Specifications

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Cisco Cable Modem Termination System Feature Guide
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Chapter 3 Spectrum Management for the Cisco Cable Modem Termination System
Configuration Tasks
Configuring Dynamic Upstream Modulation
To enable the Dynamic Upstream Modulation feature for the Cisco uBR-MC16S cable interface line
card, create at least two modulation profiles then assign them to the appropriate upstream.
Command Purpose
Step 1
Router(config)# configure terminal
Enters configuration mode.
Step 2
Router(config)# cable modulation-profile
profile [ mix | qam-16 | qpsk ]
Creates a modulation profile. A modulation profile is a
collection of six burst profiles sent out in a UCD message to
configure modem transmit parameters for the upstream
message types: request, reqdata, initial maintenance, station
maintenance, short grant, and long grant.
profile = Modulation profile number (1–8).
mix = Creates a default QPSK/QAM-16 mix modulation profile
(short and long grant bursts are sent using QAM-16, while
request, initial ranging, and station maintenance bursts are sent
using QPSK).
qam-16 = Creates a default QAM-16 modulation profile, where
all bursts are sent using QAM-16.
qpsk = Creates a default QPSK modulation profile, where all
bursts are sent using QPSK.
Note Do not use the QAM-16 mode unless you have verified
that your cable plant can support that modulation
profile. Most cable plants should instead use the mix
modulation profile for the primary profile.
Step 3
Router(config)# cable modulation-profile
profile [ mix | qam-16 | qpsk ]
Repeat this command to create the secondary profile. Typically,
the secondary profile is either mix or qpsk.
Note The cable modulation-profile command also supports setting the individual parameters for the initial, long
grant, request/data, request, short grant, and station ranging bursts. These parameters, however, should not
be modified unless you are thoroughly familiar with how changing each parameter affects the DOCSIS
MAC layer. Cisco recommends using the mix, qam-16, and qpsk default modulation profiles for most cable
plants.
Step 4
Router(config)# interface type slot/port
Enters interface configuration mode for the cable interface
where:
type = cable
slot = slot number in chassis for the Cisco uBR-MC16S line
card (slot numbers begin with a 0)
port = port number on cable modem slot (port numbers begin
with a 0)