Cisco uBR7200 Series MC16S Cable Modem Card

Cisco uBR7200 Series MC16S Cable
Modem Card Spectrum Management
Spectrum Management Overview
The following sections describe spectrum management implementation using Cisco uBR7200 series
software and the Cisco MC16S cable modem card.
The Cisco uBR7200 series supports the creation of up to 32 cable spectrum groups, allowing
multiple upstream ports in a single spectrum group, and specifications of configured channel widths
for upstream segments. Upstream frequencies can be assigned as follows:
•
•
Fixed.
•
Multiple subbands—the data carrier can remain in a particular subband for a duration of time and
then hop to another subband based on the defined upstream parameters.
Single subband—the CMTS administrator can define a center frequency and symbol rate such
that the boundaries of the upstream carrier stay within the subband. The frequency and symbol
rate can change within the boundary in response to noisy line conditions, based on the defined
upstream parameters.
Note The above frequency agility specifications are based on predetermined sets of frequencies
which may or may not have adequate carrier-to-noise (C/N) ratio at any given time.
•
Dynamically assigned based on a CMTS administrator-specified threshold percentage of
disconnected cable modems that must be met before a frequency hop will occur—the
Cisco uBR7200 series software can initiate a frequency hop to a clean upstream channel based
on upstream spectrum data collected by the MC16S’s spectrum management daughter card.
For more information regarding the MC16S cable modem card and its frequency hopping
capabilities, refer to the “MC16S Cable Modem Card” section on page 12.
Caution Upstream modulation profiles can be assigned to specific upstream ports based on the
Cisco cable modem card used. Only those familiar with DOCSIS who have received the proper
training should create upstream modulation profiles.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 1
Spectrum Management Overview
Two-Way Cable
The Cisco uBR7200 series universal broadband routers divide a cable network into downstream and
upstream segments. Each upstream segment typically serves one or more fiber nodes. Upstream
segments can be defined as:
•
•
Sparse segment—Containing one upstream channel per upstream segment.
Dense segment—Containing multiple upstream channels per upstream segment; frequencies
must be different.
Note A cable modem card supports either sparse or dense segments—not both.
Defining sparse segments allows the cable operator to share upstream bandwidth among fiber nodes
with fewer subscribers. Defining dense segments allows the cable operator to provide larger
upstream bandwidth to fiber nodes with lots of subscribers. Figure 1 illustrates sparse versus dense
segments.
Figure 1
Sparse Versus Dense Segment
Sparse
Segment
3
Segment
4
Segment
1
DS
US0
US1
US2
US3
Segment
2
1x4 CM card
Segment
x
attenuator
x
attenuator
Segment
6
1x4 CM card
Optical
receiver
=
Segment
5
DS
US0
US1
US2
US3
27979
Dense
Fiber-optic
cable
Cable
modems
Reverse optical
transmitter
Distribution
network
As shown in Figure 1, the downstream segment can contain multiple upstream segments. Two fiber
nodes can be in one downstream segment, but in different upstream segments.
An upstream frequency has an associated upstream input power level in dBmV. Cable operators must
make noise measurements and determine the cable plant’s spectrum management policy. Different
modulation schemes and symbol rates can be used based on the characteristics of the cable plant and
the cable modem card contained in the chassis. Bits are encoded into a two-dimensional mapping
called a constellation. Good carrier-to-noise ratio is needed to properly decode symbols into bits.
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12.0(7)XR2
Two-Way Cable
Upstream Signals
The upstream channel is characterized by many cable modems transmitting to the CMTS. These
signals operate in a burst mode of transmission. Time in the upstream channel is slotted. The CMTS
provides time slots and controls the usage for each upstream interval.
The Cisco uBR7200 series equipment periodically broadcasts Upstream Channel Descriptor (UCD)
messages to all cable modems. These messages define upstream channel characteristics including
the upstream frequencies, symbol rates and modulation schemes, Forward Error Correction (FEC)
parameters, and other physical layer values.
Cisco supports all DOCSIS error correction encoding and modulation types and formats. Upstream
signals are demodulated using Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude
Modulation (QAM). QPSK carries information in the phase of the signal carrier, whereas QAM uses
both phase and amplitude to carry information.
Sending data reliably in the upstream direction is an issue. Because upstream spectrum varies greatly
between cable plants, select upstream parameters based on your cable plant’s return paths. Select or
customize upstream profiles for maximum trade-offs between bandwidth efficiency and upstream
channel robustness. For example, 16 QAM requires approximately 7 dB higher C/N ratio to achieve
the same bit error rate (BER) as QPSK, but it transfers information at twice the rate of QPSK.
Combiner Groups
The return path of several fiber nodes can be combined together at a single point to form a single RF
frequency domain called a combiner group. The Cisco uBR7200 series universal broadband router
software allows a frequency hop table to be associated with a combiner group, called a spectrum
group.
Note A combiner group refers to an RF topology point. A spectrum group refers to the frequency
hop table associated with a combiner group.
The Cisco uBR7200 series universal broadband routers support up to 32 spectrum groups. Each
spectrum group defines the table of frequencies to be used in a specific frequency plan. Cisco
cable modem cards interface the downstream and upstream ports to the cable plant.
Frequency Allocation Table
The Cisco uBR7200 series universal broadband router software includes Cisco IOS commands that
can be used to define upstream frequency hop tables. In the global and interface configuration
modes, these are grouped under the cable spectrum-group command hierarchy.
The steps to configure a spectrum group are as follows:
•
•
•
Determine the upstream ports assigned to a combiner group.
Create the frequency hop table under Cisco IOS global configuration.
Assign the upstream port to the frequency hop table under Cisco IOS interface configuration.
Note For more information, refer to “Benefits” section on page 13.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 3
Spectrum Management Overview
Frequency Management Policy
Due to the nature of CATV technology, upstream noise management is a significant issue. Cisco
recommends that you follow rigorous North American plant maintenance procedures documented
in the NCTA Supplement on Upstream Transport Issues to adjust return amplifiers and lasers.
Cisco also recommends that system administrators configure upstream frequency hopping as a
countermeasure to long-term, narrowband noise. Cisco IOS Release 12.0(5)T1 or higher CMTS
images support blind, time-scheduled, and guided frequency hopping.
With the release of the Cisco MC16S cable modem card, you can perform automatic upstream
frequency hopping. You can configure the MC16S to scan the upstream spectrum in your cable
network and point to “clean” available upstream channels (of a width you designate) to accept a
frequency hop.
Note The choice of spectrum is usually limited to those bands having sufficient C/N ratio and
carrier-to-ingress power ratio to support transmission of QPSK and QAM data. The MC16S card
operates with default FEC values at approximately 15 dB SNR for QPSK, and 25 dB SNR for
16QAM. Bands with known ingress should be avoided.
Higher frequency bands are also preferred because they are least likely to suffer noise interference.
Measurement of noise power levels with a spectrum analyzer is a mandatory part of the setup
procedure to characterize your cable plant.
Upstream port frequency should be set to a fixed value during system installation and testing. This
is chosen from the allocation plan for the RF domain for the RF plant segment connected to the
upstream.
Note Having fixed frequency settings is recommended during early deployment at least until
amplifier cascade adjustments or plant repair becomes infrequent for the nodes connected to the
upstream port. When multiple upstream ports are combined together to provide increased
bandwidth, care should be taken to prevent overlapping frequency bands.
When the system has reached sufficient stability, the RF domain topology can be entered into the
Cisco IOS configuration file to enable RF spectrum management. This management feature—called
spectrum groups described earlier—applies a common frequency management policy to a set of
upstream ports.
Note When each upstream port has its own RF domain, the group is called a non-shared spectrum
group. When multiple upstream ports share the same RF domain, the group is called a shared
spectrum group.
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12.0(7)XR2
Two-Way Cable
Spectrum Management Configuration Guidelines
This section presents tips, capabilities, and guidelines to keep in mind when configuring the
Cisco uBR7200 series for spectrum management.
General
In general, when defining your spectrum, be sure to take the following into consideration:
•
Avoid frequencies with known ingress problems such as amateur radio bands or short-wave
bands
•
Avoid hostile spectrum below 20 MHz for use with 16QAM because the cable network does not
support the necessary SNR.
•
•
Allow extra bands for frequency hopping
Use the receive power level setting to perform slight equalization adjustments
Using the Cisco uBR7200 series cable modem cards and Cisco IOS Release 12.0(7)XR2 CMTS
images, you can configure the router to:
•
Allocate and migrate to a new channel while in session without losing data if a predetermined
threshold is violated
•
•
Perform 15 channel migrations per second
•
Migrate frequencies based on the following conditions:
Use multiple methods to determine the need to change frequencies and multiple approaches
when migrating cable modems to a new channel; each can be configured and customized
— When using the MC16S cable modem card, if the number of lost station management
messages exceeds a predetermined threshold configured by the system administrator
— The migration event occurs on a configured daily or weekly schedule
Note Use the show cable spectrum-group command to display the current allocation table and
frequency assignments.
RF Topology Example
Following is an example topology for a Cisco uBR7223 with combiner groups designated A through
J. Combiner groups C and E have multiple upstream ports. These should be configured in a shared
spectrum group. The other upstreams should be configured in a non-shared spectrum group.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 5
Spectrum Management Overview
In this example, ten combiner groups are served with frequency hop tables from three spectrum
groups:
Cable3/0
DS +-----+ Upconverter +----- laser group 1
U0 +----- combiner group A
U1 +----- combiner group B
U2 +------combiner group C
U3 +------combiner group C
U4 +----- combiner group D
U5 +------combiner group E
Cable4/0
DS +-----+ Upconverter +----- laser group 2
U0 +------combiner group E
U1 +----- combiner group F
U2 +----- combiner group G
U3 +----- combiner group H
U4 +----- combiner group I
U5 +----- combiner group J
The laser group term refers to the set of fiber nodes that share the same downstream signal. An
optical splitter is often used to create individual feeds-per-node.
In the downstream direction, two 6 MHz channel slots are assigned. All fiber nodes in combiner
groups A-E should have a channel slot containing the downstream signal from Cable3/0. Combiner
groups A-E are said to belong to “laser group 1.”
All fiber nodes in combiner groups E-J should have a channel slot containing the downstream signal
from Cable4/0. Combiner groups E-J are said to belong to “laser group 2.”
Because combiner group E belongs to two laser groups, there should be two different downstream
channel slots for Cable3/0 and Cable4/0.
Assuming that all combiner groups use the frequency band from 20 to 26 MHz, the following
configuration enables spectrum management for all upstream ports:
cable spectrum-group 1 band 20000000 26000000
cable spectrum-group 2 shared
cable spectrum-group 2 band 20000000 26000000
cable spectrum-group 3 shared
cable spectrum-group 3 band 20000000 26000000
interface Cable3/0
cable spectrum-group 1
cable upstream 2 spectrum-group 2
cable upstream 3 spectrum-group 2
cable upstream 5 spectrum-group 3
interface Cable4/0
cable spectrum-group 1
cable upstream 0 spectrum-group 3
A description of the spectrum groups 1 through 3 follows:
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12.0(7)XR2
Two-Way Cable
•
Spectrum Group 1—This group is non-shared. Upstream RF domains exist for each member
upstream port.
Upstream
Cable3/0
Cable3/0
Cable3/0
Cable4/0
Cable4/0
Cable4/0
Cable4/0
Cable4/0
•
Port
U0
U1
U4
U1
U2
U3
U4
U5
A
B
D
F
G
H
I
J
Spectrum Group 2—This group is shared. A single upstream RF domain exists.
Upstream Port
Cable3/0 U2
Cable3/0 U3
•
RF Domain
combiner group
combiner group
combiner group
combiner group
combiner group
combiner group
combiner group
combiner group
RF Domain
combiner group C
combiner group C
Spectrum Group 3—This group is shared. A single upstream RF domain exists.
Upstream Port
Cable3/0 U5
Cable4/0 U0
RF Domain
combiner group E
combiner group E
For the 20 to 26 MHz band of each RF domain, the spectrum is channelized according to the channel
width settings of each member port. For example, if the ports U2 and U3 of Cable3/0 are set to
3.2 MHz and 1.6 MHz channel widths, respectively, then spectrum group 2 uses the following
channelization:
>
>
>
>
>
>
Channel Width Start Stop Center
(Mhz) (Mhz) (Mhz) (Mhz)
1
3.2
20.0 23.2 21.6
2*
1.6
20.0 21.6 20.8
3*
1.6
21.6 23.2 22.4
4
1.6
23.2 24.8 24.0
Note Channels 2 and 3 are not available when channel 1 is in use.
Because the group is shared, ports U2 and U3 will be assigned channels 1 and 4, respectively, to
prevent overlap.
Note There are no alternate frequency assignments for either port and bandwidth is wasted from
24.8-to-26.0 MHz. To create alternate channels, increase the upper boundary from
26.0-to-28.0 MHz.
> Channel
>
> 1
> 2
> 3
> 4
> 5
> 6
> 7
Width Start Stop Center
(Mhz) (Mhz) (Mhz) (Mhz)
3.2
20.0 23.2 21.6
3.2
23.2 26.4 24.8
1.6
20.0 21.6 20.8
1.6
21.6 23.2 22.4
1.6
23.2 24.8 24.0
1.6
24.8 26.4 25.6
1.6
26.4 28.0 27.4
Care should be taken to reduce the spectrum allocation when used with small channel widths.
Otherwise, there will be a large number of upstream channel slots.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 7
Spectrum Management Overview
For example, if the allocation is from 20.0 to 28.0 MHz and an upstream port has its channel width
set to 0.2 MHz, then there will be 40 possible slots for that channel width. Blind frequency hopping
may require quite a long time to find the clean slot since it will try each available slot, one at a time
for several seconds each try.
Cable Modem Transmit Power Adjustment
In addition to frequency, the nominal input power level of the upstream receivers can be set at the
time of frequency hop. This allows the cable operator to perform minor equalization as a function of
frequency.
cable spectrum-group 1 frequency 21600000
cable spectrum-group 1 frequency 24800000 1
cable spectrum-group 1 frequency 28000000 2
In this example, the upstream port nominal receive power at 21.6 MHz is 0 dBmV, at 24.8 MHz is
1 dBmV, and at 28.0 MHz is 2 dBmV. At any time, the power level set in the interface configuration
overrides the spectrum group power level.
Time-Scheduled Allocation
You can add spectrum on a weekly schedule by including an optional weekday and time:
cable spectrum-group 1 time Mon 08:00:00 frequency 21600000
Deletion is performed using the “delete” keyword:
cable spectrum-group 1 time Mon 18:00:00 delete frequency 21600000
If your cable plant has an upstream noise characteristic on a weekly cycle, use time-scheduled
spectrum allocation.
Upstream Frequency Migration
Per DOCSIS RFI specification section 6.3.2.2, RF channel migration occurs by broadcasting a
change in the UCD message to all cable modems. The UCD message contains the upstream
frequency and transmission parameters associated with an upstream channel.
The speed of channel migration via the UCD message is typically less than 20 ms. During that period
of time, upstream transmission is interrupted until the cable modem transmitter adjusts to its new
frequency. Data is stored in the cable modem's buffers for this brief period of time and sent when the
frequency hop is complete.
Also, per the DOCSIS RFI, station maintenance intervals are used to perform per-modem keepalive
polling. The Cisco uBR7200 series routers poll each cable modem at least once every 30 seconds,
with the default polling count of once every 25 seconds. When there are fewer than 25 modems per
downstream, the default polling rate is every modem per second. The system takes the total number
of modems to be polled every 25 seconds, and evenly distributes the number of modems polled per
second.
When ingress noise or interference causes loss of keepalive messages from a configurable
percentage of all cable modems (resulting in missed polls) connected to an MC16S with Cisco IOS
Release 12.0(7)XR2, a new frequency is selected from the allocation table and an UCD update is
performed. But, the system must wait until a hop threshold time interval has elapsed before it can
act on that hop.
The migration time is 2 msec for any upstream UCD update. Once the UCD is updated, the hop has
occurred. The system must wait the hop period until it changes the UCD a second time.
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12.0(7)XR2
Two-Way Cable
The system will not hop endlessly, because one cable modem is generating 90% of the errors and
90% of the traffic.
If the CMTS does not receive two polls in a row, it will signal a frequency hop. A single modem
missing two polls in a row counts as 10% missed polls. The CMTS polls all modems sequentially.
It waits for 20 seconds. If it misses two polls in a row again, it frequency hops again. This pattern is
repeated.
Note Regardless of the number of missed polls during the 20 second hop threshold time, it will not
hop again thus preventing endless frequency hopping.
The default threshold of 100% can be modified using the following IOS global configuration
command:
cable spectrum-group {1|2|3|...|32} frequency hop threshold {1|2|3|...|100}
The percentage threshold method prevents a single failing cable modem from affecting service to
other good cable modems. To prevent excessive frequency hop, the minimum period between hops
can be changed from the default value of 300 seconds using the following Cisco IOS global
configuration command.
cable spectrum-group {1|2|3|...|32} frequency hop period {1|2|3|...|3600}
If the destination channel is expected to be impaired, then the frequency hop period threshold can be
reduced to a small value such as 10 seconds. This allows the frequency hop to continue more rapidly
until a clear channel is found.
The current implementation is known as blind frequency hop because there is no “look-ahead”
mechanism. In this case, the search time is 0 seconds and the switching time is 20 ms.
Upstream Physical Layer Configuration
The upstream port becomes “up” when it is assigned an upstream frequency and it is configured to
be administratively up. Configuring a spectrum group enables frequency agility and disables the
fixed upstream frequency setting.
Note Frequency assignment is independent of the configured shutdown state. A configured no
cable upstream n shutdown places the port in the “adminup” state. If cable upstream n shutdown
is configured and no frequency assigned, then the port transitions to the “down” state.
Global Configuration
A maximum of 32 spectrum groups can be configured in the system. Configuring a spectrum group
allows the upstream frequency and input power level to change whenever noise impairs upstream
data traffic.
cable spectrum-group groupnum [ time day hh:mm:ss ] [delete]
frequency ctr-freq-hz power-level-dBmV
cable spectrum-group groupnum [ time day hh:mm:ss ] [delete]
band start-freq-hz end-freq-hz power-level-dBmV
groupnum
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 9
Spectrum Management Overview
Specifies the spectrum group number. (The valid range is 1 to 32.)
If the time parameter is present, then the frequency setting or band is made available or is deleted at
the specified time.
delete (Optional)
Specifies that the frequency setting or band should be removed from use at the specified time.
frequency
Specifies that a center frequency setting should be a unit of allocated spectrum in this spectrum
group.
Note A channel width of 3.2 MHz is assumed for allocation purposes. For example, if the center
frequency is configured as 20.0 MHz, then the band 18.4 to 21 MHz; 6 MHz will be added to the
allocated spectrum. This applies even if the configured channel width is smaller.
ctr-freq-hz
Upstream center frequency. Valid range is 5,000,000 to 42,000,000 Hz (5 to 42 MHz) depending on
the cable modem card used. Half of the upstream carrier energy is distributed below and the other
half above this point.
band
Specifies that a continuous band setting should be a unit of allocated spectrum in this spectrum
group.
start-free-hz
Specifies the lower boundary of a frequency band.
end-freq-hz
Specifies the upper boundary of a frequency band.
power-level-dBmV
Specifies the nominal input power level. (The valid range is -10 to +25 dBmV.)
Note Some cable plants may wish to change only the input power level and not frequency on a daily
time schedule.
no cable spectrum-group groupnum
Specifies that a given spectrum group should be deleted.
Note Member upstream ports may transition to the “down” state since there is no spectrum to
assign. Reconfigure more bands or move the upstream ports to another spectrum group to bring them
back up.
[no] cable spectrum-group n shared
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12.0(7)XR2
Two-Way Cable
“Shared” indicates that upstream ports must share the same spectrum, and, therefore, must never be
set for overlapping carriers.
Note By default, upstream may overlap for all ports in the same spectrum group if this option is not
configured.
[no] cable spectrum-group n hop period period-sec
[no] cable spectrum-group n hop threshold thres-pcnt
hop
Indicates that a frequency hop parameter is to be configured for a period.
period-sec
Valid range is 1 to 3600 seconds. This parameter limits the frequency hop rate to a configured period
value in seconds. The configured value may be returned to its default of 300 seconds using the no
keyword.
thres-pcnt
Valid range is 0 to 100 percent.
Interface Configuration
Specify upstream channel width in Hz. Valid values are 200000, 400000, 800000, 1600000, and
3200000 based on the cable modem card used. The corresponding symbol rate is 160000, 320000,
640000, 1280000, and 2560000 symbols/sec. A default value of 1600000 Hz (1280000 symbols/sec)
is configured by the no keyword.
cable upstream n channel-width width
[no] cable upstream n channel-width width
The channel width set by this command determines the amount of spectrum needed during
frequency assignment.
[no] cable upstream port shutdown
shutdown (Default)
Disables the upstream port. In this mode, downstream UCD and MAP messages for the upstream
channel are disabled which inhibits the upstream transmitters on the cable modems.
Note Shutting down the interface does not prevent frequency assignment.
no...shutdown
Enables the upstream port. The operator must configure this option to enable data traffic.
[no] cable spectrum-group groupnum
no...spectrum-group
(Default) Disable frequency agility.
groupnum
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 11
Spectrum Management Overview
Enable frequency agility and spectrum management of the upstream frequency and power. The
global spectrum group specified by groupnum defines a frequency table; otherwise, the upstream
port will assume the “down” state.
Configuring Upstream Frequencies
Upstream parameters must be configured manually. After the setup facility is run, upstream ports
have a default state of “shutdown.” To configure upstream channel frequencies, you have two
choices:
•
Configure a fixed frequency between 5 and 42 MHz for a North American HFC network and
enable the upstream port.
•
Create a global spectrum group, assign the interface to it, and enable the upstream port.
The cable modem card receiver accepts time-division multiplexed burst transmissions from cable
modems which are DOCSIS compliant. The upstream port becomes “up” when it is assigned an
upstream frequency and is configured to be administratively up.
Upstream burst parameters can be configured by defining individual modulation profiles. A
modulation profile consists of a table of physical layer characteristics for the different types of
upstream bursts, for example, initial maintenance, long grant, request/data, request, short grant, and
station maintenance.
Note Only qualified personnel should define upstream modulation profiles.
Configuring Upstream Interfaces on the MC16S Manually After You Have Run the Setup Facility
To activate upstream interfaces on the MC16S, follow these steps:
Step 1
After the setup facility has initially configured non-cable interfaces on the
Cisco uBR7200 series, get into enable (privileged EXEC) mode by entering the enable
command and your password.
For detailed information regarding the Setup Facility on the Cisco uBR7200 series
universal broadband router, refer to the “Configuring the Cisco uBR7200 Series” chapter
of the Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide.
Step 2
Enter the configure terminal command to get into global configuration mode.
Step 3
In global configuration mode, configure modulation profiles and/or spectrum groups for
your Cisco uBR7200 series using the cable modulation-profile and cable
spectrum-group commands.
For detailed information regarding parameters and allowable values for the cable
modulation-profile and cable spectrum-group commands, refer to the “cable upstream
hopping blind” section on page 26 and the “Debug Commands” section on page 31.
12
12.0(7)XR2
Step 4
To configure individual upstream interfaces on the MC16S, enter the cable upstream
interface number command to get into cable interface configuration mode.
Step 5
While in cable interface configuration mode, you can configure various characteristics for
the interface in question using the cable upstream commands defined in this feature
module in the “Command Reference” section on page 15 and the Cisco uBR7200 Series
Universal Broadband Router Cable Modem Card Installation and Configuration
document.
Benefits
Checking Your Settings and Reviewing Your Configuration Changes
You can check your settings and review any changes to your configuration using various software
commands.
To check the value of the settings you have entered, enter the show running-config command at the
Router# prompt:
Router# show running-config
To review changes you make to the configuration, use the EXEC show startup-config command to
display the information stored in NVRAM.
Viewing Your System Configuration
You can use a variety of show commands to view information specific to the hardware and cable
interface configuration on your Cisco uBR7200 series universal
broadband router. Please refer to the configuration notes that accompanied the various components
in your Cisco uBR7200 series for detailed information.
MC16S Cable Modem Card
The MC16S consists of a motherboard (based on the MC16C cable modem card) and an additional
“piggy-back” spectrum management card. The MC16S supports 256 QAM at 40 Mbps downstream
and 16 QAM at 5 Mbps upstream default data rates. The MC16S supports all DOCSIS upstream
channel widths—3.2 MHz, 1.6 MHz, 800 kHz, 400 kHz, and 200 kHz—and the card output is
+42 dBmV +/- 2 dB. In addition, the MC16S features advanced spectrum management capabilities
made possible by hardware and software enhancements.
The MC16S spectrum management daughter card is able to sample the 5-to-42 MHz upstream
spectrum and identify clean channels acceptable for a dynamic frequency hop. When a user-defined
threshold percentage of “offline” cable modems has been reached, the spectrum management card
takes a snapshot of the available upstream spectrum and then passes this information to the Cisco
IOS software, where it is analyzed for indications of significant ingress and/or impulse noise. From
this analysis, the Cisco IOS software draws informed conclusions regarding the “clean” portion(s)
of the upstream frequency spectrum and automatically initiates a frequency hop to a clean upstream
channel. The user-defined threshold value is specified by a command in the configuration file of the
Cisco uBR7200 series router.
The advanced spectrum management capabilities of the MC16S include the ability to hierarchically
scan portions of the upstream spectrum for clean channels of varying widths. For more specific
information on MC16S capabilities and programming, refer to the “Command Reference” section
on page 15.
Benefits
•
Gives you the ability to more effectively manage the upstream frequency spectrum due to fewer
cable modems falling “offline” because of excessive noise in one area of the upstream frequency
spectrum
•
•
Takes advantage of frequency hopping to a center frequency over a range of different frequencies
Provides more reliable two-way data transmission
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 13
Supported Platforms
Related Features and Technologies
Table 1 lists the Cisco IOS universal broadband router features related to the scope of this feature
module.
Table 1
Cisco uBR7200 Series Universal Broadband Router Features
Feature
IOS Release
Upstream Traffic Shaping Feature
11.3(9)NA
Blind Frequency Hopping and Time Scheduled Frequency Hopping Support
12.0(5)T1
Guided Frequency Hopping
12.0(5)T1
Enhanced Spectrum Management
12.0(5)T1
Blind Frequency Hopping Support on the MC16S Cable Modem Card
12.0(7)XR2
Signal-to-Noise Ratio Data Support
12.0(7)XR2
Upstream Spectrum Management Capabilities Expanded Using the MC16S Cable
Modem Card—MC16S Can Now Scan Upstream Spectrum for Clean Channel
Before Initiating Frequency Hop
12.0(7)XR2
Related Documents
The Cisco uBR7200 series universal broadband router is described in Cisco IOS Release 12.1 and
in the following online feature modules:
•
•
•
•
•
Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide
Cisco uBR7200 Series Universal Broadband Router Cable Modem Card Hardware Installation
Upstream Traffic Shaping Feature
Multiservice Applications Configuration Guide
Multiservice Applications Command Reference
Supported Platforms
•
•
•
Cisco uBR7223
Cisco uBR7246
Cisco uBR7246 VXR
Supported Standards, MIBs, and RFCs
Standard
No new or modified standards are supported by this feature.
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12.0(7)XR2
Supported Standards, MIBs, and RFCs
MIBs
Table 2 lists the MIBs necessary to support spectrum management functionality on Cisco uBR7200
series universal broadband routers.
Table 2
Spectrum Management MIBs Supported on Cisco uBR7200 Series Routers
MIB Filename
Description
Release
CISCO-CABLE-SPECTRUM-MIB.my
CISCO-CABLE-SPECTRUM-MIB-V1SMI.my
This module describes the spectrum management
flap list attributes.
12.0(5)T1
Note In Cisco IOS Release 12.0(7)XR2, a new table entitled “cdxIfUpstreamChannelExtTable”
was added to CISCO-DOCS-EXT-MIB supporting the use of a second channel width designation
for hierarchical spectrum analysis, as in the cable upstream interface number channel-width
width1 width2 command.
RFCs
No new or modified RFCs are supported by this feature.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 15
Command Reference
Command Reference
This section documents commands necessary to configure upstream cable interfaces for spectrum
management. Configuring your Cisco uBR7200 series universal broadband router for spectrum
management involves setting up the basic (global) attributes of your upstream interfaces as well as
specifically configuring spectrum management capability for those upstream interfaces.
Configuring Spectrum Management on an Upstream Cable Interface
To configure spectrum management capabilities for the MC16S cable modem card, you must
configure your upstream interface(s) using the following commands:
•
•
•
•
•
•
•
cable upstream hopping blind
Debug Commands
cable upstream hopping blind
cable modulation-profile
cable upstream hopping blind
cable upstream shutdown
Debug Commands
Note An upstream cable interface will not operate until you either set a fixed upstream frequency
or you create and configure a spectrum group (see the “Debug Commands” section on page 31).
16
12.0(7)XR2
Configuring Spectrum Management on an Upstream Cable Interface
cable modulation-profile
Define the elements that are used in a cable modulation profile. You can have up to 8
cable modulation profiles. Profile 1 is the default.
If you change a modulation profile, you also make changes to the physical layer.
Changing physical layer characteristics affects router performance and function; therefore, this task
should only be used by an expert user.
Caution
cable modulation-profile profile number parameter value
no cable modulation-profile
Syntax Description
profile number
Specifies the modulation profile for which you are specifying a parameter value or specifies the
number of the modulation profile you wish to remove from your router configuration. Valid
range is from 1 to 8.
parameter
• The modulation profile values that can be changed are:
• Interval usage code (iuc)—Valid values are initial, long, reqdata, request, short, station.
To use the cable modulation-profile command correctly, enter a line with all parameters for
each upstream burst type. An incomplete burst profile causes unreliable operation, or loss of
modem connectivity.
Errors or incompatible configurations in the burst profile(s) cause modems to either drop
connectivity, drop short or long data packets, or 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.
• Fec-tbytes—The number of bytes that can be corrected per FEC codeword. Valid range is
0 to 10 bytes, where 0 means no FEC.
The data rates 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.
• Fec-len—FEC codeword length. Valid range is 8 to 254 bits.
• Burst-len—Maximum burst length in bytes. 0 means no limit on burst length.
• Guard-t—Guard time in symbols. The time between successive bursts.
• Mod—Modulation. Valid values are 16qam and qpsk.
• Scrambler—Enable or disable scrambler. Valid values are scrambler and no-scrambler.
Turning the scrambler off can cause packet loss, and is only used in lab testing environments.
• Seed—Scrambler seed in hexadecimal format. Valid range is 0x0000 to 0x7FFF.
• Diff—Enable or disable differential encoding. Valid values are diff and no-diff.
• Pre-len—Preamble length in bits. Valid range is 2 to 128 bits.
• Last-cw—Handling of FEC for last codeword. Valid values are fixed for fixed codeword
length and shortened for shortened last code word.
• Uw-len—Upstream unique word length. Enter uw8 for 8-bit unique words or uw16 for 16-bit
unique code words.
value
The value for the parameter you are assigning to a given modulation profile.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 17
Command Reference
Default
Modulation profile 1
Command Mode
Global configuration
Command History
Release
Modification
12.0(5)T1
This command was introduced.
Example
The following example to specifies a FEC codeword length of 200 to modulation profile 2:
Router(config)# cable modulation-profile 2 fec-len 200
The following example removes modulation profile 2 from your router configuration:
Router(config)# no cable modulation-profile 2
Related Commands
18
12.0(7)XR2
Command
Description
cable modulation-profile
Specifies the center frequency for a given upstream cable interface.
cable upstream hopping blind
Specifies the channel width of the given upstream cable interface.
cable upstream hopping blind
Specifies the upstream cable interface receive power level in dBmV.
cable upstream shutdown
Activates or shuts down a specified upstream cable interface.
Debug Commands
Configures spectrum management characteristics for the given spectrum
group.
Debug Commands
Disengages the advanced spectrum management features of the MC16S cable
modem card by enabling blind frequency hopping behavior.
Configuring Spectrum Management on an Upstream Cable Interface
cable spectrum-group
Frequency agility is configured and activated using spectrum groups that are controlled by the
spectrum manager. You can create from 1 to 32 spectrum groups for each cable modem card
upstream port.
To create spectrum groups, specify a list of upstream frequencies and nominal power levels that each
spectrum group can use when an upstream frequency change is necessary. Each spectrum group
should have its own list of upstream frequencies. At 1.6 MHz, the valid range is –10 dBmV to
25 dBmV. The power level value should only be changed if you want to change only the power level
as part of spectrum management. The standard power level is 0 dBmV.
Note You must repeat this command for each frequency or power level that you want to add to a
spectrum group’s list of valid values.
After you have created one or more spectrum groups for your cable network, you can add
characteristics to them, providing you with more definitive control over frequency usage and
frequency hopping.
Note The cable interface will not operate until you either create and configure a spectrum group or
set a fixed upstream frequency. See the “cable upstream hopping blind” section on page 26.
cable spectrum-group group number parameter value
no cable spectrum-group group number
Syntax Description
group number
Specifies the spectrum group for which you are specifying a parameter value or specifies
the number of the spectrum group you wish to remove from your router configuration.
Valid range is from 1 to 32.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 19
Command Reference
parameter
The spectrum group values that can be changed or added are:
• Frequency—Specifies the center frequency for the given spectrum group. Entering
additional cable spectrum-group group number frequency commands for the same
spectrum group will create a collection of allowable center frequencies for spectrum
group hopping.
• Band—Specifies a range of center frequencies the Cisco uBR7200 series can scan in
order to find an acceptable channel to which the spectrum group may hop.
The spectrum management daughter card on the MC16S can use the frequency
range you specify in this command line to scan a range of frequencies for possible
automatic hop, instead of having to specify a number of individual frequencies using the
cable spectrum-group group number frequency command.
Note
• Time—Specifies a time of day that the Cisco uBR7200 series should automatically
perform a frequency hop for the given upstream spectrum group.
The time command can be combined with the frequency and band commands, as
shown in the “Example” section on page 20.
Note
• Hop period—Specify the minimum period (in seconds) before which a frequency hop
can occur.
• Hop threshold—The threshold value (expressed as a percentage) of the number of
“offline” modems identified before the Cisco uBR7200 series initiates an automatic
frequency hop.
• Shared—Specify that a particular spectrum group is a shared RF spectrum group.
Specifying a given spectrum group as “shared” tells the Cisco uBR7200 series that
you want to be sure that upstream frequencies assigned to upstream interfaces are not
assigned to additional upstream interfaces.
value
The corresponding parameter value for the parameter you are defining for a given
spectrum group.
Default
None.
Command Mode
Global configuration
Command History
20
12.0(7)XR2
Release
Modification
12.0(5)T1
This command was introduced.
12.0(7)XR2
The band parameter for this command was added to enable frequency
range scanning capabilities in the MC16S cable modem card.
Configuring Spectrum Management on an Upstream Cable Interface
Example
See the following example to configure spectrum group 1 with an upstream frequency of
6,500,000 Hz and a default power level of 0 dBmV:
Router(config)# cable spectrum-group 1 frequency 6500000
See the following example to add the upstream frequency 7,000,000 Hz to the list of valid
frequencies with a default power level of 0 dBmV for spectrum group 1:
Router(config)# cable spectrum-group 1 frequency 7000000
See the following example to configure spectrum group 2 with an upstream frequency 7,500,000 Hz
and change the power level to 5 dBmV:
Router(config)# cable spectrum-group 2 frequency 7500000 5
See the following example to configure spectrum group 3 with an upstream band of 12,000,000 to
18,000,000 Hz and default power level of 0 dBmV:
Router(config)# cable spectrum-group 3 band 12000000 18000000
See the following example to add the upstream band 20,000,000 to 24,000,000 Hz to the list of valid
bands with a change in the power level of 13 dBmV for spectrum group 3:
Router(config)# cable spectrum-group 3 band 20000000 24000000 13
See the following example to configure a continuous band between 5,000,004 and 40,000,000 Hz
for scheduled spectrum group 4 with a default power level of 0 dBmV. The spectrum group will be
available to the spectrum group starting at 12:00 p.m. local time each Monday:
Router(config)# cable spectrum-group 4 time Monday 12:00:00 band 5000004 40000000
See the following example to add the upstream frequency 9,500,000 Hz to the list of valid
frequencies and change the nominal power level to 5 dBmV. The spectrum manager adjusts
frequencies and power levels on this group at 2:00 a.m. local time each day:
Router(config)# cable spectrum-group 3 time 02:00:00 frequency 9500000 5
See the following example to configure the minimum period before which a frequency hop can occur
in seconds:
Router(config)# cable spectrum-group 3 hop period 800
See the following example to configure the threshold value (expressed as a percentage) of the
number of “offline” modems identified before the Cisco uBR7200 series initiates an automatic
frequency hop:
Router(config)# cable spectrum-group 3 hop threshold 40
See the following example to configure a particular spectrum group as a shared RF spectrum group.
Specifying a given spectrum group as “shared” tells the Cisco uBR7200 series that you want to be
sure that upstream frequencies assigned to upstream interfaces are not assigned to additional
upstream interfaces:
Router(config)# cable spectrum-group 3 shared
See the following example to remove a specified spectrum group from your configuration:
Router(config)# no cable spectrum-group 3
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 21
Command Reference
Related Commands
22
12.0(7)XR2
Command
Description
cable modulation-profile
Specifies the center frequency for a given upstream cable interface.
cable upstream hopping blind
Specifies the channel width of the given upstream cable interface.
cable upstream hopping blind
Configures preset modulation profiles that you can apply to one or more
upstream cable interfaces when you identify and configure spectrum groups.
cable upstream hopping blind
Specifies the upstream cable interface receive power level in dBmV.
cable upstream shutdown
Activates or shuts down a specified upstream cable interface.
Debug Commands
Disengages the advanced spectrum management features of the MC16S cable
modem card by enabling blind frequency hopping behavior.
Configuring Spectrum Management on an Upstream Cable Interface
cable upstream channel-width
Enter the channel width in hertz (Hz). Valid values are 200000 Hz (160 kilosymbols per second
[ksps]), 400000 Hz (320 ksps), 800000 Hz (640 ksps), 1600000 Hz (1280 ksps), and 3200000 Hz
(2560 ksps). The default is 1600000 Hz.
The MC16S cable modem card features advanced spectrum management capability that allows you
to scan the upstream spectrum for clean channel widths of varying size. By entering an optional
second channel width value in the appropriate command line, you can instruct the MC16S to
hierarchically search for clean upstream channels of 3.2 MHz, 1.6 MHz, 800 kHz, 400 kHz, and
200 kHz width. The spectrum management card on the MC16S will scan the upstream spectrum for
clean (usable) channels of the greatest specified width. If no acceptable channels of the specified
width can be found, the spectrum management card automatically begins to scan the upstream
spectrum for the next largest available channel width. For example, if the spectrum management card
is unable to find a usable 1.6 MHz upstream channel, it will automatically begin searching for usable
800 kHz channels. To ensure that only one specified upstream channel width is ever used in a given
upstream segment leading to an MC16S, simply enter the same channel width twice in the
appropriate command line.
Note If you change the channel width, the symbol rate changes accordingly
(channel width = 1.25 * symbol rate). Higher symbol rates are more susceptible to RF noise and
interference. If you use a symbol rate or modulation format beyond the capabilities of your HFC
network, you might experience packet loss or loss of cable modem connectivity.
Note For QAM-16 channel widths of 400 kHz (320 ksps) or greater, Cisco recommends that you
use 16-QAM modulation only for long and short data and that you use QPSK for request, initial, and
station communication. For QAM-16 channel widths of 200 kHz (160 ksps), all communication
must be able to use 16-QAM. That is, 160 ksps with 16-QAM requires an exceptional signal-to-noise
ratio (SNR) in your upstream channel(s). When you use QAM-16 for request, initial, and station
maintenance messages with channel widths greater than 400 kHz, the QAM-16 preamble and
message data takes longer to transmit than the QPSK format. To change the modulation values, see
the “cable upstream hopping blind” section on page 26.
To specify an upstream channel width, use the cable upstream channel-width interface
configuration command. Use the no form of this command to set the channel width to 1600000 for
a port number.
cable upstream portnum channel-width width1 width2
no cable upstream portnum channel-width
Syntax Description
portnum
Specifies the port number.
width1
Specifies upstream channel width in hertz (Hz). Valid values are
200000 (160000 symbols/sec), 400000 (320000 symbols/sec),
800000 (640000 symbols/sec), 1600000 (1280000 symbols/sec),
and 3200000 (2560000 symbols/sec).
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 23
Command Reference
width2
Specifies the smallest width in hertz (Hz) for this upstream
channel. Valid values are 200000 (160000 symbols/sec), 400000
(320000 symbols/sec), 800000 (640000 symbols/sec), 1600000
(1280000 symbols/sec), and 3200000 (2560000 symbols/sec).
Default
1600000 (1280 Ksymbols/sec)
Command Mode
Cable interface configuration
Command History
Release
Modification
11.3 NA
This command was introduced.
12.0(7)XR2
The width2 option was added.
Example
See the following example to configure port 2 with a channel width of 3,200,000 Hz and limit the
channel width to be no smaller than 400,000 Hz:
Router(config-if)# cable upstream 2 channel-width 3200000 400000
Note The upstream 2 command can be abbreviated as u2.
Related Commands
24
12.0(7)XR2
Command
Description
cable modulation-profile
Specifies the center frequency for a given upstream cable interface.
cable upstream hopping blind
Configures preset modulation profiles that you can apply to one or more
upstream cable interfaces when you identify and configure spectrum groups.
cable upstream hopping blind
Specifies the upstream cable interface receive power level in dBmV.
cable upstream shutdown
Activates or shuts down a specified upstream cable interface.
Debug Commands
Configures spectrum management characteristics for the given spectrum
group.
Debug Commands
Disengages the advanced spectrum management features of the MC16S cable
modem card by enabling blind frequency hopping behavior.
Configuring Spectrum Management on an Upstream Cable Interface
cable upstream frequency
Enter a fixed frequency of the upstream RF carrier for an upstream port. You can also select a default
that does not set a specific fixed value. The valid range for a fixed upstream frequency is
5,000,000 Hz to 42,000,000 Hz (5 to 40 MHz). The Cisco uBR7200 series will command the
cable modems to use this frequency as the center frequency.
Note Some cable systems cannot reliably transport frequencies near these band edges. The wider
the upstream channel (in MHz), the more difficulty you could have. Enter a center frequency
between 20 and 38 MHz if you have difficulty.
cable upstream interface number frequency frequency
no cable upstream interface number frequency frequency
Syntax Description
interface number
Specifies the upstream interface on the cable modem card for
which you want to assign an upstream frequency.
frequency
Specifies the center frequency (in Hz) for the given upstream
interface. Acceptable values range from 5000000 to 42000000. If
you wish to have the Cisco uBR7200 series dynamically specify a
center frequency for the given upstream interface, you can elect
not to enter any frequency value.
Default
Dynamic (no fixed frequency)
Command Mode
Cable interface configuration
Command History
Release
Modification
11.3 NA
This command was introduced.
Example
See the following example to allow the Cisco uBR7200 series to dynamically specify a center
frequency upstream interface 0:
Router(config-if)# cable upstream 0 frequency
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 25
Command Reference
See the following example to specify a center frequency of 24.016 MHz on upstream interface
port 0:
Router(config-if)# cable upstream 0 frequency 24016000
Note The upstream 0 command can be abbreviated as u0.
Related Commands
26
12.0(7)XR2
Command
Description
cable upstream hopping blind
Specifies the channel width of the given upstream cable interface.
cable upstream hopping blind
Configures preset modulation profiles that you can apply to one or more
upstream cable interfaces when you identify and configure spectrum groups.
cable upstream hopping blind
Specifies the upstream cable interface receive power level in dBmV.
cable upstream shutdown
Activates or shuts down a specified upstream cable interface.
Debug Commands
Configures spectrum management characteristics for the given spectrum
group.
Debug Commands
Disengages the advanced spectrum management features of the MC16S cable
modem card by enabling blind frequency hopping behavior.
Configuring Spectrum Management on an Upstream Cable Interface
cable upstream hopping blind
To override hop decisions, enter the cable upstream hopping blind interface configuration
command. To stop blind hopping, enter the no form of this command.
cable upstream interface number hopping blind
no cable upstream interface number hopping blind
Syntax Description
interface number
Specifies the number of the upstream cable interface for which blind
frequency hopping will be activated.
Defaults
Disabled
Command Mode
Cable interface configuration
Command History
Release
Modification
12.0(7)XR2
This command was introduced.
Usage Guidelines
Enter this command to override the hardware spectrum manager’s decision to optimize hopping.
Note Do not use this command unless you have a specific reason to disable optimum hopping
configurations. For example, if you are experimenting with an MC16S card, you can use this
command to enforce blind hopping on individual upstream channels.
Example
router(config-if)# cable upstream 0 hopping blind
Related Commands
Command
Description
cable modulation-profile
Specifies the center frequency for a given upstream cable interface.
cable upstream hopping blind
Specifies the channel width of the given upstream cable interface.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 27
Command Reference
28
12.0(7)XR2
Command
Description
cable upstream hopping blind
Configures preset modulation profiles that you can apply to one or more
upstream cable interfaces when you identify and configure spectrum groups.
cable upstream hopping blind
Specifies the upstream cable interface receive power level in dBmV.
cable upstream shutdown
Activates or shuts down a specified upstream cable interface.
Debug Commands
Configures spectrum management characteristics for the given spectrum
group.
Configuring Spectrum Management on an Upstream Cable Interface
cable upstream power-level
Enter the nominal input power level for the upstream RF carrier in decibels per millivolt (dBmV).
You can also select the default of 0 dBmV, which is the optimal setting for the upstream power level.
The valid range for the input power level depends on the data rate. At 1.6 MHz, the valid range is
–10 dBmV to 25 dBmV. If your power levels operate at greater than the maximum valid level, you
must use an inline attenuator to bring the power level to within the valid range.
If you increase the input power level, the cable modems on your HFC network increase
their transmit power level. This increases the C/N ratio on the network, but also increases distortion
products. CSO and CTB/CX0 values worsen by 2 dB for every 1 dB-increased C/N. The return path
laser immediately enters a non-linear mode called clipping and all communication is no longer
reliable. Many return lasers send “short” bursts well above the clipping thresholds and fail on longer
or successive bursts.
Caution
It is almost impossible to see CSO and CTB/CX0 products on a lightly loaded HFC network.
Approximately 70-90% upstream traffic utilization is required if you directly measure these products
using a spectrum analyzer. Be careful if you adjust this parameter.
You should not adjust your input power level by more than 5 dB in a 30-second interval. If you
increase the power level by more than 5 dB within 30 seconds, cable modem service on your
network will be disrupted. If you decrease the power level by more than 5 dB within 30 seconds,
cable modems on your network will be forced offline.
Note When you run cable upstream 0 power-level, Cisco recommends that the adjacent channel
not have a large variation. The recommended maximum input power variance is 5 to 6 dBmV.
cable upstream interface number power-level power
no cable upstream interface number power-level
Syntax Description
interface number
Specifies the upstream cable interface for which you are
assigning the given power level
power
Specifies the power level for the given upstream interface
Default
0 dBmV
Command Mode
Cable interface configuration
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 29
Command Reference
Command History
Release
Modification
11.3 NA
This command was introduced.
Example
The following example configures a power level of 2 dBmV to upstream cable interface 0:
Router(config-if)# cable upstream 0 power-level 2
The following example sets the upstream power level for cable interface 0 to the default setting of
0 dBmV:
Router(config-if)# no cable upstream 0 power-level
Note The upstream 0 command can be abbreviated as u0.
Related Commands
30
12.0(7)XR2
Command
Description
cable modulation-profile
Specifies the center frequency for a given upstream cable interface.
cable upstream hopping blind
Specifies the channel width of the given upstream cable interface.
cable upstream hopping blind
Configures preset modulation profiles that you can apply to one or more
upstream cable interfaces when you identify and configure spectrum groups.
cable upstream shutdown
Activates or shuts down a specified upstream cable interface.
Debug Commands
Configures spectrum management characteristics for the given spectrum
group.
Debug Commands
Disengages the advanced spectrum management features of the MC16S cable
modem card by enabling blind frequency hopping behavior.
Configuring Spectrum Management on an Upstream Cable Interface
cable upstream shutdown
Activate the RF carrier on the upstream ports. Each upstream port must be activated to enable
upstream data from the cable modems on the HFC network to the Cisco uBR7200 series.
Note The upstream cable interface will not operate until you either set a fixed upstream frequency
or you create and configure a spectrum group (see the “Debug Commands” section on page 31).
cable upstream interface number shutdown
no cable upstream interface number shutdown
Syntax Description
interface number
Specifies the number of the upstream cable interface you are
activating or deactivating.
Default
Cable interfaces are deactivated until the no shutdown command has been issued for them.
Command Mode
Cable interface configuration
Command History
Release
Modification
11.3 NA
This command was introduced.
Example
The following example deactivates a specified upstream cable interface:
Router(config-if)# cable upstream 0 shutdown
The following example activates a specified upstream cable interface:
Router(config-if)# no cable upstream 0 shutdown
Note The upstream 0 command can be abbreviated as u0.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 31
Debug Commands
Related Commands
Command
Description
cable modulation-profile
Specifies the center frequency for a given upstream cable interface.
cable upstream hopping blind
Specifies the channel width of the given upstream cable interface.
cable upstream hopping blind
Configures preset modulation profiles that you can apply to one or more
upstream cable interfaces when you identify and configure spectrum groups.
cable upstream hopping blind
Specifies the upstream cable interface receive power level in dBmV.
Debug Commands
Configures spectrum management characteristics for the given spectrum
group.
Debug Commands
Disengages the advanced spectrum management features of the MC16S cable
modem card by enabling blind frequency hopping behavior.
Debug Commands
This section documents the new debug cable hw-spectrum command. All other commands used
with this feature are documented in the Cisco IOS Release 12.1 T command reference
publications.
32
12.0(7)XR2
debug cable hw-spectrum
debug cable hw-spectrum
To display debug messages for spectrum management information, use the debug cable
hw-spectrum EXEC command. To disable the display of this information, use the no form of this
command.
[no] debug cable hw-spectrum
Syntax Description
This command has no arguments or keywords.
Default
No default behavior or values.
Command History
Release
Modification
12.0 T
This command was introduced as the debug cable specmgmt command.
12.0(5)T1
Command renamed to the debug cable hw-spectrum command.
12.0(5)T1
Command included on mainline release.
12.0(7)XR2
Command included on this special release.
Example
Lab-CMTS# debug cable hw-spectrum
CMTS spectrum analyzer debugging is on
Related Commands
Command
Description
debug cable freqhop
Displays messages for frequency hopping.
Cisco uBR7200 Series MC16S Cable Modem Card Spectrum Management 33
Debug Commands
34
12.0(7)XR2