Critical Issues in Cabling Design

The planning phase is the time to ensure that a structured cabling system will provide flexibility and reliability

By Omar Elissa  

Whether it’s voice, data, video, security or the building management system, information is increasingly critical to the productivity of building occupants and to the performance of the building itself. But the quality of that information flow can be no better than the conduit carrying it — the cabling system. A structured cabling system is designed to ensure that information flows smoothly over the cabling network. It includes a set of transmission products applied with engineering design rules that allow the user to apply voice, data and signals in a manner that maximizes data rates.

The structured cabling system is the foundation of a successful intelligent building network and the basic investment on which all other network equipment depends. A structured cabling system installation is neither vendor-specific nor topology-dependent. It offers uniformity, flexibility, scalability, easy and low cost changes, and investment protection of an asset with a very long life — 10 years or more.

The system has become a common platform for many information technology system types and applications, including telecom (voice and data), building automation, security (CCTV, access control, etc), teleconferencing and in some instances fire alarm. This convergence makes the structured cabling system the most important component of the network and the associated systems, one that merits a serious investment in a highly reliable, flexible and scalable system.

Benefits of a High-performance Network

A structured cabling system divides the entire infrastructure into manageable blocks and then integrates these blocks to produce a high-performance network that serves as the lifeline for most businesses and all data centers. A structured cabling system will support near-future applications with little or no upgrade pain. Unforeseen problems are less likely to bring down an entire network because problems are easier to isolate and correct. And it is easy to test and isolate the specific points of failure and rectify the situation with minimal disturbance to the entire network.

Another advantage of a structured cabling system is that it minimizes the effort required for moves, adds and changes. Such a system also allows for a consistent infrastructure across the network in cases of converged building systems. Consistency yields cost savings by simplifying maintenance procedures, reducing staff needs and increasing reliability.

Moreover, a structured cabling system based on the current standards also provides the flexibility to support a variety of applications and hardware from different vendors. This improves installation, testing and management efficiencies.

Finally, the “structured” nature of such a system facilitates administration and management by providing designated points of distribution, standard labeling and coloring mechanisms and methods, and cabling management and distribution methodologies.

More often than not, data center managers resort to a dynamic approach in populating a data center with IT equipment. This approach has to be employed to accommodate the changing requirements of business operations, which in turn often drive the need for the latest IT equipment. And because businesses depend on IT equipment and infrastructure, top management expects any need for additional IT capacity or capability to be met almost instantaneously.

However, data center managers can react only as fast as the availability of IT equipment and the facility infrastructure allow. In today’s market, vendors can generally supply products very quickly. But, if a data center manager is faced with a poorly designed IT infrastructure, the process can grind to a halt.

Critical Issues

To avoid such a situation, it is essential to address critical structured cabling system issues during the planning phase. Among the most important points to address are these:

  • Service providers. Key steps include identifying the service providers available for the job site; establishing diverse and redundant routes for bringing the service into the facility; coordinating the point of entrance for each respective service provider; accounting for the respective equipment requirements; and allocating space for each service provider. This process will prove essential for improving the fault tolerance of the overall structured cabling system design, as will employing a self-healing optical carrier service such as Synchronous Optical Network (SONET).
  • Telecommunications rooms. Entrance facilities (EF), main distribution frames (MDF) and intermediate distribution frames (IDFs) should allow for 20 percent expansion of equipment.
  • Centralized IDFs. Placing telecommunications IDFs in central locations in the data center enables easy cable management, as well as the efficient addition of future equipment.
  • Adjacencies. Planning for future equipment population and adjacencies facilitates pathway design for expansion space, which in turn provides near-new construction efficiency for future cable installation.
  • High-performance design. A high-performance cabling infrastructure — one that is capable of supporting converged telecommunications needs, including voice, data, video, electronic security and building control — provides optimum return on investment because it can meet current and future infrastructure requirements.
  • Switches. Placing switches in the center of server rows enables easy and cost-effective cable management. It also shortens cable runs, resulting in immediate cost savings.
  • Zone cabling concept. This approach utilizes a “scattered IDFs” design strategy — in other words, specific platforms remain in their designated spaces, rather than being connected to one central IDF. This avoids disrupting the entire data center space when upgrades or changes have to be made to a certain platform.
  • Heat maps. The heat generated by systems such as densely-packed routers and switches, server farms with compact and blade servers, mainframes, storage area networks and automatic tape libraries poses challenges like airflow management. That’s why it’s advisable to develop data center heat maps using equipment power consumption and ventilation requirements. The layout can also be used by electrical and mechanical designers. This coordination leads to an optimal layout to efficiently use space, airflow and electrical distribution.

The planning stage is the time to maximize the flexibility to respond to ongoing changes in equipment planning today and adapt to future technologies. That’s why facility executives should get an IT design engineer (preferably an RCDD — Registered Communications Distribution Designer) involved from the planning stages of a data center project.

An effective design can significantly reduce downtime; minimize moves, adds and changes; and reduce life-cycle costs of the cabling system. In the planning stages of new construction, it is crucial to spend time to address system performance, redundancy, diversity and modularity for the structured cabling system, as well as to anticipate future requirements. A comprehensive design approach will ensure that prudent planning and intelligent design are combined with industry standards. The result will be a cabling infrastructure that has a good chance of staying useful for several years, saving money while providing access to cutting-edge telecommunications solutions.

Omar Elissa, P.E., is a senior telecommunication systems engineer with EYP Mission Critical Facilities Inc. Rakesh Mohan, RCDD, contributed to this article.

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  posted on 8/1/2004   Article Use Policy

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