The document discusses the importance and characteristics of high-speed data cables in networking, including optical fiber, coaxial, and twisted-pair cables. It highlights trends in data speeds, challenges in cabling design, and the need for energy efficiency in data centers. The conclusion emphasizes that all three cable types have future applicability depending on specific networking needs and technological advancements.

1. KupferTek
High-Speed Data Cables
Energy-efficient, high-speed data connections
for data centers and local area networks
Kevin Krizman
KupferTek
Wayne, PA USA

2. KupferTek
What is “High Speed”?
• High speed is a relative term, but ideally if the data rate of the network connection is
faster than devices (computers) on the ends of the connection, and the latency is
small, then to the user it does not matter if data is stored locally or somewhere in the
“cloud”.
• For network designers, it is also important that the data “pipes” are big enough to
handle the offered traffic. If the connections are too slow for the amount of traffic,
there will be delays, connection timeouts, and frustrated users.
• For application developers, the ability to send and receive the necessary data
structures (voice, video, sensor data, historical records, authentication and
authorization requests, etc.) within the required timing limitations can also determine
what is high speed and what is not.

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What are data cables?
• Data cables are signal- or waveguides that carry information
encoded as electromagnetic signals from one place to another.
• Common data cable formats:
– Optical fibers
– Coaxial cables
– Twisted pair wires
Optical fiber Coaxial cable Twisted pair cable

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Why is the choice of data cable important?
• Because connectivity in modern networks is (still) complex!
• There are many practical technology, engineering, and economic
factors to consider. A typical data signal is physically transformed
multiple times during its trip through the network.
• Example…

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Trends in end-user data speeds
• End-user bandwidth continues to increase by about 50% per year.

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Trends in global Internet data speeds
• Global Internet bandwidth growth is slowing (for now), but the growth is still
substantial.
• End user bandwidth growth is at present faster than core network bandwidth
growth. If this trend continues, the pressure points will be at the aggregation
points in the network and in the network core.

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Data cable considerations
• Data speed or “bandwidth” of individual links as well as the overall data capacity of
the data centers and networks are (still) growing rapidly.
• The main choices for data cables in many common applications are optical fiber,
coaxial, or twisted-pair cables.
• The questions for the network and data center designers are:
– Which cabling solution provides me with adequate data capacity for today
and the next generation in all segments of the network?
– Which has the best reliability?
– Which has the lowest life-cycle costs?

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Optical Fiber
• An optical fiber data cable is a strand of composite glass covered with
one or more protective jackets.
• The “core” of the fiber is a thin strand of glass with a high refractive index
that carries information signals as light pulses.
• The “cladding” is a doped glass tube with a lower refractive index than
the core that contains the information signals within the core.

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Types of optical fibers
• Most optical fiber data cables are 125μm in diameter (not
counting the external jackets and armor)
• The cores are 62.5, 50, or 9μm in diameter.
• Fibers with 62.5 and 50μm cores are called “multi-mode”
• Fibers with a 9μm core are called “single-mode”

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Optical fiber technologies
Courtesy Simeon Corp.: http://files.siemon.com/share-white_papers-pdf/13-06-24-light-it-up-optical-fiber-media-transmissions-applications.pdf
Typical light sources for fiber optic cable Fiber optic types and standards
Typical color coding

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Optical fiber speeds and ranges
Typical fiber speeds and supported distances, for given fiber types
Courtesy Simeon Corp.: http://files.siemon.com/share-white_papers-pdf/13-06-24-light-it-up-optical-fiber-media-transmissions-applications.pdf

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Important fiber characteristics
• Purity of the core glass—reduces amplitude loss and physical dispersion of the
signal.
• Surface quality/transition between core and cladding—reduces signal dispersion
promotes maximum speed transmission.
• Precision and polish of the connectors and splices—enables reliable
transmission/reception of the signal at each end of the fiber cable. Light reflections
and losses need to minimized.
• What limits the speed and performance of optical fiber cables?
– Pulse generation of the lasers—shorter pulses = faster data
– Absorption loss in the cable—less absorption = longer transmit distances
– Dispersion in the cable—less dispersion lower interference between pulses = faster data and/or longer
transmit distances

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Advantages of fiber optic cable
• Excellent for long-distance transmission
• Noise immunity
• Extremely high data speed potential
https://www.aflglobal.com/Products/Fiber-Optic-Cable/ADSS.aspx
Typical outdoor cable for
WAN distribution

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Coaxial cable
• A coaxial cable consists of a round center conductor wire (typically copper)
surrounded by a round outer shield conductor (which also acts as a ground for the
transmission circuit) centered on the same axis as the center conductor (hence the
name “coaxial”). The space between the center conductor and the shield is filled
with a dielectric material such as an insulating polymer or air).
• Coaxial cables are interesting as data cables because:
– They have excellent electrical bandwidth (generally on the order of a few GHz).
– Coaxial cable plants exist already in many places as television broadcast distribution networks.

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Coaxial cable
• Coaxial cables are interesting as data cables because:
– They have excellent electrical bandwidth (generally on the order of a GHz or more, depending on the cable
type and the length of the cable)
– Coaxial cable plants exist already in many places as television broadcast distribution networks.
– Coaxial cables are very simple to install and terminate.
– Coaxial networks are often very convenient for signal distribution commercial and residential buildings.
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Coaxial cable properties
• Coaxial cables used for data
applications are typically in
the 2mm – 10mm diameter
range in size, moderately
robust to bending and pulling,
during installation, and
relatively light in weight.
• Coaxial cables come in a
variety of standard
configurations to meet
specific application needs.
http://www.radio-electronics.com/info/antennas/coax/rf-coax-cable-data-types.php

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Coaxial cable speeds and range
Typical coaxial cable data speeds
• Coaxial cable systems generally have moderate to good data speeds for end users.
Future data speed increases are possible through aggregation of multiple RF
channels on the cable.
• With intermediate amplification, coaxial cables can carry signals a few kilometers.
Typical coaxial data channel

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Important coaxial characteristics
• Signal attenuation—reduces amplitude loss and physical dispersion of the signal. The
loss per meter increases with signal frequency.
• Impedance mismatches—cause reflections in the cable and internal interference in
the signal.
• What limits the speed and performance of coaxial cables?
– Cable losses—lower loss = longer transmit distances
– Impedance mismatches—better matching = less interference = faster data
– Noise and interference, especially at termination points.
– Smooth surface finish of conductors, purity and consistency of dielectric material, and careful handling of
the cables during installation—better impedance matching and lower losses = longer transmit distances
and faster data.

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Advantages of coaxial cable
• Simple to install.
• Often already in place in residences.
• Compatible with television (and other digital media)
distribution.
• Good data speed for end uses.
Coaxial data cables are
simple and practical,
especially for many
residential applications.

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Twisted-pair data cables
• Twisted pair cables are typically 4 parallel, 2-wire transmission lines, with each
transmission line twisted into a spiral geometry to help reject external
electromagnetic interference.
• The 4-pair bundle may or may not be covered by a metal screen or foil to further
reduce external interference.
• Each pair of wires may or may not be covered by a metal screen or foil to further
reduce interference from the other pairs in the cable.

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Twisted-pair cables are two-wire waveguides
• Twisted-pair cables are interesting as data cables because:
– They have very good electrical bandwidth (up to about 2 GHz, depending on the cable type and the length
of the cable).
– They are robust and flexible for use in a variety of environments.
– Twisted-pair cables are easy to install, especially for high-density terminations, short links, and in-building
applications.
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Twisted-pair speeds and ranges (Ethernet)

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Twisted-pair cable electrical standards
CAT 8 still under development, with bandwidth definition to ~2000MHz.

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Cable standards support data standards
https://www.bicsi.org/uploadedfiles/Conference_Websites/Fall_Conferences/2011/present
ations/The_40Gbps_Twisted-Pair_Ethernet_Ecosystem.pdf

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What are the capacity limits of data cables?
• From information theory, it is possible to
calculate the capacity of data cables, based
on their electrical frequency response and
the signal-to-nose ratio (Shannon’ Law)

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Twisted-pair electrical performance
• Design challenges:
– Impedance matching (better return loss)
– Lower insertion losses
– Cancellation of crosstalk (NEXT and FEXT)

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Twisted-pair cables reach theoretical capacity ~ 100Gbps.
• Given previous and current trends, twisted-pair copper cables should continue
to support data center needs until about 2025-2030.
• Thereafter, there will likely a more accelerated shift toward fiber-optic cabling,
even in over short distances, despite expected increases in cost, due to
bandwidth needs.
• Copper cables will need to be re-imagined into higher-performance designs or
slowly phased-out.
http://www.nexans.us/US/2009/DC09_paper.pdf
Theoretical capacity analysis for CAT 7A cables (2009)

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Important twisted-pair characteristics
• Signal attenuation—reduces amplitude loss and physical dispersion of the signal. The
loss per meter increases with signal frequency.
• Impedance mismatches—cause reflections in the cable and internal interference in
the signal.
• Crosstalk between nearby twisted pairs—causes interfence in the signal
• Important considerations to minimize losses and interference
– Smooth wire surface finish.
– Consistent wire spacing, consistent twist angle,
– Pure and evenly applied dielectric materials on the wires.

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Trends and drivers in data centers
• Most companies continue to expand their data center
infrastructure to support information-intensive business
needs and the need to global data
• The growth in so-called “Cloud Computing” and
outsourcing of network services is resulting in construction
of very large data centers. An emerging problem is the
ability to power and cool these massive installations.
• The information itself requires very little energy. It is the
storage, processing, and retrieval of the data that
consumes most of the energy.
• Energy consumers in the data center.
– Memory reading and writing
– Microprocessors
– Transmitters/Receivers (electric and optical)
– Modems and interfaces
• Virtually every watt of power that is used in a data center
needs to eventually be removed as heat using either
active or passive cooling.

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Energy use in data centers
--The power density of a data center is 100 times more than that of a large commercial office building
--Google alone has around 13 data centers all through out the world. And in 2014, three such facilities were added to
this list. As per the recent estimate conducted by Microsoft, Google has over 1 million servers in all its data centers
based in world. It is official now that Microsoft leads this table with 100,000 server count. Google’s data centers use
around 260 million watts of power which accounts to 0.01% of global energy. This power is enough to consistently
power 200,000 homes.
https://storageservers.wordpress.com/2013/07/17/facts-and-stats-of-worlds-largest-data-centers/
Typical data center energy use

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Twisted-pair cables in data centers and LANs
• Twisted-pair data cable continues to be a viable material for data
centers and LANs, where >99% of the connections are 100m or less
in length.
• However, copper only retains its advantage as long as it can
compete with fiber optics in terms of data speed.
• The advantages listed above are only valid if the cable can support
enough data bandwidth. Data speed is essential.
• Energy consumption in networks and data centers is an emerging
issue. Electrically efficient cabling solutions, icluding twisted pair
cables, can help insure data centers are as energy efficient as
possible.

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Twisted-pair wires remain a practical cabling solution…
• From the trends and developments in data processing and networking
speeds, copper data cables will continue to have a place for at least 10-15
years, or until about 2030 (with good installed performance for another 10
years or so).
• Copper cables represent a robust, cost-effective, and high performance
medium for connections in data centers and LANs.
• As data speeds routinely begin to exceed about 100Gbps, the use of either
fiber optics or other electrical cabling media with higher frequency
bandwidth will be required.
…for a while longer in their current form.

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Conclusion
• In core networks and other very high traffic segments in the network, optical
fiber seems to be an interesting solution.
• At aggregation points where the connection density is very high, and the links
are short twisted pair is an interesting solution.
• For residential and small business end users, coaxial cable can also be an
interesting solution.
• The design space for cabling solutions is complex, and all three cabling
formats seem to have a place for some years into the future. As networking
technology and cabling development advance, the demand will favor high
bandwidth solutions, with the condition that they are also energy efficient and
have low-life cycle costs.

34. KupferTek
High-Speed Data Cables
Low-cost, energy-efficient, high-speed data connections
for data centers and local area networks