DOCSIS 1.0
and 1.1 Mixed Mode:
cable
modulation-profile
profile
{ mix | qam-16 | qpsk | robust-mix }
no
cable
modulation-profile
profile
{ iuc | mix | qam-16 | qpsk | robust-mix }
cable
modulation-profile
profile
iuc
fec-tbytes
fec-len
burst-len
guard-t
mod
scrambler
seed
diff
pre-len
last-cw
uw-len
DOCSIS
1.x/2.0 Mixed Mode:
cable
modulation-profile
profile
{ mix-high | mix-low | mix-mid | mix-qam | qam-16 | qpsk | robust-mix-high | robust-mix-mid | robust-mix-qam }
no
cable
modulation-profile
profile
{ iuc | mix-high | mix-low | mix-mid | mix-qam | qam-16 | qpsk | robust-mix-high | robust-mix-mid | robust-mix-qam }
cable
modulation-profile
profile
iuc
fec-tbytes
fec-len
burst-len
guard-t
mod
scrambler
seed
diff
pre-len
last-cw
uw-len
DOCSIS 2.0
A-TDMA Mode:
cable
modulation-profile
profile
{ mix-high | mix-low | mix-mid | mix-qam | qam-8 | qam-16 | qam-32 | qam-64 | qpsk | robust-mix-high | robust-mix-low | robust-mix-mid }
no
cable
modulation-profile
profile
{ iuc | mix-high | mix-low | mix-mid | mix-qam | qam-8 | qam-16 | qam-32 | qam-64 | qpsk | robust-mix-high | robust-mix-low | robust-mix-mid }
cable
modulation-profile
profile
iuc
fec-tbytes
fec-len
burst-len
guard-t
mod
scrambler
seed
diff
pre-len
last-cw
uw-len
Cisco IOS
Release 12.2(33)SCC and Later
DOCSIS 2.0
A-TDMA Mode and DOCSIS 2.0 S-CDMA Mode:
cable
modulation-profile
profile
{ mix-high | mix-low | mix-mid | mix-qam | qam-16 | qpsk | robust-mix-high | robust-mix-low | robust-mix-mid }
no
cable
modulation-profile
profile
{ iuc | mix-high | mix-low | mix-mid | mix-qam | qam-16 | qpsk | robust-mix-high | robust-mix-low | robust-mix-mid }
cable
modulation-profile
profile
iuc
fec-tbytes
fec-len
burst-len
guard-t
mod
scrambler
seed
diff
pre-len
last-cw
uw-len
Cisco cBR Series Converged Broadband Routers
DOCSIS 1.x
TDMA Mode:
cable
modulation-profile
profile
tdma
{ mix | qam-16 | qpsk | robust-mix }
no
cable
modulation-profile
profile
tdma
{ iuc | mix | qam-16 | qpsk | robust-mix }
cable
modulation-profile
profile
tdma
iuc
fec-tbytes
fec-len
burst-len
guard-t
mod
scrambler
seed
diff
pre-len
last-cw
uw-len
DOCSIS
1.x/2.0 TDMA-ATDMA Mixed Mode:
cable
modulation-profile
profile
mixed
{ mix-high | mix-low | mix-mid | mix-qam | qam-16 | qpsk | robust-mix-high | robust-mix-mid | robust-mix-qam }
no
cable
modulation-profile
profile
mixed
{ iuc | mix-high | mix-low | mix-mid | mix-qam | qam-16 | qpsk | robust-mix-high | robust-mix-mid | robust-mix-qam }
cable
modulation-profile
profile
mixed
iuc
fec-tbytes
fec-len
burst-len
guard-t
mod
scrambler
seed
diff
pre-len
last-cw
uw-len
DOCSIS 2.0
A-TDMA Mode:
cable
modulation-profile
profile
atdma
{ mix-high | mix-low | mix-mid | mix-qam | qam-8 | qam-16 | qam-32 | qam-64 | qpsk | robust-mix-high | robust-mix-low | robust-mix-mid }
no
cable
modulation-profile
profile
atdma
{ iuc | mix-high | mix-low | mix-mid | mix-qam | qam-8 | qam-16 | qam-32 | qam-64 | qpsk | robust-mix-high | robust-mix-low | robust-mix-mid }
cable
modulation-profile
profile
atdma
iuc
fec-tbytes
fec-len
burst-len
guard-t
mod
scrambler
seed
diff
pre-len
last-cw
uw-len
Usage Guidelines
A modulation
profile is a collection of at least six burst profiles that are sent out in an
upstream channel descriptor (UCD) message to configure a modem’s transmit
parameters.
You can use the
no
cable
modulation-profile command to remove all
modulation profiles except the default modulation profiles (1, 21, 41, 101,
121, 201, 221, 241, and 321, depending on the cable interface line cards being
used). In the case of the default modulation profiles, the
no
cable
modulation-profile command resets the default
profile to its default values.
We recommend
that you use the predefined profiles instead of manually specifying the
individual bursts for a modulation profile. The predefined profiles are
optimized for the default of 32 symbols per minislot for each particular
modulation scheme. The
robust
predefined profiles use a longer preamble for better handling of noise on the
upstream, but at the cost of consuming more PHY layer bandwidth than the other
non-robust profiles.
If you want to
manually specify the individual bursts, enter a line with all parameters for
each upstream burst type. Then repeat this command for each burst type, which
also must be fully specified. A profile with incomplete or missing bursts can
cause unreliable operation or loss of modem connectivity.
Caution |
Changes to
modulation profiles causes changes to the physical layer. Because changing
physical layer characteristics affects router performance and function, this
task should be reserved for expert users who have a thorough understanding of
DOCSIS systems and how each parameter affects the network.
|
Note |
The
reqdata
burst type is included as a placeholder for SNMP scripts that might reference
it, but it has no effect. You can use this command (and SNMP commands) to
specify the
reqdata
types, but the DOCSIS MAC scheduler on the Cisco CMTS does not
use this type of burst.
|
From Cisco IOS
Release 12.2(33)SCC and Cisco IOS-XE Release 3.15.0S onwards, the
qam-8,
qam-32, and
qam-64
modulation profiles are available in hidden and internal modes only. When you
are using the
initial and
station
bursts for DOCSIS 2.0 A-TDMA mode,
qam-8,
qam-32, and
qam-64
modulation profiles are available in hidden mode only. However, these
modulation profiles are available for
a-long,
a-short,
a-ugs,
long,
request,
reqdata,
and
short.
Modulation Profile
Ranges
The valid range
for modulation profiles depends on the cable interface being used and the type
of modulation profile being created. The table below lists the valid ranges
according to cable interface and modulation type.
Table 1 Allowable
Ranges for Modulation Profiles
Cable
Interface
|
DOCSIS
1.X (TDMA)
|
Mixed
DOCSIS 1.X/2.0
|
DOCSIS
2.0 (A-TDMA)
|
DOCSIS
2.0 (S-CDMA)
|
Cisco
uBR7100 series
|
1 to
101, default=1
|
N/A
|
N/A
|
N/A
|
Cisco
uBR-MC16C
|
1 to
10, default=1
|
N/A
|
N/A
|
N/A
|
Cisco
uBR-MC16S
|
1 to
10, default=1
|
N/A
|
N/A
|
N/A
|
Cisco
uBR-MC28C
|
1 to
10, default=1
|
N/A
|
N/A
|
N/A
|
Cisco
uBR-MC5X20S, Cisco uBR-MC5X20U, Cisco uBR-MC5X20H
|
21 to
30, default=21
|
121 to
130, default=121
|
221 to
230, default=221
|
321 to
330 (default is 321)
|
Cisco
uBR-MC16U/X, Cisco uBR-MC28U/X
|
41 to
50, default=41
|
141 to
150, default=141
|
241 to
250, default=241
|
N/A
|
Cisco
cBR-8 CCAP
|
1 to
400, default=21
|
1 to
400, default=121
|
1 to
400, default=221
|
N/A
|
1 Only 8 modulation
profiles are supported in Cisco IOS software releases before 12.2(15)BC1, so in
these releases the valid range is from 1 to 8.
DOCSIS 1.0 and DOCSIS
1.1 Support
For DOCSIS 1.0
and 1.1 cable modems, the following burst types are required: request, request
data, initial maintenance, station maintenance, short grant, and long grant.
You must issue the
cable
modulation-profile command six times for each
individual burst type to correctly create a new modulation profile.
The three
default profiles can be used to quickly create modulation profiles, without
having to specify the parameters for each individual burst:
mix,
qpsk, and
qam-16. The
burst parameters for the request, initial, station maintenance, short, and long
bursts are set to their default values for each burst type. (The
reqdata
burst type is not created when using the default modulation profiles because it
is not used by the MAC scheduler.)
The default
profiles allow basic profiles to be implemented for initial network
connectivity. As the characteristics of a cable plant become better known, the
profiles can then be adjusted accordingly.
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
qpsk or
mix
modulation profile for the primary profile.
|
Caution |
Turning the
scrambler off can cause packet loss and is used only in lab testing
environments.
|
Errors or
incompatible configurations in the burst profiles cause cable modems to drop
connectivity, to drop short or long data packets, or to fail to connect to the
network. It is possible to build a burst profile set for which no
implementation of a DOCSIS receiver is capable of receiving the modem’s
transmission.
Data rates of
160 Ksymbol/sec and 2560 Ksymbol/sec are highly sensitive to unique word
length, preamble length, and FEC sizing. Incorrect choices for these values can
cause poor, or no, connectivity at these symbol rates.
DOCSIS 2.0 Support
Cisco IOS
Release 12.2(11)CY, 12.2(15)BC1, 12.3BC, 12.2(33)SCA, 12.2(33)SCC, and later
releases support 10 modulation profiles for each of the three DOCSIS modes
(DOCSIS 1.X, DOCSIS 2.0, and mixed mode) on the Cisco uBR10012 and Cisco
uBR7200 series routers, for a total maximum of 30 modulation profiles. In
addition, the router also creates several default modulation profiles (1, 21,
41, 101, 121, 141, 201, 221, 241, and 321, depending on the cable interface
line cards that are installed).
Examples
The following
example shows how to create a mixed modulation profile, using 16-QAM for the
short and long grant bursts and QPSK for the request, initial ranging, and
station maintenance bursts on a Cisco uBR10012 router. The burst parameters are
set to their default values for each burst type.
Router(config)# cable modulation-profile 8 mix
Router(config)# exit
Router# show cable modulation-profile 8
Mod IUC Type Preamb Diff FEC FEC Scrambl Max Guard Last Scrambl Preamb
length enco T CW seed B time CW offset
BYTES size size size short
8 request qpsk 64 no 0x0 0x10 0x152 0 8 no yes 0
8 initial qpsk 128 no 0x5 0x22 0x152 0 48 no yes 0
8 station qpsk 128 no 0x5 0x22 0x152 0 48 no yes 0
8 short qam 144 no 0x6 0x4B 0x152 6 8 yes yes 0
8 long qam 160 no 0x8 0xDC 0x152 0 8 yes yes 0
Router#
Note |
The above
example shows the default values for the burst parameters. The main differences
in the default values between 16-QAM and QPSK bursts are in the Type and
Preamble Length fields.
|
The following
example shows how to define the burst parameters for profile 2 with the
following parameters: 0 fec-tbytes, 16 kbytes fec-len, a burst-len of 1, a
guard time of 8, a mod value of
qpsk,
scrambler enabled with a seed value of 152, differential encoding disabled, a
preamble length of 64 bits, a fixed code-word length, and 8-bit unique words
for upstream unique word length a Cisco uBR10012 router.
Router(config)# cable modulation-profile 2 request 0 16 1 8 qpsk scrambler 152 no-diff 64 fixed uw8
Router(config)# cable modulation-profile 2 reqdata 0 16 1 8 qpsk scrambler 152 no-diff 64 fixed uw8
Router(config)# cable modulation-profile 2 initial 5 34 0 48 qpsk scrambler 152 no-diff 128 fixed uw16
Router(config)# cable modulation-profile 2 station 5 34 0 48 qpsk scrambler 152 no-diff 128 fixed uw16
Router(config)# cable modulation-profile 2 short 6 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8
Router(config)# cable modulation-profile 2 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8
Note |
You must
create all of the bursts (request, initial, station, short and long) for this
modulation profile, using the
cable
modulation-profile command. The
reqdata
burst is optional.
|
The following
example shows an example of a DOCSIS 1.X/DOCSIS 2.0 mixed modulation profile a
Cisco uBR10012 router:
Router# configure terminal
Router(config)# cable modulation-profile 142 request 0 16 0 8 qpsk scrambler 152 no-diff 64 fixed uw8
Router(config)# cable modulation-profile 142 initial 5 34 0 48 qpsk scrambler 152 no-diff 32 fixed uw16
Router(config)# cable modulation-profile 142 station 5 34 0 48 qpsk scrambler 152 no-diff 32 fixed uw16
Router(config)# cable modulation-profile 142 short 5 75 6 8 qpsk scrambler 152 no-diff 72 shortened uw8
Router(config)# cable modulation-profile 142 long 8 220 0 8 qpsk scrambler 152 no-diff 80 shortened uw8
Router(config)# cable modulation-profile 142 a-short qpsk0 0 18 5 99 10 8 64qam scrambler 152 no-diff 128 shortened uw8
Router(config)# cable modulation-profile 142 a-long qpsk0 0 18 15 200 0 8 64qam scrambler 152 no-diff 128 shortened uw8
Router(config)#
The following
example shows an example of a DOCSIS 2.0 A-TDMA modulation profile a Cisco
uBR10012 router:
Router# configure terminal
Router(config)# cable modulation-profile 242 request qpsk0 0 0 0 16 0 8 qpsk scrambler 152 no-diff 64 fixed uw8
Router(config)# cable modulation-profile 242 initial qpsk0 0 0 5 34 0 48 qpsk scrambler 152 no-diff 32 fixed uw16
Router(config)# cable modulation-profile 242 station qpsk0 0 0 5 34 0 48 qpsk scrambler 152 no-diff 32 fixed uw16
Router(config)# cable modulation-profile 242 short qpsk0 0 0 5 75 6 8 qpsk scrambler 152 no-diff 72 shortened uw8
Router(config)# cable modulation-profile 242 long qpsk0 0 0 8 220 0 8 qpsk scrambler 152 no-diff 80 shortened uw8
Router(config)# cable modulation-profile 242 a-short qpsk0 0 18 5 99 10 8 64qam scrambler 152 no-diff 128 shortened uw8
Router(config)# cable modulation-profile 242 a-long qpsk0 0 18 15 200 0 8 64qam scrambler 152 no-diff 128 shortened uw8
Router(config)#
The following
example shows an example of a DOCSIS 2.0 S-CDMA modulation profile:
Router# configure terminal
Router(config)# cable modulation-profile 324 request 0 16 10 16qam scrambler 152 no-diff 64 fixed qpsk0 spreader 12 12 no-tcm
Router(config)# cable modulation-profile 324 initial 0 16 10 16qam scrambler 152 no-diff 64 fixed qpsk0 off-spreader 12 12 no-tcm
Router(config)# cable modulation-profile 324 station 0 16 10 16qam scrambler 152 no-diff 64 fixed qpsk0 off-spreader 12 12 no-tcm
Router(config)# cable modulation-profile 324 a-short 0 16 10 16qam scrambler 152 no-diff 64 fixed qpsk0 off-spreader 12 12 no-tcm
Router(config)# cable modulation-profile 324 a-long 16 10 16qam scrambler 152 no-diff 64 fixed qpsk0 off-spreader 12 12 no-tcm
Router(config)# cable modulation-profile 324 a-ugs 16 10 16qam scrambler 152 no-diff 64 fixed qpsk0 off-spreader 12 12 no-tcm
Router(config)#
The following
example shows how to create TDMA modulation profiles on a
Cisco cBR series router:
Router# configure terminal
Router(config)# cable modulation-profile 24 tdma qam-16
Router(config)# cable modulation-profile 25 tdma qpsk
Router(config)# cable modulation-profile 26 tdma request 0 16 0 8 qpsk scrambler 152 no-diff 68 fixed
The following
example shows how to create TDMA/A-TDMA mixed modulation profiles on a
Cisco cBR series router:
Router# configure terminal
Router(config)# cable modulation-profile 125 mixed qam-16
Router(config)# cable modulation-profile 127 mixed request 0 16 0 8 qpsk scrambler 152 no-diff 68 fixed
Router(config)# cable modulation-profile 127 mixed initial 5 34 0 48 qpsk scrambler 152 no-diff 128 fixed
The following
example shows how to create A-TDMA mixed modulation profiles on a
Cisco cBR series router:
Router# configure terminal
Router(config)# cable modulation-profile 225 atdma qam-64
Router(config)# cable modulation-profile 227 atdma request 0 16 0 8 qpsk scrambler 152 no-diff 68 fixed qpsk0 1 2048
Router(config)# cable modulation-profile 227 atdma initial 0 16 0 0 qpsk no-scrambler no-diff 2 fixed qpsk1 0 18
See the
show
cable
modulation-profile command for a description of
the output display fields.