Jul 08, 2013

What are the benefits for carriers switching to fiber optic lines?

I know that in the US, certain internet providers are in the midst of upgrading everything to fiber optic as are other parts of the world. I thought regular Ethernet as it is, can support speeds of up to 100 gigabits per second. What makes fiber so much better?

Fiber-optic communication

"The choice between optical fiber and electrical (or copper) transmission for a particular system is made based on a number of trade-offs. Optical fiber is generally chosen for systems requiring higher bandwidth or spanning longer distances than electrical cabling can accommodate.

The main benefits of fiber are its exceptionally low loss (allowing long distances between amplifiers/repeaters), its absence of ground currents and other parasite signal and power issues common to long parallel electric conductor runs (due to its reliance on light rather than electricity for transmission, and the dielectric nature of fiber optic), and its inherently high data-carrying capacity. Thousands of electrical links would be required to replace a single high bandwidth fiber cable. Another benefit of fibers is that even when run alongside each other for long distances, fiber cables experience effectively no crosstalk, in contrast to some types of electrical transmission lines. Fiber can be installed in areas with high electromagnetic interference (EMI), such as alongside utility lines, power lines, and railroad tracks. Nonmetallic all-dielectric cables are also ideal for areas of high lightning-strike incidence.

For comparison, while single-line, voice-grade copper systems longer than a couple of kilometers require in-line signal repeaters for satisfactory performance; it is not unusual for optical systems to go over 100 kilometers (62 mi), with no active or passive processing. Single-mode fiber cables are commonly available in 12 km lengths, minimizing the number of splices required over a long cable run. Multi-mode fiber is available in lengths up to 4 km, although industrial standards only mandate 2 km unbroken runs."

Actually, there are many reasons that ISPs and telecom carriers are upgrading networks to fiber. Fiber is much cheaper, costing approximately 5%, pound for pound, compared to copper. For the same volume of copper, fiber can transfer about 1000 times the data. Fiber doesn’t have the same distance limitations whereas copper begins to lose signal strength after 15 miles or so.

One of the biggest benefits simply lies in the design. Fiber uses light, not electrical current. Though relatively low voltage, copper causes some magnetic interference in large trunks. In some industrial sites, copper actually poses a hazard as it can ignite flammable material in certain scenarios. Fiber also transfers data in a different manner than copper which is more efficient.



Copper networks (not all) use a method of passing data along frequencies called time division multiplexing or TDM. In a basic sense, each frequency is only used for a certain amount of time before a signal is passed to another channel. Fiber uses wave division multiplexing (WDM) where a transmission utilizes a single channel throughout the entire process.


And yes, there are adapters that can handle speeds of up to 100 Gb/s. However, service providers can't maintain these speeds to most locations. Such adapters are mostly used on internal networks to pass data between servers, SANs, routers, etc.

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