Specifications

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Cisco Cable Modem Termination System Feature Guide
0L-1467-02
Chapter 3 Spectrum Management for the Cisco Cable Modem Termination System
Configuration Tasks
Note For more information on the cable upstream modulation-profile command, see the Cisco Broadband
Cable Command Reference Guide on Cisco.com and on the Documentation CD-ROM.
For examples of how to view modulation profile information and to define a modulation profile, see the
“Dynamic Upstream Modulation Examples” section on page 3-64.
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.
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
Configures the interface, where:
type = cable
slot = slot number in chassis (slot numbers begin with a 0)
port = port number on cable modem slot (port numbers begin
with a 0)
Step 5
Router(config-int)# cable upstream
port-number modulation-profile
primary-profile-number
secondary-profile-number
Adds the modulation profile to the interface, where:
port-number = port number on cable modem slot (port numbers
begin with a 0)
primary-profile-number = the primary modulation profile
added to the interface.
secondary-profile-number = the additional modulation profile
added to the interface.
Step 6
Router(config-int)# exit
Exits back to configuration mode.
Command Purpose