Cable Management and Slack Storage WHITE PAPER Taking Up the Slack in Cable Management Over the years, more and more people have become experienced in working with optical fiber, particularly in the central office (CO) environment. One bit of knowledge obtained quickly through experience is the importance of fiber cable management and how it can dramatically affect the operational costs of a network. ADC has a wealth of experience in the areas of cable management and slack storage systems that are time-tested and continually improved – but it all begins with pure awareness. Storing excess fiber cable is an often overlooked area within the fiber-to-the-premise (FTTP) network’s outside plant (OSP) architecture, yet it is critical when it comes to preventing cable management problems. For example, excess patch cord fiber is usually necessary for reconfiguring a fiber circuit, but the slack must be managed to prevent damage. At the same time, all fibers should remain as accessible as possible during day- to-day operations of the network. Accessibility and the amount of time required to reconfigure a network will be optimized in a system that maintains a continuous non-coiled or twisted routing of the fibers. The successful slack storage system provides flexible storage capacities, permanent bend radius protection, and easy access to individual fibers. It will also mitigate many potential problems that non-managed systems could face over time. Keys to Unlocking Fiber Management Good fiber cable management can be broken down into a few key principles. The first principle is to develop clear routing paths that are obvious to any technician at a glance. In other words, routing the fiber correctly should be intuitive and easily accomplished. Next, fiber cable should be physically protected to prevent damage as a result of technicians working on other parts of the cabinet or cable management device. Measures should be taken to avoid damaging, pulling, stretching, crushing or pinching existing fibers in the vicinity of the work area. Another key to cable management is bend radius protection. As fiber is bent, the radius can become too small and allow light to escape the core and enter the cladding. The result is insertion loss in the fiber or a macrobend that decreases the signal or, in extreme cases, causes complete signal loss and data transfer failures. Finally, an integrated slack storage strategy or system is necessary. Each fiber, due to the high tolerance needed, is normally terminated in the factory to eliminate the high costs involved with field terminations. This typically results in fixed cable lengths and patch cords. Once the technician arrives at the job site to make a connection, the fiber cable or patch cord may be longer than what is actually required. Therefore, a system must allow the proper storage of the slack – the difference in length between what is actually needed to physically make the connection, and what the technician actually has to work with. Cable Management and Slack Storage Cable Management and Slack Storage Page 3 These storage management principles have evolved within the CO environment for making a network both reliable and operationally efficient. Now that fiber is being pushed deeper into the access network, particularly as fiber-to-the-premise (FTTP) architectures begin to deploy, these same principles will apply to ensure the operational efficiency of the access portion as well. Although many may be less inclined to realize the importance of cable management in the access network due to less data traveling across a single fiber, it’s critical to realize that far more fibers are being deployed in comparison to the core network. Therefore, individual management of fiber becomes even more important since each fiber’s reliability is directly tied to customer satisfaction. CO Techniques Outside the CO Since the fiber distribution hub in the access network’s outside plant is very similar to a CO’s fiber frame device, it makes sense that the same cable management techniques should be put into practice. But since the fiber distribution panel is located in the middle of a neighborhood, environmental issues must also be considered. Additionally, a single technician is likely to have many different responsibilities while not specializing in how a particular piece of equipment operates. This scenario generates an even greater need for effectively dealing with fiber cable management issues. For example, when the technician arrives at the distribution cabinet, he may not be familiar with exactly how previous fiber cables and connections have been made. In fact, it could be the first time he’s opened this particular cabinet. With that in mind, it’s easy to see the importance of a system that not only achieves routing paths that are intuitive, easy to find, and clear, there should also be documentation right at the point of use that enables the technician to remember and implement standard cable management techniques. Outside temperature variations also can cause fiber cable management issues. Although the fiber isn’t affected by fluctuating temperatures, the jacketing materials can shrink and expand, causing bend radius problems. Technicians must ensure all fiber cables are constrained around the bend radius while permitting shrinkage in cold temperatures. Other less common scenarios, yet still worthy of consideration, might include the possibility of having to completely restore a fiber distribution cabinet that was struck by a vehicle. Is there a plan in place for quickly restoring or replacing the cabinet? Typically, this involves having some coils of slack storage below the ground or up on a pole that allows replacement of the entire cabinet or modular items within the cabinet. In a typical FTTP architecture, it is often common to place only half the terminations within the distribution cabinet and allow for future expansion. The cable management system should be adaptable to routing any splitter port to any connector port, making it easy to add more connections without affecting the cable management that exists for the original fibers. In fact, the ability to route from any splitter port to any distribution port is a key issue within the cabinet. Making sure the cable management is in place to support the clear routing paths, store slack cable, provide physical protection, and achieve proper bend radius protection from day one to several years after deployment will provide operational cost savings for the service provider. Getting to Every Connector Finally, easy connector access is a vital part of any cable management system. Technicians should be able to access any individual connector for cleaning, maintenance, and troubleshooting. Cleaning connector endfaces is no less important in the access network than in the CO environment. A small speck of dust on an endface can jeopardize a successful optical connection. Since many of the access network connections are made in the outside plant portion of the network, there is wind and contaminants to raise the probability of an exposed endface attracting debris. Therefore, cleaning both the front and rear connections in the panel is necessary and requires adequate access. Dust covers on the connectors and adaptors are designed for keeping debris off the endface, but they are always dependent on how technicians use them. Dust covers never negate the need for cleaning each time a connection is made. Typically, some slack fiber is left on the backside of a patch panel in the event of a failed or broken connector or fiber. This enables the opportunity to restore service to the cabinet by having extra fiber to use. There should be a place for storing a number of splices and a way to access that area – along with extra slack cable that enables quick restoration when necessary. Fiber cable management techniques play as important a role in the access network as they have traditionally played in the CO. The fiber distribution hub is a particularly crucial area due to the large number of connections and fibers present. However, other areas that deserve consideration for cable management include the fiber access terminals farther up the access network. Here again, the same key techniques apply for cable routing, slack storage, physical protection, and bend radius considerations. Additionally, the optical network terminal (ONT) at the extreme end of the network, although only dealing with one or two fibers, is also a candidate for bend radius and physical protection issues. ADC believes that proper cable management techniques will optimize access networks in terms of accessibility and the amount of time required to reconfigure a network. Successful cable management is key to eliminating many potential problems that non-managed systems will likely face in their future. ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer 103779AE 11/06 Revision © 2005, 2006 ADC Telecommunications, Inc. All Rights Reserved Web Site: www.adc.com From North America, Call Toll Free: 1-800-366-3891 • Outside of North America: +1-952-938-8080 Fax: +1-952-917-3237 • For a listing of ADC’s global sales office locations, please refer to our web site. WHITE PAPER . technician actually has to work with. Cable Management and Slack Storage Cable Management and Slack Storage Page 3 These storage management principles have evolved. Cable Management and Slack Storage WHITE PAPER Taking Up the Slack in Cable Management Over the years, more and more people have