255Tbps: World’s fastest network could carry all of the internet’s traffic on a single fiber

Last Updated on Sunday, 14 February 2016 10:27 Written by wearefaster Sunday, 14 February 2016 10:27

A joint group of researchers from the Netherlands and the US have smashed the world speed record for a fiber network, pushing 255 terabits per second down a single strand of glass fiber. This is equivalent to around 32 terabytes per second — enough to transfer a 1GB movie in 31.25 microseconds (0.03 milliseconds), or alternatively, the entire contents of your 1TB hard drive in about 31 milliseconds.

To put 255Tbps into perspective, the fastest single-fiber links in commercial operation top out at 100Gbps, or 2,550 times slower. 255Tbps is mindbogglingly quick; it’s greater, by far, than the total capacity of every cable — hundreds of glass fibers — currently spanning the Atlantic Ocean. In fact, 255 terabits per second is similar to — or maybe even more than — the total sum of all traffic flowing across the internet at peak time.

How did the researchers at Eindhoven University of Technology (TU/e) and University of Central Florida (CREOL) do it? Multi-core fiber, of course! As it stands, the entire internet backbone consists of single-mode glass and plastic fiber. These fibers can only carry one mode of light — which, in essence, means they can only carry the light from a single laser. (It’s a bit more complex than that, but it’s beyond the scope of this story to explain it any further.) You can still use wavelength division multiplexing (WDM) to push insane amounts of data down a single fiber (a few terabits), but we will eventually run up against the laws of physics.

Multi-core fiber — literally a strand of optical fiber that has multiple cores running along it — allows for multi-mode operation. It has historically been hard (and costly) to make high-quality multi-mode fiber, but it seems those barriers are finally starting to fall. In this case, the TU/e and CREOL researchers used a glass fiber with seven individual cores, arranged in a hexagon. They used spatial multiplexing to hit 5.1 terabits per carrier, and then WDM to squeeze 50 carriers down the seven cores — for a total of 255Tbps. This wasn’t just a short-range laboratory demo, either: The multi-mode fiber link was one kilometer (0.62 miles) long. [Research paper: doi:10.1038/nphoton.2014.243]

(The image at the top of this story is DARPA’s multi-core photonic-bandgap fiber — not the seven-core fiber used in the research discussed here.)

Eventually, multi-mode fiber will most likely replace the internet’s current single-mode backbone — but considering such an upgrade would require millions of miles of new multi-core cabling, and lots of new routing hardware to handle the multi-mode connections, we’re talking very long-term here. Still, with internet traffic continuing to grow at an alarming rate — mostly fueled by the popularity of streaming video, and smartphones and tablets bringing billions more people online — it’s nice to know that we now have the necessary technology to make sure that we don’t run out of bandwidth any time soon.


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About Internet Speed

Last Updated on Sunday, 14 February 2016 10:16 Written by wearefaster Sunday, 14 February 2016 10:16

The bit rates for dial-up modems range from as little as 110 bit/s in the late 1950s, to a maximum of from 33 to 64 kbit/s (V.90 andV.92) in the late 1990s. Dial-up connections generally require the dedicated use of a telephone line. Data compression can boost the effective bit rate for a dial-up modem connection to from 220 (V.42bis) to 320 (V.44) kbit/s.[13] However, the effectiveness of data compression is quite variable, depending on the type of data being sent, the condition of the telephone line, and a number of other factors. In reality, the overall data rate rarely exceeds 150 kbit/s.[14]

Broadband technologies supply considerably higher bit rates than dial-up, generally without disrupting regular telephone use. Various minimum data rates and maximum latencies have been used in definitions of broadband, ranging from 64 kbit/s up to 4.0 Mbit/s.[15] In 1988 the CCITT standards body defined “broadband service” as requiring transmission channels capable of supporting bit rates greater than the primary rate which ranged from about 1.5 to 2 Mbit/s.[16] A 2006 Organization for Economic Co-operation and Development (OECD) report defined broadband as having download data transfer rates equal to or faster than 256 kbit/s.[17] And in 2015 the U.S. Federal Communications Commission (FCC) defined “Basic Broadband” as data transmission speeds of at least 25 Mbit/s downstream (from the Internet to the user’s computer) and 3 Mbit/s upstream (from the user’s computer to the Internet).[18] The trend is to raise the threshold of the broadband definition as higher data rate services become available.[19]

The higher data rate dial-up modems and many broadband services are “asymmetric”—supporting much higher data rates for download (toward the user) than for upload (toward the Internet).

Data rates, including those given in this article, are usually defined and advertised in terms of the maximum or peak download rate. In practice, these maximum data rates are not always reliably available to the customer.[20] Actual end-to-end data rates can be lower due to a number of factors.[21] Physical link quality can vary with distance and for wireless access with terrain, weather, building construction, antenna placement, and interference from other radio sources. Network bottlenecks may exist at points anywhere on the path from the end-user to the remote server or service being used and not just on the first or last link providing Internet access to the end-user.


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What is Latency?

Last Updated on Sunday, 14 February 2016 08:03 Written by wearefaster Sunday, 14 February 2016 08:03

Latency is a time interval between the stimulation and response, or, from a more general point of view, as a time delay between the cause and the effect of some physical change in the system being observed.[1] Latency is physically a consequence of the limited velocity with which any physical interaction can propagate. This velocity is always lower than or equal to the speed of light. Therefore, every physical system that has spatial dimensions different from zero will experience some sort of latency, regardless of the nature of stimulation that it has been exposed to.

The precise definition of latency depends on the system being observed and the nature of stimulation. In communications, the lower limit of latency is determined by the medium being used for communications. In reliable two-way communication systems, latency limits the maximum rate that information can be transmitted, as there is often a limit on the amount of information that is “in-flight” at any one moment. In the field of human–machine interaction, perceptible latency has a strong effect on user satisfaction and usability.


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