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Implementing Secure

Converged Wide AreaNetworks (ISCW)

Module 2: Teleworker Connectivity

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Module 2:

TeleworkerConnectivity

Lesson 2.2: Describing Cable Technology

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Objectives

Describe the components of a typical cable system.

Identify the benefits of a cable system.

Explain how cable uses a part of RF electromagneticfrequencies to transmit.

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What is a Cable System?

CATV originally meant community antenna television. This formof transmission shared TV signals.

Cable systems were originally built to extend the reach of TVsignals and improve over-the-air TV reception.

Modern cable systems use fiber and coaxial cable for signaltransmission.

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Cable Technology Terms

Broadband

CATV

Coaxial cable

Tap

Amplifier

HFC

Downstream

Upstream

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Cable System Components

Subscriber Drops

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Cable System Benefits

Cable is cost-effective because broadcast architecture

is cascaded to users.

Cable supports different services:

Analog video

Digital video

Voice

Data

Inexpensive high-speed Internet access enables the

application of advanced SOHO and teleworkerdeployments.

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Digital Signals over Radio Waves

Cable uses a part of RF electromagnetic frequencies.

Cable can transmit signals simultaneously in either direction.

RF portion used is subdivided for the two paths:

Downstream: Headend-to-subscriber has 810 MHz of RF bandwidth.

Upstream: Subscriber-to-headend has 37 MHz of RF bandwidth.

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DOCSIS

DOCSIS is a standard for certification of cable

equipment vendor devices (cable modem and cablemodem termination system).

DOCSIS specifies the physical and MAC layers.

DOCSIS defines RF interface requirements for a data-over-cable system.

Cable equipment vendors must pass certificationconducted by CableLabs.

Euro-DOCSIS is a variation adapted for use in Europe.

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Summary

Modern cable systems provide two-way communication

between subscribers and the cable operator. Cableoperators now offer customers advancedtelecommunications services including high-speedInternet access, digital cable television, and residential

telephone service. Cable systems support telephony and data services

and analog and digital video services.

DOCSIS defines the communications and operation

support interface requirements for a data-over-cablesystem and permits the addition of high-speed datatransfer to an existing CATV system.

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Q and A

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Resources

DOCSIS

http://www.cablemodem.com/specifications

Broadband Cable

http://www.cisco.com/en/US/customer/tech/tk86/tsd_technology_support_category_home.html

CableLabs

http://www.cablelabs.com/

http://www.cablemodem.com/specificationshttp://www.cisco.com/en/US/customer/tech/tk86/tsd_technology_support_category_home.htmlhttp://www.cisco.com/en/US/customer/tech/tk86/tsd_technology_support_category_home.htmlhttp://www.cablelabs.com/http://www.cablelabs.com/http://www.cisco.com/en/US/customer/tech/tk86/tsd_technology_support_category_home.htmlhttp://www.cisco.com/en/US/customer/tech/tk86/tsd_technology_support_category_home.htmlhttp://www.cablemodem.com/specifications

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