Optical local area networks (OLAN) will cause you to rethink practically everything you have learned about LANs and LAN cabling. Of course, any major change in technology like this causes FUD (fear, uncertainty and doubt), just like voice-over Internet protocol (VoIP) and Wi-Fi have already.
VoIP integrated voice into data networks and shares cabling, meaning only one cabling system is needed, therefore simplifying installation. Wi-Fi was scary until contractors realized that wireless access points needed cabling and power. In the case of OLANs, it’s not just the new technology and single-mode fiber that is scary; it’s the fear of losing all the work installing giant bundles of Cat 5e/6/6a cable and all the associated hardware, such as racks and cable trays. (Like many others in the industry, I lazily refer to all these versions of category-rated unshielded twisted-pair (UTP) cables as “Cat 5.” So where I write Cat 5, I mean the whole group of category-rated UTP cables.)
OLANs—which need only a single fiber cable to the work area, replacing eight or more Cat 5 cables—will indeed cut down the number of cables installed. However, it means installing one cable that will bring premium prices instead of eight cables at commodity pricing. It also means installing the splitters needed to create the passive LAN network. And at the end of each of those fibers, one needs a small fiber-to-Cat 5 switch that will require mounting and power. It will reduce time spent testing, troubleshooting and fixing problems. Profitability should improve. Jobs will go faster.
Contractors have adapted quickly to these new networks, often taking on more of the networking equipment installation work in addition to the cabling. For many contractors I talked with, adapting was easy because they had already been installing distributed antenna systems in large buildings, which use the same single-mode cabling technology.
Designing OLAN cabling structures is not difficult. There are far fewer cables involved, and they are smaller and lighter—all those good things you have heard about fiber optics for a long time—so cable trays are smaller, if needed at all. Some building owners may prefer fiber cable to be installed in ducting for protection, but even so, the structures required are much simpler than a copper network. Ducting is an especially good idea in an upgrade if the OLAN is being installed and then the older structured cabling is removed. The possibility of damage to the new fiber optic cable when removing the old copper is greatly reduced when installed in bright orange ducting.
Part of the design must include the location of the splitters that are used to create the passive network. It’s best to place them closer to the user switches to reduce the length of fiber optic cable required, so they are often installed in the telecom rooms where the switches would normally be mounted. Splitters are available in rack-mount versions that can be mounted next to fiber optic patch panels. Other versions are available for mounting above ceilings or on walls or other structures where the National Electrical Code allows.
At the user work area, you need space for a work area switch called an optical network terminal (ONT) that provides gigabit Ethernet outputs for several users (typically four). These ONTs, about the same size as a DSL or cable modem, can be mounted on walls or on or under desks. Some even fit in a standard wall box. The ONT needs power, usually provided from the same supplies as the connected devices. It needs to be conveniently mounted so the user can reach it to connect their Cat 5 patchcord, the only copper in the whole system.
If the user’s device also requires power—as would a wireless access point or VoIP phone—the ONTs used in OLANs offer options for power over Ethernet (PoE). Local PoE is much more efficient since the resistive losses of a short patchcord is much less than 100 meters of horizontal cabling.
Transitioning to this new technology is simplified by using the support of vendors that have developed appropriate products and trained staff members to assist contractors. Now is the time to begin learning about OLANs from these manufacturers, as they have all been promoting the advantages of this new technology, especially cost, heavily to their customers and probably yours, too.
You need to be prepared for when customers start asking you about OLANs, so you can discuss the technology intelligently with them. Learn about the differences in design between an OLAN and traditional structured cabling and how it differs in installation—a subject that will be this column’s topic for next month.