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Benefits

Cisco uBR7246 Universal Broadband Router Feature Enhancements 3

Headend—Central distribution point for a CATV system. Video signals are received here from

satellite (either co-located or remote), and the frequency is converted to the appropriate channels.

Channels are then combined with locally originated signals, and rebroadcast onto the hybrid

ﬁber-coaxial (HFC) plant. For a CATV data system, the headend is the typical place to link the HFC

system and any external data networks.

HFC—Hybrid ﬁber-coaxial. Older CATV systems were provisioned using only coaxial cable.

Modern systems use ﬁber transport from the headend to an optical node located in the neighborhood

to reduce system noise. Coaxial cable runs from the node to the subscriber. The ﬁber plant is

generally a star conﬁguration with all optical node ﬁbers terminating at a headend. The coaxial cable

part of the system is generally a trunk and branch conﬁguration.

Homes Passed—Number of homes or ofﬁces potentially serviceable by a cable system either on a

per node or per system basis.

Midsplit—A frequency allocation plan where 5 to 108 MHz is used for upstream data and 178+

MHz is used for downstream data.

Optical Node—A device used to convert broadband RF (for example, television signals) to and from

a ﬁber optic signal. An optical node is typically located in the outside ﬁeld.

Predator—Code name for the Cisco 7200 class of modular routers that accept PCI bus-based port

adapters.

QAM—Modulation scheme mostly used in the downstream direction (QAM-64, QAM-256).

QAM-16 is expected to be usable in the upstream direction. Numbers indicate number of code points

per symbol. Number of bits per symbol can be computed by 2

(number of bits/symbol)

= number of code

points.

QPSK—Modulation scheme used in the upstream direction. Supports two data bits per symbol.

Spectrum Group—A combiner group can be associated with a frequency hop table. This frequency

hop table associated with a combiner group is the spectrum group, as opposed to the RF topology

point, which is the combiner group. See also Combiner Group.

Subsplit—A frequency allocation plan where 0 to 42 MHz is used for upstream data and 50+ MHz

is used for downstream data.

Tap—A passive device that divides the signal between the trunk or feeder lines and splits the signal

into ports for subscriber drop access.

Telephony Return—A variant of a cable data system where the return path from the subscriber

cable modem is routed over a dialup (or ISDN) connection instead of over an upstream channel.

Trunk Line—A CATV backbone coaxial cable. This runs from an Optical Node and through a

speciﬁc neighborhood or serving area.

Upstream—The set of frequencies used to send data from a subscriber to the headend.

Conﬁguration Tasks

The basic conﬁguration tasks required by this version of the Cisco uBR7246 cable router are the

same as those described in the Cisco uBR7246 Universal Broadband Router Installation and

Conﬁguration Guide and the Voice, Video, and Home Applications Conﬁguration Guide.

Additional conﬁguration tasks are:

• Conﬁguring Spectrum Groups (Optional)

• Conﬁguring Frequency Hopping (Optional)

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