Cisco uBR10012 Universal Broadband Router Software Configuration Guide
Chapter 6: Troubleshooting the System
Downloads: This chapterpdf (PDF - 480.0KB) The complete bookPDF (PDF - 6.42MB) | Feedback

Troubleshooting the System

Table Of Contents

Troubleshooting the System

Understanding show Command Responses

show cable flap-list

Show cable modem

show cable modem maintenance

Cisco Broadband Cable Command Reference Guideshow cable qos profile

show interface cable

show interface cable sid

show cable modulation-profile

Using a Headend CM to Verify Downstream Signals

Performing Amplitude Averaging

Enabling or Disabling Power Adjustment

Setting Frequency Threshold to Affect Power Adjustment

Setting Downstream Test Signals

Configuring Unmodulated Test Signals

Configuring PRBS Test Signals

Verifying Test Signal Output

Pinging Unresponsive CMs

Pinging a CM

Verifying the Ping

Using Cable Interface debug Commands

debug cable arp

debug cable error (for MAC Protocol Errors)

debug cable keyman (for Baseline Privacy Activity)

debug cable mac-messages

debug cable map

debug cable phy

debug cable privacy (for Baseline Privacy)

debug cable qos

debug cable range (for Ranging Messages)

debug cable receive (for Upstream Messages)

debug cable reg (for Modem Registration Requests)

debug cable reset (for Reset Messages)

debug cable specmgmt (for Spectrum Management)

debug cable startalloc (for Channel Allocations)

debug cable transmit (for CMTS Transmissions)

debug cable ucc (for Upstream Channel Change Messages)

debug cable ucd (for Upstream Channel Description Messages)


Troubleshooting the System


This chapter contains troubleshooting information for various functions of your Cisco uBR10000 series Cable Modem Termination System (CMTS) and includes the following sections:

Section
Purpose

"Understanding show Command Responses" section

Provides show command options for deriving system information.

"Using a Headend CM to Verify Downstream Signals" section

Uses a Cisco uBR924 cable access modem to verify the downstream signal originating from a Cisco uBR10012 router.

"Performing Amplitude Averaging" section

The system uses an averaging algorithm to determine the optimum power level for a CM with low carrier-to-noise ratio that is making excessive power adjustments—known as flapping. This section shows how you can interpret these power adjustments as indicating unstable return path connections.

"Setting Downstream Test Signals" section

Provides configuration commands that allow you to create downstream test signals.

"Pinging Unresponsive CMs" section

Allows a cable system administrator to quickly diagnose the health of a channel between the Cisco uBR10000 series cable interface and the CM.

"Using Cable Interface debug Commands" section

Provides instructions for troubleshooting cable interface line cards.



Note For detailed information about troubleshooting your CMTS platform using cable flap lists, refer to the chapter "Flap List Troubleshooting for the Cisco CMTS" in the Cisco Cable Modem Termination Feature Guide on Cisco.com.



Note For additional online troubleshooting resources, visit the Cisco Technical Assistance Center's Troubleshooting Assistant Web page at http://te.cisco.com/SRVS/CGI-BIN/WEBCGI.EXE?New,KB=Cable.


Understanding show Command Responses

This section summarizes cable-related show commands. For additional command information about these and other CMTS commands, refer to these additional resources on Cisco.com:

Cisco Broadband Cable Command Reference Guide

Cisco Cable Modem Termination System Feature Guide

show cable flap-list

To display the cable flap-list on a Cisco uBR10012 router, use the show cable flap-list command in privileged EXEC mode.

show cable flap-list

show cable flap-list cable slot/port [upstream port] [sort-flap | sort-time]

show cable flap-list sort-interface [sort-flap | sort-time]

Syntax Description

cable slot/port

(Optional) Displays the flap list for a particular cable interface.

upstream port

(Optional) Displays the flap list for a particular upstream on the selected cable interface.

sort-interface

(Optional) Displays the flap list for all cable interfaces, sorted by interface.

sort-flap

(Optional) Sorts the list by the number of times the CM has flapped.

sort-time

(Optional) Sorts the list by the most recent time the CM is detected to have flapped.


For the Cisco uBR10012 router, the sort option applies to one line card at a time, then the list is merged together. For example, the flap list is sorted for cable7/0/0, appears on the console, and then is sorted for cable 7/0/1, which then appears on the console, and so on.

The show cable flap-list and show cable modem commands indicate when the Cisco uBR10012 router has detected an unstable return path for a particular modem and has compensated with a power adjustment. An asterisk (*) appears in the power-adjustment field for a modem when a power adjustment has been made; an exclamation point appears when the modem has reached its maximum power transmit level and cannot increase its power level any further.

Examples

The following example shows the output of the show cable flap-list command:

Router# show cable flap-list
MAC Address     Upstream     Ins   Hit   Miss  CRC   P-Adj Flap  Time
 0010.7bb3.fd19  Cable5/0/U1  0     2792  281   0    *45    58    Jul 27 16:54:50
 0010.7bb3.fcfc  Cable5/0/U1  0     19    4     0    !43    43    Jul 27 16:55:01
 0010.7bb3.fcdd  Cable5/0/U1  0     19    4     0    *3     3     Jul 27 16:55:01
 
   

Note The asterisk (*) in the P-Adj field indicates that a power adjustment has been made for that CM. The exclamation point (!) indicates that the CM has reached its maximum power transmit level and cannot increase its power level further.


The following example shows the return for flap-list tables sorted by MAC address and by time:

Router# show cable flap-list sort-flap
Mac Addr       CableIF    Ins    Hit   Miss    CRC  P-Adj   Flap    Time
.1eab.2c0b     C6/0/0 U0    108    318     27      0      0    108 Sep 10 15:26:56 
.1eb2.bb07     C6/0/0 U0      0    293     31      1      1      1 Sep 10 15:15:49
.7b6b.71cd     C6/0/0 U0      1    288     32      0      0      1 Sep 10 15:12:13
.1eb2.bb8f     C6/0/0 U0      1    295     30      0      0      1 Sep 10 15:11:44
 
   
Router# show cable flap-list sort-time
Mac Addr       CableIF    Ins    Hit   Miss    CRC  P-Adj   Flap    Time
00e0.2222.2202 C4/0/0 U0    464   2069    242      0    421    885 Oct 16 22:47:23
0010.7b6b.57e1 C4/0/0 U0      0   2475     43      0   1041   1041 Oct 16 22:47:04
 
   

For additional information about using cable flap lists, refer to the chapter "Flap List Troubleshooting for the Cisco CMTS" in the Cisco Cable Modem Termination System Feature Guide on Cisco.com.

Show cable modem

To display information for the registered and unregistered CMs, use the show cable modem command in privileged EXEC mode.

show cable modem [ip-address | interface | mac-address] [options]

Some command options differ between the Cisco uBR10012 router (Cisco IOS Release 12.2 XF) and the Cisco uBR7200 series routers (Cisco IOS 12.1 EC).


Note Commencing with Cisco IOS Release 12.0(7)XR and 12.1(1a)T1, the output of this command was enhanced to show that the Cisco CMTS has detected an unstable return path for a particular CM and has compensated with a power adjustment.


An asterisk (*) appears in the p-adj (power adjustment) field for a modem when a power adjustment has been made.

An exclamation point (!) appears when the modem has reached its maximum power transmit level and cannot increase its power level any further.

Syntax Description

ip-address

Identifies the IP address of a specific modem to be displayed.

interface

Displays all CMs on a specific CMTS cable interface.

mac-address

Identifies the MAC address of a specific CM to be displayed.

Available options when displaying information for a cable interface or for a single CM

access-group

Displays access group.

connectivity

Displays connectivity content.

counters

Displays cable counters.

errors

Displays error details for one or all CMs.

flap

Displays flap content.

mac

Displays the DOCSIS MAC version and capabilities.

maintenance

Displays station maintenance error statistics.

offline

Displays CMs that are offline.

phy

Displays the phy layer content.

registered

Displays information for CMs that have registered with the CMTS.

remote-query

Displays the signal-noise ratio (SNR) and power statistics that the CMTS has acquired from polling the CMs. NOTE - In Cisco 12.1 CX and above, the phy option should be used instead of the remote-query option.

summary

Displays the total number, number of active, and number of registered modems per interface. This option can be used with total and upstream options to display details for specific line cards and ports.

unregistered

Displays information for CMs that have not registered with the CMTS.

verbose

Displays detailed information, replacing the former detail option, and providing information such as:

Signal-to-noise ratio (SNR) information for each CM on each interface

Summary display of the total number of modems connected for each upstream channel

Total number of registered and unregistered modems for the specified interface or upstream

Total number of offline modems for the specified interface or upstream and status for each offline modem before it went offline

Available options when displaying information for a single CM

classifiers

Displays the classifiers for the modem.

classifiers cache

Displays the classifiers in the cache maintained for each CM. (This cache is based on IP header field values and speeds up classifier lookups and reduces per packet processing overhead.)

classifiers verbose

Displays detailed information for the modem's classifiers.

cpe

Displays the CPE devices accessing the cable interface through the CM.

cnr

(For Cisco uBR-MC16S only) Displays the upstream carrier/noise ratio (CNR) for the specified CM (in dB).


Examples

The following sample output from the show cable modem command shows the default CM displays for individual CM.

Router# show cable modem 
 
   
MAC Address    IP Address      I/F     MAC         Prim RxPwr Timing Num  BPI
                                       State       Sid  (db)  Offset CPEs Enbld
0010.7b6b.58c1 0.0.0.0         C4/0/0/U5 offline     5   -0.25  2285   0    yes
0010.7bed.9dc9 0.0.0.0         C4/0/0/U5 offline     6   -0.75  2290   0    yes
0010.7bed.9dbb 0.0.0.0         C4/0/0/U5 offline     7    0.50  2289   0    yes
0010.7b6b.58bb 0.0.0.0         C4/0/0/U5 offline     8    0.00  2290   0    yes
0010.7bb3.fcd1 10.20.113.2     C5/0/0/U5 online      1    0.00  1624   0    yes
0010.7bb3.fcdd 0.0.0.0         C5/0/0/U5 init(r1)    2   -20.00 1624   0    no 
0010.7b43.aa7f 0.0.0.0         C5/0/0/U5 init(r2)    3    7.25  1623   0    no 
 
Router# show cable modem 0010.7bb3.fcd1 
MAC Address    IP Address      I/F     MAC         Prim RxPwr Timing Num  BPI
                                       State       Sid  (db)  Offset CPEs Enbld
0010.7bb3.fcd1 10.20.113.2     C5/0/0/U5 online      1    0.00  1624   0    yes
 

The following example shows sample output for the verbose option for a particular CM:

Router# show cable modem 0010.7bb3.fcd1 verbose      
MAC Address                         : 0010.7bb3.fcd1
IP Address                          : 10.20.113.2
Prim Sid                            : 1
Interface                           : C5/0/0/U5
Upstream Power                      : 0 dBmV (SNR = 33.25 dBmV)
Downstream Power                    : 0 dBmV (SNR = ----- dBmV)
Timing Offset                       : 1624
Received Power                      :   0.25
MAC Version                         : DOC1.0
Capabilities                        : {Frag=N, Concat=N, PHS=N, Priv=BPI}
Sid/Said Limit                      : {Max Us Sids=0, Max Ds Saids=0}
Optional Filtering Support          : {802.1P=N, 802.1Q=N}
Transmit Equalizer Support          : {Taps/Symbol= 0, Num of Taps= 0}
Number of CPEs                      : 0(Max CPEs = 0)
Flaps                               : 373(Jun 1  13:11:01)
Errors                              : 0 CRCs, 0 HCSes
Stn Mtn Failures                    : 0 aborts, 3 exhausted
Total US Flows                      : 1(1 active)
Total DS Flows                      : 1(1 active)
Total US Data                       : 1452082 packets, 171344434 bytes
Total US Throughput                 : 0 bits/sec, 0 packets/sec
Total DS Data                       : 1452073 packets, 171343858 bytes
Total DS Throughput                 : 0 bits/sec, 0 packets/sec
 

For additional information, examples, command history and related commands, refer to the Cisco Broadband Cable Command Reference Guide on Cisco.com.

show cable modem maintenance

To display station maintenance error statistics, use the show cable modem maintenance command in privileged EXEC mode.

show cable modem maintenance

Syntax Description

maintenance

Displays station maintenance error statistics.


When a CM is detected to be offline by the CMTS—no reply after 16 retries of station maintenance requests—the CM is marked offline. Besides marking the CM and service identifier (SID) state offline, the SID is removed immediately from the CMTS ranging list, and an aging timer is started to clean up the SID completely if the CM does not attempt to come online within the next 24 hours.

Output fields are described below:

The SM Exhausted Count value refers to the number of times a CM was dropped because it did not reply to station maintenance requests. A CM is removed from the station maintenance list after 16 times of periodic ranging opportunity without seeing the RNG_REQ from the modem.

The SM Aborted Count value refers to the number of times the CM was dropped because its operational parameters were unacceptable. This includes such reasons as the power level is outside the acceptable range, or the timing offset keeps changing. The respective times in the command output indicate when this happened.

Examples

The following example shows sample output for the maintenance option for a particular CM:

Router# show cable modem 0010.7bb3.fcd1 maintenance
 
   
MAC Address    I/F         Prim  SM Exhausted          SM Aborted
                           Sid   Count Time            Count Time
0010.7bb3.fcd1 C5/0/0/U5     1     3     Jun 1  10:24:52 0     Jan 1  00:00:00
 

Cisco Broadband Cable Command Reference Guideshow cable qos profile

To display quality-of-service (QoS) profiles for a Cisco CMTS, use the show cable qos profile command in privileged EXEC mode.

show cable qos profile profile-index [verbose]


Note Commencing with Cisco IOS Release 12.0(7)XR, the verbose option was added. Commencing with Cisco IOS Release 12.1(4)CX, this command was deprecated for DOCSIS 1.1 use because DOCSIS 1.1 replaces the QoS profile model with a service flow model. The show interface cable qos paramset command is used for DOCSIS 1.1 operation.


Syntax Description

profile-index

Displays cable QoS table. Valid range is 1 to 255.

verbose

Displays detail information about the quality-of-service profiles.


Examples

The following example displays the QoS tables for profiles 1, 2, 3, and 4:

Router# show cable qos profile
 
   
Service Prio Max       Guarantee Max        Max tx TOS  TOS   Create     B
class        upstream  upstream  downstream burst  mask value by         priv
             bandwidth bandwidth bandwidth                               enab
1       0    0         0         0          0      0x0  0x0   cmts       no
2       0    64000     0         1000000    0      0x0  0x0   cmts       no
3       0    1000      0         1000       0      0x0  0x0   cmts       no
4       7    2000000   100000    4000000    0      0x0  0x0   cm         yes
 

The following example displays verbose output for profile 1:

Router# show cable qos profile verbose
 
   
hccp-server# show cable qos profile verbose
Profile Index                           1
Name                                    Default
Upstream Traffic Priority               0
Upstream Maximum Rate (bps)             0
Upstream Guaranteed Rate (bps)          0
Unsolicited Grant Size (bytes)          0
Unsolicited Grant Interval (usecs)      0
Upstream Maximum Transmit Burst (bytes) 0
IP Type of Service Overwrite Mask       0x0
IP Type of Service Overwrite Value      0x0
Downstream Maximum Rate (bps)           0
Created By                              cmts(r)
Baseline Privacy Enabled                no 
 

For additional information, examples, command history and related commands, refer to the Cisco Broadband Cable Command Reference Guide on Cisco.com.

show interface cable

To display the current configuration and status of a cable interface, use the show interface cable command in privileged EXEC mode.

show interface cable slot/port [options]

Syntax Description

slot/port

Identifies the Cisco CMTS chassis slot number and downstream port number.

options

Cable-specific options are documented in their own command reference pages in the Cisco Broadband Cable Command Reference Guide on Cisco.com.


Examples

The following example displays show interface cable command output for a CM located in slot 1 and port 0:

Router# show interface cable 5/0/0
 
   
Cable5/0/0 is up, line protocol is up
  Hardware is BCM3210 FPGA, address is 00e0.1e5f.7a60 (bia 00e0.1e5f.7a60)
  Internet address is 1.1.1.3/24
  MTU 1500 bytes, BW 27000 Kbit, DLY 1000 usec, rely 255/255, load 1/255
  Encapsulation, loopback not set, keepalive not set
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 4d07h, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Queuing strategy: fifo
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
10908 packets input, 855000 bytes, 0 no buffer
Received 3699 broadcasts, 0 runts, 0 giants, 0 throttles
3 input errors, 3 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
5412 packets output, 646488 bytes, 0 underruns
0 output errors, 0 collisions, 13082 interface resets
0 output buffer failures, 0 output buffers swapped out
 
   

show interface cable sid

To display the service identifier (SID) for a CM, use the show interface cable sid command in privileged EXEC mode.

show interface cable x/y sid [counters | qos] [verbose]

Syntax Description

x/y

Identifies the Cisco CMTS chassis slot number and downstream port number in slot/port format. Valid values are from 3 to 6.

sid

Service identification number.

counters

Displays the values of the per-SID usage counters. Same as the keyword stats in pre 11.3(6)NA releases.

qos

Displays the QoS characteristics received by each SID.

verbose

Displays detailed information.


Examples

The following sample output from the show interface cable sid command shows the one form of the command:

Router# show int c4/0/0 sid
 
   
Sid  Prim  MAC Address IP Address Type Age    Admin   Sched Sfid
                                                      State   Type
5 0010.7b6b.58c1 10.20.114.34      stat 2d1h36menable  BE     1
6 0010.7bed.9dc9 10.20.114.37      stat 2d1h36menable  BE     13
7 0010.7bed.9dbb 10.20.114.38      stat 2d1h36menable  BE     15
8 0010.7b6b.58bb 10.20.114.112     stat 2d1h34menable  BE     17
9 0010.7b6b.58bb 10.20.114.112     dyna 2d1h34menable  BE     19
 
   

For additional information, examples, command history and related commands, refer to the Cisco Broadband Cable Command Reference Guide on Cisco.com.

show cable modulation-profile

To display modulation profile group information for a Cisco CMTS, use the show cable modulation-profile command in privileged EXEC mode.

show cable modulation-profile [profile] [iuc-code]


Note The show cable modulation-profile command replaces the former show cable burst-profile command.


Syntax Description

profile

(Optional) Profile number. Valid values are from 1 to 8.

iuc-code

(Optional) Internal usage code. Valid options are:

initial—Initial Ranging Burst

long—Long Grant Burst

reqdata—Request/Data Burst

request—Request Burst

short—Short Grant Burst

station—Station Ranging Burst


Examples

The following is sample output from the show cable modulation-profile command:

Router# show cable modulation-profile 1
 
   
Mo 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
 
   
1  request qpsk  64     no   0x0     0x10  0x152   1    8     no   yes     56
1  initial qpsk  128    no   0x5     0x22  0x152   0    48    no   yes     0
1  station qpsk  128    no   0x5     0x22  0x152   0    48    no   yes     0
1  short   qpsk  72     no   0x5     0x4B  0x152   0    8     no   yes     48
 
   

For additional information, examples, command history and related commands, refer to the Cisco Broadband Cable Command Reference Guide on Cisco.com.

Using a Headend CM to Verify Downstream Signals

You can use a Cisco uBR924 cable access modem to verify the downstream signal originating from a Cisco uBR10012 router. Be sure that you configure the Cisco uBR924 according to DOCSIS CM practices.

To verify the downstream signal from a Cisco uBR10012 router using a Cisco uBR924, follow the procedure below:


Step 1 After the Cisco uBR924 is operational and you have an input signal between 0 and +5 dBmV, use the show controller c0 tuner command.

Step 2 Scan the output for the value corresponding to the signal-to-noise (SNR) estimate variable. If this value is at least 35 dB, you have an optimized signal. If the value is less than 34 dB, adjust the upconverter at the cable headend.



Tip The SNR estimate for a CM installed at a headend should be between 35 and 39 dB. Although the exact value displayed varies from CM to CM, values collected on the same CM from measurement to measurement will be consistent. Maximizing SNR optimizes CM reliability and service quality.


Performing Amplitude Averaging

The Cisco uBR10012 router uses an averaging algorithm to determine the optimum power level for a CM with low carrier-to-noise ratio that is making excessive power adjustments—known as flapping. To avoid dropping flapping CMs, the Cisco uBR10012 router averages a configurable number of RNG-REQ messages before it makes power adjustments. By compensating for a potentially unstable return path, the Cisco uBR10012 router maintains connectivity with affected CMs. You can interpret these power adjustments, however, as indicating unstable return path connections.

The show cable flap-list and show cable modem commands are expanded to indicate the paths on which the Cisco uBR10012 router is making power adjustments and the modems that have reached maximum transmit power settings. These conditions indicate unstable paths that should be serviced.

The following example shows the output of the show cable flap-list command:

Router# show cable flap-list
MAC Address     Upstream     Ins   Hit   Miss  CRC   P-Adj Flap  Time
 0010.7bb3.fd19  Cable5/0/0/U1  0     2792  281   0    *45    58    Jul 27 16:54:50
 0010.7bb3.fcfc  Cable5/0/0/U1  0     19    4     0    !43    43    Jul 27 16:55:01
 0010.7bb3.fcdd  Cable5/0/0/U1  0     19    4     0    *3     3     Jul 27 16:55:01
 
   

The asterisk (*) indicates that the CMTS is using the power-adjustment method on this modem. An exclamation point (!) indicates that the modem has reached maximum transmit power.

Output of the show cable modem command appears below:

Router# show cable modem
MAC Address    IP Address      I/F       MAC         Prim RxPwr Timing Num  BPI
                                         State       Sid  (db)  Offset CPEs Enbld
0050.04f9.edf6 10.44.51.49     C7/1/0/U0 online      1   -0.50  3757   0    no
0050.04f9.efa0 10.44.51.48     C7/1/0/U0 online      2   -0.50  3757   0    no
0030.d002.41f5 10.44.51.147    C7/1/0/U0 online      3   -0.25  3829   0    no
0030.d002.4177 10.44.51.106    C7/1/0/U0 online      4   -0.50  3798   0    no
0030.d002.3f03 10.44.51.145    C7/1/0/U0 online      5   0.25   3827   0    no
0050.04f9.ee24 10.44.51.45     C7/1/0/U0 online      6   -1.00  3757   0    no
0030.d002.3efd 10.44.51.143    C7/1/0/U0 online      7   -0.25  3827   0    no
0030.d002.41f7 10.44.51.140    C7/1/0/U0 online      8   0.00   3814   0    no
0050.04f9.eb82 10.44.51.53     C7/1/0/U0 online      9   -0.50  3756   0    no
0050.f112.3327 10.44.51.154    C7/1/0/U0 online      10  0.25   3792   0    no
0030.d002.3f8f 10.44.51.141    C7/1/0/U0 online      11  0.00   3806   0    no
0001.64f9.1fb9 10.44.51.55     C7/1/0/U0 online      12  0.00   4483   0    no
0030.d002.417b 10.44.51.146    C7/1/0/U0 online      13  0.50   3812   0    no
0090.9600.6f7d 10.44.51.73     C7/1/0/U0 online      14  0.00   4071   0    no
0010.9501.ccbb 10.44.51.123    C7/1/0/U0 online      15  0.25   3691   0    no
 
   

The asterisk (*) in the show cable modem command output indicates that the CMTS is using the power adjustment method on this CM. The ! symbol indicates that the CM has reached maximum transmit power.

This section documents the commands pertaining to amplitude averaging:

cable upstream power-adjust noise

cable upstream frequency-adjust averaging

Enabling or Disabling Power Adjustment

To enable the power-adjustment capability, use the cable upstream power-adjust command in interface configuration mode. To disable the power-adjustment capability, use the no form of this command.

cable upstream n power-adjust {threshold [threshold #] | continue [tolerable value] | noise
[% of power adjustment]}

no cable upstream power-adjust

Syntax Description

Syntax
Description

n

Specifies the upstream port number.

threshold #

Specifies the power-adjustment threshold. The threshold range is from 0 to 10 dB. The default is 1 dB.

tolerable value

Determines if the status of the RNG-RSP should be set to CONTINUE or SUCCESS. The range is from 2 to 15 dB. The default is 2 dB.

% of power adjustment

Specifies the percentage of power-adjustment packets required to switch from the regular power-adjustment method to the noise power-adjustment method. Range is from 10 to 100 percent. The default is 30 percent.



Note The threshold default is 1 dB. The tolerable value default is 2 dB. The power adjustment is 30 percent.



Caution Default settings are adequate for system operation. Amplitude averaging is an automatic procedure. In general, Cisco does not recommend that you adjust values. Cisco does recommend, however, that you clean up your cable plant should you encounter flapping CMs.


Note In some instances, you might adjust certain values:

If CMs cannot complete ranging because they have reached maximum power levels, you might try to set the tolerable value CONTINUE field to a larger value than the default of 2 dB. Values larger than 10 dB on "C" versions of cable interface line cards, or 5 dB on FPGA versions, are not recommended.

If the flap list shows CMs with a large number of power adjustments, but the CMs are not detected as noisy, you might try to decrease the percentage for noisy. If you think that too many CMs are unnecessarily detected as noisy, you might try to increase the percentage.


Setting Frequency Threshold to Affect Power Adjustment

To control power-adjustment methods by setting the frequency threshold, use the
cable upstream freq-adj averaging in interface configuration mode. To disable power adjustments, use the no form of this command.

cable upstream n freq-adj averaging % of frequency adjustment

no cable upstream freq-adj averaging

Syntax Description

Syntax
Description

n

Specifies the upstream port number.

averaging

Specifies that a percentage of frequency-adjustment packets is required to change the adjustment method from the regular power-adjustment method to the noise power-adjustment method.

% of frequency adjustment

Specifies the percentage of frequency-adjustment packets required to switch from the regular power-adjustment method to the noise power-adjustment method. Valid range is from 10 to 100 percent.


The following example shows how to change the power-adjustment method when the frequency adjustment packet count reaches 50 percent:

Router(config-if)# cable upstream 0 freq-adj averaging 50	

Setting Downstream Test Signals

This feature provides configuration commands that allow you to create downstream test signals. Both pseudo random bit stream (PRBS) and unmodulated carrier test signals are now supported.

A PRBS test signal is a random data pattern that has been modulated to look like a real data stream. An unmodulated test signal is a continuous sine wave that looks like a carrier wave on the downstream transmission.

See the following sections for the required tasks to create PRBS and unmodulated carrier test signals:

"Configuring Unmodulated Test Signals" section

"Configuring PRBS Test Signals" section

"Verifying Test Signal Output" section

Configuring Unmodulated Test Signals

 
Command
Purpose

Step 1 

Router(config-if# cable downstream 
if-output continuous-wave

Generates an unmodulated continuous wave signal on the downstream channel. The interface is shut down.

Step 2 

Router(config-if# no cable downstream 
if-output 

Stops sending test signals.

Note Remember to reenable the interface to resume normal operations.

Configuring PRBS Test Signals

 
Command
Purpose

Step 1 

Router(config-if# cable downstream 
if-output prbs

Generates a PRBS test signal on the downstream channel. The interface is shut down.

Step 2 

Router(config-if# no cable downstream 
if-output 

Stops sending test signals.

Note Remember to reenable the interface to resume normal operations.

Verifying Test Signal Output

To verify the output of a continuous wave test signal or the output of a PRBS test signal, use a spectrum analyzer on the downstream channel. The downstream carrier is enabled as a default.

The standard mode of operation is modulated signal output and the interface is active. For PRBS and continuous wave output, the selected interface is shut down.

The functioning of the no cable downstream if-output command has not changed. The interface is shut down.

Pinging Unresponsive CMs

Pinging a CM

Ping DOCSIS is a Cisco patent-pending feature that allows a cable system administrator to quickly diagnose the health of a channel between the Cisco uBR10012 router and the cable interface. The technology uses 1/64—the bandwidth of IP ping—and works with CMs that do not have an IP address. This allows cable operators to ping CMs that are unable to complete registration, that have internal bugs, or that are unresponsive due to a crash.

The Ping DOCSIS feature includes a real-time view and plot of requested power adjustments, and a measure of optimal headend reception power. This gives the cable operator the ability to solicit a configurable number of periodic ranging requests from a cable interface.

To ping a specific cable interface to determine if it is online, use the following command in EXEC mode.

Command
Purpose
Router# ping docsis addr

Pings the CM with a specific MAC address or IP address to see if it is online.


Verifying the Ping

The ping docsis command returns a verification from a CM that is pinged:

Queuing 5 MAC-layer station maintenance intervals, timeout is 25 msec:
!!!!!
Success rate is 100 percent (5/5)

Tip If you are having trouble, make sure that you are using a valid MAC or IP address for the cable interface you want to ping.


Using Cable Interface debug Commands

To troubleshoot cable interfaces, use the following debug commands in enable (privileged EXEC) mode.

Command
Purpose
debug cable ?

Displays all debug cable commands that are available.

undebug all

Turns off all debugging information to the console and chooses a more selective debug command.

Note Refer to the debug commands that follow.



Caution The following commands can generate large amounts of output as the number of cable modems grows. On heavily loaded systems with thousands of CMs, these commands can dramatically affect router performance.

debug cable arp

To activate the debugging of Address Resolution Protocol (ARP) requests on the cable interfaces, use the debug cable arp command in privileged EXEC mode. To deactivate debugging of ARP requests, use the no form of this command.

debug cable arp

When this command is activated, all cable ARP request messages are displayed on the Cisco uBR10012 router console.

debug cable error (for MAC Protocol Errors)

To display errors that occur in the cable MAC protocols, use the debug cable error command in privileged EXEC mode. To disable debugging output, use the no form of this command.

debug cable error

no debug cable error

When this command is activated, all cable ARP request messages are displayed on the Cisco uBR10012 router console. When this command is activated, any errors that occur in the cable MAC protocol are displayed on the Cisco uBR10012 router console.

debug cable keyman (for Baseline Privacy Activity)

To activate the debugging of key encryption key (KEK) and traffic encryption key (TEK) BPI key management, use the debug cable keyman command in privileged EXEC mode. To disable debugging output, use the no form of this command.

debug cable keyman

no debug cable keyman

When this command is activated, all activity related to KEK and TEK keys appears on the Cisco uBR10012 router console.

debug cable mac-messages

To activate the debugging of messages generated in the cable MAC that frames and encrypts downstream RF signals, use the debug cable mac-messages command in privileged EXEC mode. To deactivate the debugging of cable MAC messages, use the no form of this command.

debug cable mac-messages

no debug cable mac-messages

When this command is activated, messages generated by the cable MAC are displayed on the Cisco uBR10000 series console.

debug cable map

To display map debugging messages, use the debug cable map command in privileged EXEC mode. Use the no form of this command to disable debugging output.

debug cable map sid [sid-num]

no debug cable map

debug cable phy

To activate the debugging of messages generated in the cable PHY, use the debug cable phy command in privileged EXEC mode. To deactivate the debugging of the cable PHY, use the no form of this command.

debug cable phy

no debug cable phy

Cable PHY is the physical layer where upstream and downstream activity between the Cisco uBR10012 router and the HFC network is controlled. When this command is activated, messages generated in the cable PHY are displayed on the Cisco uBR10012 router console.

debug cable privacy (for Baseline Privacy)

To activate the debugging of baseline privacy, use the debug cable privacy command in privileged EXEC mode. To disable debugging output, use the no form of this command.

debug cable privacy

no debug cable privacy

debug cable qos

To activate the debugging of QoS, use the debug cable qos command in privileged EXEC mode. To deactivate debugging of QoS, use the no form of this command.

debug cable qos

no debug cable qos

When this command is activated, messages related to QoS parameters are displayed on the Cisco uBR10012 router console.

debug cable range (for Ranging Messages)

To activate the debugging of ranging messages from cable interfaces on the HFC network, use the debug cable range command in privileged EXEC mode. To deactivate debugging of cable interface ranging, use the no form of this command.

debug cable range

no debug cable range

When this command is activated, ranging messages generated when cable interfaces request or change their upstream frequencies are displayed on the Cisco uBR10012 router console.

debug cable receive (for Upstream Messages)

To activate the debugging of upstream messages from cable interfaces, use the debug cable receive command in privileged EXEC mode. To deactivate debugging of upstream messages, use the no form of this command.

debug cable receive

no debug cable receive

When this command is activated, any messages generated by cable interfaces and sent to the Cisco uBR10012 router are displayed on the router console.

debug cable reg (for Modem Registration Requests)

To activate the debugging of registration requests from cable interfaces on the HFC network, use the debug cable reg command in privileged EXEC mode. To deactivate debugging of cable registration, use the no form of this command.

debug cable reg

no debug cable reg

When this command is activated, messages generated by cable interfaces as they make requests to connect to the network are displayed on the Cisco uBR10012 router console.

debug cable reset (for Reset Messages)

To activate the debugging of reset messages from cable interfaces on the HFC network, use the debug cable reset command in privileged EXEC mode. To deactivate debugging of cable reset messages, use the no form of this command.

debug cable reset

no debug cable reset

When this command is activated, reset messages generated by cable interfaces are displayed on the Cisco uBR10012 router console.

debug cable specmgmt (for Spectrum Management)

To activate the debugging of spectrum management (frequency agility) on the HFC network, use the debug cable specmgmt command in privileged EXEC mode. To deactivate debugging of cable spectrum management, use the no form of this command.

debug cable specmgmt

no debug cable specmgmt

When this command is activated, messages generated because of spectrum group activity are displayed on the Cisco uBR10012 router console. Spectrum group activity can be additions or changes to spectrum groups, or frequency and power level changes controlled by spectrum groups.

debug cable startalloc (for Channel Allocations)

To activate the debugging of channel allocations on the HFC network, use the debug cable startalloc command in privileged EXEC mode. To deactivate debugging of cable channel allocations, use the no form of this command.

debug cable startalloc

no debug cable startalloc

When this command is activated, messages generated when channels are allocated to cable interfaces on the HFC network are displayed on the Cisco uBR10012 router console.

debug cable transmit (for CMTS Transmissions)

To activate the debugging of transmissions from the Cisco uBR10012 router across the HFC network, use the debug cable transmit command in privileged EXEC mode. To deactivate debugging of cable transmissions, use the no form of this command.

debug cable transmit

no debug cable transmit

When this command is activated, messages generated at the headend are displayed on the 
Cisco uBR10012 router console. 

debug cable ucc (for Upstream Channel Change Messages)

To activate the debugging of upstream channel change (UCC) messages generated when cable interfaces request or are assigned a new channel, use the debug cable ucc command in privileged EXEC mode. To deactivate debugging of cable upstream channel changes, use the no form of this command.

debug cable ucc

no debug cable ucc

When this command is activated, messages related to upstream channel changes are displayed on the Cisco uBR10012 router console.

debug cable ucd (for Upstream Channel Description Messages)

To activate the debugging of upstream channel descriptor (UCD) messages, use the debug cable ucd command in privileged EXEC mode. To deactivate debugging of cable upstream channel descriptor, use the no form of this command:

debug cable ucd

no debug cable ucd

UCD messages contain information about upstream channel characteristics and are sent to the cable modems on the HFC network. CMs that are configured to use enhanced upstream channels use these UCD messages to identify and select an enhanced upstream channel to use. When this command is activated, messages related to upstream channel descriptors are displayed on the Cisco uBR10012 router console.