Cisco DNCS System Release 2.7 3.7 4.2 设计指南
4000358 Rev B
Introducing DOCSIS
1-11
System Description
Introduction
This section describes the DBDS infrastructure in which DOCSIS-capable DHCTs
operate. This section also provides descriptions of the various DHCT communication
modes (DCMs) that are required to deploy DOCSIS-capable DHCTs in the DBDS. In
addition, a diagram is provided that shows the layout of a network that can support
the various communication modes.
Deploying DOCSIS-Capable DHCTs into the DBDS
There are two types of DOCSIS-capable DHCTs:
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One type is a Mixed DOCSIS/DAVIC-capable DHCT that has two out-of-band
tuners and can receive both DAVIC and DOCSIS channels simultaneously.
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The other type is a DOCSIS-only DHCT that has one out-of-band tuner and can
receive either a DAVIC or DOCSIS channel but not both simultaneously.
Some cable service operators deploying DOCSIS-capable DHCTs into existing
systems may continue to operate their DAVIC QPSK out-of-band transmitters.
Cisco’s Mixed DOCSIS/DAVIC-capable DHCTs can receive the DAVIC out-of-band
channel while simultaneously using a DOCSIS channel for interactive
communications. In this case, the out-of-band data can take the “traditional” route
over the DAVIC channel.
Other cable service providers may deploy DOCSIS-capable DHCTs into new hubs or
Other cable service providers may deploy DOCSIS-capable DHCTs into new hubs or
new systems that may not have a DAVIC QPSK infrastructure. In this case, the
system must transmit out-of-band data over the DOCSIS channel through a DSG-
compliant CMTS.
A high-level description of each DHCT communication mode is provided in DHCT
A high-level description of each DHCT communication mode is provided in DHCT
Communication Modes, next in this section.