Connecting building-to-building: Exploring the fiber option

As recently as the early 1990s most computers lacked network connections of any kind. Dialup modems were painfully slow, the Internet hadn't caught on yet ...

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From the November, 2013 Issue of Cabling Installation & Maintenance Magazine

Why the medium makes sense in campus environments.

By Susan Stanley, B&B Electronics

As recently as the early 1990s most computers lacked network connections of any kind. Dialup modems were painfully slow, the Internet hadn't caught on yet, and unless you were employed by a university or the military you probably had no use for email. The office and industrial networks that did exist tended to be relatively small, and 10-Mbit/sec connections over coaxial cable were fast enough and reliable enough for the applications of the day.

Fast forward to the present. Both the size and complexity of local networks have grown exponentially. We're not just connecting a handful of PCs in a single building anymore; quite often we're connecting hundreds of network nodes located in a variety of different buildings.

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One example of mode-conversion capabilities can be shown in the case of a Canadian university, which installed a 10G switch at its satellite campus, and mode converters at both switches, to accommodate the transfer of data-intensive student records between the two sites.

Network equipment was primarily designed for small local area networks (LANs), and as a result copper cabling was--and still is--widely deployed. It's inexpensive, it's easy to use and when combined with switches and routers it lets network designers create fairly complex LANs and connect those networks to the outside world via the Internet. When a network is located in a controlled environment, and the network isn't large, copper cabling is quite reliable.

But copper cable has many drawbacks, especially when you take it off the desktop and out into the real world. Ethernet cable has an effective range of only 100 meters. It's vulnerable to factors like signal degradation and line noise. And it can provide an easy entry point for hackers.

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Medical campuses can make use of 10G bandwidth, including singlemode-based systems, to rapidly transmit files such as MRI scans and x-ray images.

So more and more network designers are installing fiber-optic cable, not just as Ethernet backbone, but all the way to the desktop. Fiber is immune to electromagnetic interference (EMI) and electrical transients. It provides far more bandwidth than copper cable. It's more secure. And whereas copper cable has its 100-meter range limit, fiber-optic cable can cover distances up to 100 kilometers. And fiber doesn't just make a network more rugged and reliable; its incredible bandwidth ensures that the network will be able to handle the more-robust applications that will appear in the future.

Applications are already gobbling up more and more bandwidth, especially when there's a need to move large amounts of data over long distances. Gigabit (1G) speed is barely enough these days, and 10G is becoming the new norm. Businesses and organizations like Internet service providers (ISPs), medical centers and large universities are already moving to 10G. A decade ago an ISP's typical customer did a bit of Web surfing and emailing. Now that same ISP must be able to support bandwidth-hungry applications like online gaming and streaming video. As the cost of fiber continues to drop, and as the need for bandwidth continues to increase, fiber is replacing copper in more and more applications.

Worthwhile investment

Fiber has many virtues. We've already discussed its 100-km range, electromagnetic immunity and enhanced security. Now let's take a closer look at its bandwidth. Om3 and Om4 multimode fiber, as well as singlemode fiber, will support 10G speeds right out of the box. Installers choose the fiber type according to the results of a cost/benefit analysis. Short-wavelength transmission systems supported by multimode fiber are less expensive, but are limited to a range of up to 2 km. These systems are very cost-effective for LANs and campus building-to-building applications. Long-wavelength systems supported by singlemode are more expensive, but have ranges up to 100 km. These systems typically are used to connect cities, wide area networks and other big-data-over-distance applications for which only singlemode can do the job.

Fiber supports different wavelengths and speeds, and it also supports different protocols. So no matter what kind of network is in use--Ethernet, Fibre Channel, Asynchronous Transfer Mode (ATM) or Modbus for example--fiber can support it. If the network device at the fiber interface provides Simple Network Management Protocol (SNMP), fiber can also be managed and monitored. If a backhoe or other piece of heavy equipment comes along and cuts your fiber connection, SNMP will alert you to the fault location.

Getting comfortable with fiber

Fiber used to have a reputation for being difficult to terminate and for being fragile during installation. Those issues have been resolved in recent years. The new termination kits make things much easier, and you can purchase your fiber prebundled in groups of 24 strands or more, housed in PVC or other connection types. You can also get it bundled with copper cabling. Some installers like to pull both kinds of cabling, thus offering their customers additional flexibility. Modern fiber has high tensile strength and it can tolerate a bend radius of up to 1 inch in diameter.

Stories about fiber optics damaging eyes or equipment fall into the category of urban legends. Fiber interfaces fall into the Class I, eye-safe lasers category, although peering into a fiber's transmit port is discouraged. (See sidebar.)

Fiber can survive wide temperature extremes. It can also provide redundancy. Due to the number of strands in a fiber bundle, fiber can provision multiple customers and it can also be used to provide a smaller number of customers with dual fiber lines that can be connected to separate endpoints to establish a failsafe condition.

Connecting to copper devices

A simple media converter will normally provide the interface between copper and fiber cable. Media converters are available in a variety of speeds and fiber types, and they're not expensive. They don't add any significant latency and they don't interfere with the data transmission. Media converters often have a copper and fiber interface to connect the copper-based switches over to fiber--literally linking Point A to Point B. Dedicated fiber-based switches can provide some of that conversion, but at a much higher cost.

When a network already has one kind of fiber installed, and there's a need to connect to a different type, you can do that easily with a fiber mode converter.

Mode conversion in action

One of our customers, a Canadian university, needed to transfer data-intensive student records from its main campus to a satellite campus location. The university had already invested in local 10G fiber infrastructure using multimode fiber. But connecting the two locations would require singlemode, with its long-range capability, and the 10G fiber-based switch at the main campus supported multimode fiber. A pair of ordinary mode converters and a second 10G switch solved the problem. B&B installed a mode converter at each end of the singlemode connection, converting multimode to singlemode and back again at 10G speed. The remote campus received the second 10G switch, and the connection between the main campus and its satellite was seamless. By investing in fiber the university made its network future-ready and ensured secure data transmission.

Medical campuses are also making use of 10G bandwidth and its ability to transmit large amounts of data in real time. Physicians, for example, often need quick access to data from nearby labs, like MRI results and x-ray images. The file sizes can be very large. 1G used to be considered excellent bandwidth, but doctors don't want to wait for hand-carried x-rays and CDs anymore. They want to see results in minutes, rather than hours or days. So 10G is rapidly becoming a requirement.

An entire team of experts may be involved in designing a fiber infrastructure installation. But it will be the installer's job to ensure that everything is installed and working properly. And the installer will be the first point of contact when data transmission fails. Even if he or she is not an expert in every single aspect of data networking, the installer will prove their worth by knowing where to turn when advice is needed. You'll be in good hands if your cable installer works with a fiber vendor that provides ongoing technical support.

There are many ways to connect network equipment. Your needs will be determined by factors like the size of the network, the equipment involved, speeds required, the distance to be covered and, inevitably, your budget. Bear in mind, however, that a large part of the cost of any network installation will be the labor, and the higher price of fiber will ultimately be offset by its superior capabilities. Fiber can help you design reliable, cost-effective new network infrastructure, expand or upgrade existing infrastructure, and prepare yourself for the increased need for bandwidth that we can expect to see in the very near future.

Susan Stanley is training manager at B&B Electronics (www.bb-elec.com). She has spent the past 18 years in engineering and customer service at technology-related companies.


Laser-based systems and eye safety

The author points out that stories of laser-based communication systems damaging eyes fall into the realm of urban legend. In its Reference Guide to Fiber Optics, the Fiber Optic Association (www.thefoa.org) addresses this issue as well. That document tells us: "Many people are concerned that the most dangerous part of fiber-optic work was the chance you might get your eyeballs burned out by laser light in the fiber. They had confused optical fibers with the output of high-powered lasers used in labs. Or perhaps they had been going to the doctor to get warts burned off their skin using lasers with fiber-optic probes, or even seen too many science fiction movies.

"In fact," the FOA continues, "most fiber-optic systems do not have sufficient power to cause harm to your eyes and the light coming out of a fiber is expanding, so the farther away you are from the end of the fiber, the lower the exposure. Having said that, consider yourself warned. In more recent times, some fiber-optic systems are carrying sufficient power to be dangerous and some fiber-optic inspection techniques increase the chance of harm."

That information appears in the Reference Guide's section titled Fiber Optic Safety, which discusses eye safety as well as the safety precautions necessary when handling bare fiber.

-Patrick McLaughlin

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