Tài liệu The Ideal Headend Evolution to Carrier Class ppt

The Ideal Headend
Evolution to Carrier Class
WHITE PAPER
Today’s successful cable operators are ramping up their
networks to deliver advanced services—HD video-on-
demand (VOD), tiered high-speed data, voice-over-IP
(VoIP) and commercial services. MSOs are focused on
improving network reliability and customer satisfaction,
and understand the importance of “carrier-class”
infrastructure. In order to reach the highest level of
delivering the extremely reliable services customers
expect, MSOs must begin thinking about the “ideal
headend.”
Path to the ideal headend
In the most basic terms, an ideal headend is the key to
enabling MSOs to grow their system without major
rebuilds each time new services are added. In the past,
these networks were typically designed and built to meet
only the needs of the day. To be successful in today’s
brutally competitive environment, the mindset has to
shift. Cable operators must look five to 10 years into the
future and design a system that can easily accept and
integrate new equipment into the existing network—a
system that can deliver voice, video, data and wireless
services for the quadruple play.
As high-tech hardware, such as VOD servers, is
introduced to the network, connectivity infrastructure
must be designed to “wrap” the new equipment.
Keeping in mind the old cliché that a network is only as
strong as its weakest link, proper network
documentation, a solid foundation of RF and fiber signal

management, and power distribution solutions must
work hand-in-hand to make network reconfigurations
faster, easier to perform and far less risky to implement.
This flexibility and reliability is only achieved by building
the headend of the future. One path is to use modular
components that enable operators to easily expand their
systems to offer the best performance. The high density
of these system components also requires a much smaller
footprint within the facility.
Let’s take a look at some of the criteria for designing and
building an ideal cable headend—power distribution,
circuit-switched telephony, fiber-to-the-premise (FTTP)
support and fiber cable management, data-center
connectivity solutions, digital signal cross-connects and
RF signal management.
Power distribution
Building a future-proof headend begins with ensuring
you have the necessary power distribution facilities in
place to support new equipment and services.
The type of power required will be determined by
the services to be delivered across the system.
However, MSOs planning to deliver telephony services
over IP (which include lifeline or E-911 services) will have
to change their power structure.
Traditionally, most of the equipment found in an MSO’s
headend was operated by AC power. However, AC
power is not built to handle telephony services because it
cannot easily provide continuous, uninterrupted power.
Therefore, in the ideal headend, cable operators should
be looking at incorporating some type of DC power

configuration with battery back-up.
Today, most cable headends use some type of hybrid
power—some equipment powered by AC and some
by DC. But telephone companies are almost exclusively
DC powered, so for cable operators to emulate the
carrier-class services of their telecom competitors, they
will need to adapt their power distribution to enable
delivery of additional services. DC power and redundancy
will become critical issues. For instance, the systems that
power the high-speed Internet are extremely power
hungry, drawing up to 70 amps per unit, and there are
very specific requirements for continuously powering
these devices.
Although DC requires more initial cost during installation
and uses more real estate, the improvement to network
reliability cannot be overstated. Capital expenditures
must be weighed against the possibility of higher
operational costs down the road. Truck rolls and
technicians are a large part of operational costs so,
simply put, upping the reliability lowers the number of
service calls required.
Cable MSOs ideal headend—the evolution to ‘carrier class’
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THE CABLE MSO’S IDEAL HEADEND—THE EVOLUTION TO ‘CARRIER-CLASS’
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There are other good reasons for converting headends to
DC power despite the conversion costs. Future services,
including VoIP, VOD and IPTV, will up the ante in terms
of a provider’s ability to quickly add, turn up and reliably
maintain whatever service bundle each customer
chooses. Problems relating to power in the new FTTP

networks that offer “full suite” services will simply be
unacceptable.
The impact of DC power is immediately apparent if one
considers several attributes:
• DC power is conditioned power, enabling equipment
to run more smoothly and efficiently
• Systems can be configured for longer standby at
hubs or nodes
• Since equipment is direct-wired rather than plugged
in, connections are unlikely to disconnect
• Each piece of equipment can now be
individually fused
• There is A to B power redundancy to each individual
piece of equipment
• A DC power plant is easier to monitor
• Cable management, a huge consideration in FTTP
networks, is more cleanly managed
Power is never a no-brainer, especially when it comes to
doing the “heavy lifting” for the network. If the power
fails, the network fails. If the network fails, customers
look elsewhere for more reliable service. In the ideal
headend, the right power scheme is employed to offer
uninterruptible delivery of advanced IP services.
Circuit-switched telephony
In typical cable system, circuit-switched telephony is
accomplished by headend equipment that “talks” to a
telephone switch at a telephone company’s central office.
However, with the advent of IP telephony, those systems
are rapidly migrating to some form of packetized
transport. Telephony is exiting the days of circuit switching

and entering the new world of packetized switching.
With that in mind, an ideal headend will need to operate
both systems simultaneously for a period of time,
realizing that at some point the circuit-switched solution
will disappear. This hybrid operation of two systems will
be necessary as packet switching gradually evolves to
become the dominant telephony system.
Throughout this evolution, cable operators must also
have the ability to reconfigure their circuit-switched
customers to the new packet-switched operation.
Customer migration onto a packet-switched system must
be completely transparent.
Supporting FTTP
New FTTP technologies are also requiring MSOs to ensure
their networks provide a means to upgrade and expand
to meet any future demands. Although MSOs already
have high bandwidth hybrid fiber/coax (HFC)
architectures in place and are capable of delivering
bandwidth-hungry services to residential and small
business customers, they still must look to the future.
Their core infrastructure must be flexible and scalable
enough to allow them to compete with the massive
amounts of fiber being driven deeper into the access.
An ideal headend will enable MSOs to realize the full
benefits of the broadband systems they already have in
place, while allowing them the ability to deliver next-
generation services like VOD, HSD, and VoIP that are
carrier grade.
Cable MSOs ideal headend—the evolution to ‘carrier class’
Page 3

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ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101
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Fiber cable management
The ideal headend will be designed not only to
enable cable operators the flexibility to add new
subscribers, but also easily reconfigure the
network to adapt to customer churn. The
principles of a good fiber management system
that apply to telecom service providers are
equally as important to cable MSOs.
Fiber cable management is broken down into a
few key principles, the first of which is to develop
clear routing paths that are obvious to any
technician at a glance. In other words, routing the
fiber correctly should be intuitive and easily
accomplished.
Next, fiber cable should be physically protected
to prevent damage as a result of technicians
working on other parts of the rack, cabinet or

cable-management device. Measures should be
taken to avoid damaging, pulling, stretching,
crushing or pinching existing fibers in the vicinity
of the work area.
Another key is bend-radius protection. As fiber is
bent, the radius can become too small and allows
light to escape the core and enter the cladding.
The result is insertion loss in the fiber or a
macrobend that decreases the signal or, in
extreme cases, causes complete signal loss and
data-transfer failures.
Finally, an integrated slack-storage strategy or
system is necessary. Each fiber, due to the high
tolerance needed, is normally terminated in the
factory to eliminate the high costs involved with
field terminations. This typically results in fixed
cable lengths and patch cords. Once the
technician arrives at the job site to make a
connection, the fiber cable or patch cord may be
longer than what is actually required.
Therefore, a system must allow the proper storage
of the slack—the difference in length between
what is actually needed to physically make the
connection and what the technician actually has
to work with.
Data center connectivity
Historically, cable providers only had a handful of
data cables in the headend, mostly connecting
computers to the network. But today, data is a
large part of the headend, especially to provide

high-speed Internet services. Because of the
increased demand for high-speed data, cable
management solutions must be incorporated for
structured cabling solutions. Offering data-based
services requires the cable operator to transport
traffic from the Internet service provider (ISP) to
each server and onto the cable modem transport
system (CMTS) to customers.
As with other areas of the ideal headend, the
data-center portion of the network must be
completely flexible and scalable. In fact, data
delivery has become so important to today’s
MSOs, the ideal headend is beginning to transition
from just housing RF signal-management
equipment into resembling an actual data center.
Unlike telecom providers who are scrambling to
get fiber capacity to the home, MSOs already have
the large pipe they need. Their focus now should
be on ensuring they have the proper equipment in
the headend to deliver those services.
Conclusion
Just as telecom providers must adapt their
networks to deliver services like IPTV, MSOs have
to take steps to ensure they can deliver the data
and telephony services as a bundled offering to
customers. Delivering video has always been the
“bread & butter” for the MSO, but gearing up
cable systems to deliver data and voice greatly
lowers the tolerance for error in the system.
Building the ideal headend that is flexible, scalable,

and reliable for delivering triple-play bundles will
enable the delivery of carrier-class services that
customers expect and demand. ADC’s time-tested
products and professional services help enable
cable operators to design and build the reliable and
flexible multivendor headends, and provide firm
footing on which to compete in the triple- and
quadruple-play services space.