Cisco Systems uBR7200 Series Performing Amplitude Averaging, Enable or Disable Power Adjustment

Page 45

Chapter 4 Troubleshooting the System

Performing Amplitude Averaging

Performing Amplitude Averaging

The Cisco uBR7200 series uses an averaging algorithm to determine the optimum power level for a cable modem with low carrier-to-noise ratio that is making excessive power adjustments—known as flapping. To avoid dropping flapping cable modems, the Cisco uBR7200 series universal broadband router averages a configurable number of RNG-REQ messages before it makes power adjustments. By compensating for a potentially unstable return path, the Cisco uBR7200 series router maintains connectivity with affected cable modems. You can interpret these power adjustments, however, as indicating unstable return path connections.

The show cable flap-listand show cable modem commands are expanded to indicate which paths the Cisco uBR7200 series is making power adjustments and which modems 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-listcommand:

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

The * symbol indicates that the CMTS is using the power adjustment method on this modem. The ! symbol indicates that the modem has reached maximum transmit power.

Output of the show cable modem command appears below:

router# show

cable modem

 

 

 

 

 

 

Interface

Prim

Online

Timing Rec

QoS

CPE IP address

MAC address

 

Sid

State

Offset Power

 

 

 

 

Cable3/0/U0

1

online

2257

0.00

3

0

10.30.128.142

0090.8330.0217

Cable3/0/U0

2

online

2262

*-0.50

3

0

10.30.128.145

0090.8330.020f

Cable3/0/U0

3

online

2260

0.25

3

0

10.30.128.146

0090.8330.0211

Cable3/0/U0

4

online

2256

*0.75

3

0

10.30.128.143

0090.8330.0216

Cable3/0/U0

5

online

2265

*0.50

3

0

10.30.128.140

0090.8330.0214

Cable3/0/U0

6

online

2256

0.00

3

0

10.30.128.141

0090.8330.0215

Cable3/0/U0

7

online

4138

!-1.00

3

1

10.30.128.182

0050.7366.124d

Cable3/0/U0

8

online

4142

!-3.25

3

1

10.30.128.164

0050.7366.1245

Cable3/0/U0

9

online

4141

!-3.00

3

1

10.30.128.185

0050.7366.17e3

Cable3/0/U0

10

online

4142

!-2.75

3

0

10.30.128.181

0050.7366.17ab

Cable3/0/U0

11

online

4142

!-3.25

3

1

10.30.128.169

0050.7366.17ef

Similar to the show cable flap-listdisplay, the * symbol in the show cable modem 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

Enable or Disable Power Adjustment

To enable or disable the power adjustment capability, use the following commands:

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

no cable upstream power-adjust

Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide

 

78-5897-01

4-45

 

 

 

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Contents Troubleshooting the System Managing Cable Modems on the HFC Network Configure Sync Message IntervalVerify Cable Modem Authentication Activate Cable Modem AuthenticationActivate Cable Modem Upstream Address Verification Verify Sync Message IntervalCMTS01config-if#cable source-verify dhcp CMTS01config-if#no cable source-verifyVerify Cable Modem Upstream Address Verification CMTS01config-if#cable insertion-interval max CMTS01config-if#no cable insertion-intervalCMTS01config-if#cable insertion-interval AutomaticConfigure Per Modem Filters Configure access lists to be specified on a Configure Cable Modem Registration Timeout Clear Cable Modem ResetCMTS01config-if#cable registration-timeout n Clear Cable Modem Counters Verify Clear Cable Modem ResetConfigure Downstream Rate Limiting and Shaping Configure Traffic ShapingConfigure Upstream Rate Limiting and Shaping Verify Clear Cable Modem CountersBlind Strategies and Time Scheduled Combined CMTS01config-if#nocable upstream n1 rate-limitToken-bucket CMTS01# show interface c3/0 sid 1 countersGuided Frequency Hop Field Description Sample outputShow Cable Hop Command Spectrum Management Debug and Test Commands14 Show Cable Hop Parameter Descriptions Polling Cable Modems Debug and Test CommandsConfigure Remote Modem Monitoring Enable SnmpAllows you to configure access Verifying Remote Query InformationUnderstanding Show Command Responses General Show CommandsMonitoring and Maintaining Remote Querying Show Cable Modem See the sample command output below Page SID Show Cable Modem Maintenance Cable modem cable 3/0 upstream 0 unregisteredCable modem cable 3/0 upstream 0 offline Show Interface Cable UBR7200#show cable modem maintenanceMTU CRC Router# show interface cable 6/0 downstream Field Description18 Show Interface Cable Upstream Command Field Descriptions ATP Enhanced Show Interface Upstream Output Cable slot 3, port Show Interface Cable SIDShow Router# show interface c3/0 sid counters verboseRouter# show interface c3/0 sid connectivity ConnectivityRouter# show interface c3/0 sid 1 counters Troubleshooting Using Cable Flap Lists Show Cable QoS ProfileUBR7200#show cable qos profile Page Page UBR7200#show cable flap Display the Flap ListMAC ID Statistic DescriptionPlant troubleshooting. The CRC counter indicates Troubleshoot with the Flap List Set Cable Flap List Insertion Time Set Cable Flap List AgingVerify Cable Flap List Aging Verify Cable Flap List Insertion TimeSet Cable Flap List Power Adjustment Threshold Verify Cable Flap List Power Adjustment ThresholdSet Cable Flap List Miss Threshold Clear Cable Flap List Set Cable Flap List SizeVerify Cable Flap List Miss Threshold Verify Cable Flap List SizeCustomize Other Flap List Values and Related Commands Performing Amplitude Averaging Enable or Disable Power AdjustmentSyntax Valid Values Set Frequency Threshold to Affect Power AdjustmentSetting Downstream Test Signals Configure Unmodulated Test SignalsStep Command Purpose Verify Test Signal Output Configure Prbs Test SignalsStep Command Pinging Unresponsive Cable ModemsUsing Cable Interface Debug Commands Verify the PingDebug Cable ARP Requests Debug Environmental Monitor Messages Debug Cable MAC Protocol ErrorsActivate Debug of Baseline Privacy Debug Baseline Privacy ActivityDebug Cable Modems Debug Cable MapsDebug Cable PHY Messages Activate QoS DebugDebug Cable Modem Ranging Messages Debug Cable Modem Reset MessagesDebug Upstream Messages Debug Cable Modem Registration RequestsDebug Channel Allocations Debug Spectrum ManagementDebug Cmts Transmissions Debug Upstream Channel Change UCC MessagesDebug Upstream Channel Description UCD Messages Managing the Cisco uBR7246 VXR Clock CardClear Clock Counters Show diag Show frame-clocks Show tech support Show versionSet Midplane TDM Clock as Primary Reference Force Alternate ClockDisplay Clock Values Cable clock force primary secondary no cable clock forceShow Clock Hardware Information and Register Values Show Clock Diagnostic InformationRouter# show cable clock Show controllers clock-reference33 describes the fields shown in the show diag display Show Clock Frames Show General InformationRouter# show frame-clocks
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