber connectors in the data centre has become an outdated technology, as pre-terminated solutions offer significant reductions in installation time—up to 96% less time compared with field-terminating a 960-port installation. The overall installation costs (products and labour) of pre-terminated solutions are cost-effective and are, in many cases, less than traditional methods. Even so, many data centre managers select pre-terminated solutions simply because of the faster time to go-live operations (not to mention a lower security concern because fewer people spend less time in restricted areas).

The advantages of high-density connectivity have not been lost on OEM electronics vendors, either. Next-generation, high-density electronics are starting to arrive with MPO interfaces on the front rather than bulky SC- or ST-style connectors as the equipment interface. Not only does this save on space and enable the same electronics to fit in a smaller box, blade or chassis, but it also provides benefits in power consumption.

Not just for optical fiber

High-density copper connectivity became reality shortly after TIA-942’s publication, as evidenced by the MRJ21 connector. This connector provides 24-pair connectivity in a footprint similar to two RJ-45 modular connectors. Instead of 12 RUs of space for 288 RJ-45 ports, MRJ21 connectivity consumes only six RUs. Just as the MPO empowered pre-terminated optical fiber cabling, the MRJ21 connector provided a pre-terminated copper solution.

The combination of MRJ21 connectivity with 25-pair copper cabling provides a compact, easily deployed six- or 12-channel solution for data centre networks. Again, field-termination is simply outdated. The MRJ21 has made an even larger impact on electronics vendors; in the past eight months or so, many of them have released products with MRJ21 interfaces.

Cluster (high-performance) computing is necessary in academic or commercial research, and high-density connectivity and electronics have become instrumental in controlling capital expenditures and reducing operational expenses for these installations. Space savings and lower power consumption become key factors in justifying the purchase of new equipment. Since each MRJ-21 cable delivers six 1 Gb/s connections, there are no cluttered RJ-45 cables to block airflow or complicate moves and changes. Now, 1536 (not just 768) Gigabit Ethernet ports come off a 33 RU chassis, consuming 93 amps for 1536 ports instead of 116 amps).

Solving problems with high-density connectivity

Voxeo Corp. is an Orlando, Fla.-based company delivering solutions for speech recognition, Interactive Voice Response (IVR) and VoIP telephony. It has multiple hosting centres in the United States and Europe, but its speed of server installation and manageability was limited by the unruly cabling required to support the operation. Using 84 servers per rack—each with 2-gig Ethernet NICs—meant a lot of cable.

Using the traditional four-pair RJ45 solution was impractical due to the sheer cable volume and time to complete installation. Even multi-connector patch panels took 40 manhours to install, and the fact the connections were hard-wired meant there was little flexibility once the cables were punched down. Adopting the MRJ21 connectivity solution solved the problem in only 1 RU. The server presents a much cleaner appearance and is installed faster, and retains the flexibility needed for moves, adds and changes.

Beyond fibers and wires

One particular clause in TIA-942 addresses data centre administration: “All cabling, cross-connects and patch cords should be documented using spreadsheets, databases, or programs designed to perform cable administration”.

In fact, effective cabling system documentation is required for Tier 3 or 4 data centres. And while there’s no practical, easy way of verifying a system’s documentation, consider this: even 80% accurate documentation will only be 20% accurate after five years. (Just think about the expense and effort required to return 20% accurate documentation to 100% accuracy.) The consequences of inaccurate documentation in today’s litigious and competitive environment can be punitive; accordingly, automated cabling management systems are being deployed to aid in administration.

These systems provide accurate, real-time records and logs that facilitate the timely troubleshooting, repair, security, use-tracking and compliance of the network infrastructure. Using a simple system of contacts and software, the system promotes efficient utilization and inventory of panels, switches, connections and cabling. The software also provides a streamlined work order process with simplified scheduling, planning, record-keeping, accountability and troubleshooting. The real-time information is a critical element for compliance initiatives and security, as well as enforcement of company policies for the use of—and modifications to—the structured cabling network.

Segregation in co-located facilities

It is common to find multiple networks in an end-user’s facility; in many cases, these separate networks are used for working on different problems. While these implementations make sense, outfitting each network with its own data centre is cost-prohibitive as well as inefficient. A single data centre—with its redundant systems, personnel, and security—makes better sense for most installations. However, certain issues arising from ‘co-location’ need to be addressed; specifically, the likelihood that separate networks might inadvertently be connected.

Improper connections can pose security/compliance risks, and penalize efficiency. A simple, elegant solution is the use of connectors, adapters and cable assembly designs with non-standard slots and keys that stop incorrect connections (‘secure’ connectivity). The mating slot/key combinations are colour-coded to enable a visible check on the mate-ability, and to assist in the construction and operation of the networks. Today, secure connectivity for data centre networks is available in RJ-45, LC and MT-RJ connectors—as well as MPO.

Greening up the data centre and the bottom line

Virtualization and multicore processors are driving dramatic increases in cabinet density. Demand for electricity is outpacing production, and the cost just keeps rising. In 2006, servers in the United States consumed $14 billion in power and cooling, and that number is projected to go to $50 billion in 2009. Along with other ‘green’ issues—such as reducing the use of hazardous substances—power consumption is driving data centre decisions.

Fortunately, many new technologies are efficient and, as such, eco-friendly. High-density connectivity, as discussed above, translates to reduced power consumption. High-density copper cabling is smaller than the equivalent number of four-pair cables, resulting in smaller cable bundles that impose fewer restrictions on airflow and less impact on the cooling load. Shielded cabling, with its higher resistance to alien crosstalk, may only need 25% of the power required to run an unshielded 10G Ethernet port. Optical fiber networks may offer the lowest power consumption on a per-port basis of any technology, particularly multimode systems.

Other considerations can have a measurable impact as well. Optimize the data centre’s layout above the raised floor, alternating hot and cold aisles to maximize the cooling system’s efficiency. Be sure to use the recommended blanking and top panels, and solid sides for the racks and cabinets to ensure proper airflow. Below the raised floor, minimize the profile of cables and pipes, eliminate underfloor obstructions and protect the static pressure by sealing unmanaged openings. Power distribution equipment, which generates significant heat, should be placed outside of the data centre.

From a materials perspective, using a lead-free, RoHS (restriction of hazardous substances) product set is an environmentally sound decision. Many of the modular, pre-terminated solutions already satisfy this initiative while also being reusable and re-deployable—saving cost while earning additional green points. (Today, this same strategy is being applied to electrical power distribution, with modular electrical cabling systems that allow for quick and easy relocation of electrical loads and outlets without reconstructing the electrical power network.)

Today’s data centre

Using TIA-942 helps ensure a data centre project is designed, specified and constructed well. Meantime, the proper use of new connector, cabling and power technologies can result in additional benefits. Rest assured, data centre innovations won’t stop now. For example, watch for a new multimode fiber type (predictably called ‘OM4’) to support 40G and 100G Ethernet, and for parallel multimode fiber links rather than the duplex links commonly deployed today. Also, new addenda are being prepared for the data centre standard and a revision of this document is likely in the next year as well.

Working closely with your cabling vendor can be an effective way to stay ahead of the technology curve and keep your data centre modern—even into the future.

Herbert V. Congdon II, P.Eng., is the systems market manager with Tyco Electronics, AMP NETCONNECT, and can be reached via e-mail at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Reprinted with full permission of Network & Cabling Magazine  www.networkcablingmag.ca