Cisco Systems uBR7200 manual Troubleshooting Using Cable Flap Lists, Setting Cable Flap List Aging

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Configuring Headend Broadband Access Router Features

Troubleshooting Using Cable Flap Lists

Troubleshooting Using Cable Flap Lists

A cable flap list is a table maintained by the Cisco uBR7200 series for every cable modem (active or not active) that is having difficulties communicating with the headend. Flapping refers to the rapid disconnecting and reconnecting of a cable modem. The flap list contains cable modem MAC addresses and logs the time of the most recent activity. You can configure the size, recording duration, and entry thresholds for the flap list.

The following tips and scenarios allow you to use the flap list in the most effective way:

If a subscriber cable modem shows substantial flap list activity, it is having communication problems.

If a subscriber’s cable modem shows little or no flap list activity, it is communicating reliably; the problem is probably in the subscriber computer equipment or in the connection to the cable modem.

The top 10 percent most active cable modems in the flap list are most likely to have difficulties communicating with the headend.

Cable modems with more than 50 power adjustments per day have a suspect upstream path.

Cable modems with approximately the same number of hits and misses and with many insertions have a suspect downstream path (for example, low level into the cable modem).

All cable modems incrementing the insertion at the same time indicates a provisioning server failure.

Cable modems with a high number of CRC errors have unstable upstream paths or in-home wiring problems.

Correlating cable modems on the same physical upstream port with similar flap list statistics can quickly isolate outside plant problems to a particular node or geography.

Monitoring the flap list cannot affect cable modem communications.

The flap list should be “dumped” to a database computer and cleared at least once a day.

Important upstream performance data can be obtained by tracking flap list trend data.

Important installation quality control and performance data is directly available from the flap list.

Setting Cable Flap List Aging

You can specify the number of days to record and retain flapping activity on cable modems currently in the flap list table. This value is known as the age of the flap list. The valid range is from 1 to 60 days.

To set the age of the flap list, use the following command in global configuration mode:

Command

Purpose

 

 

CMTS01(config)# cable flap-list aging days

Specifies the number of days to record and retain flapping

 

activity for the cable modems connected to this Cisco uBR7200

 

series router.

 

 

Cisco IOS Multiservice Applications Configuration Guide

MC-603

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Contents MC-519 Configuring Headend Broadband Access Router FeaturesMC-520 Headend OverviewTopology of a Typical Broadband Network Voice over IP Services MC-523 Telco ReturnTOD MC-524Service Class Profiles QoS FeaturesMultiple Service IDs MC-525QoS Profile Enforcement TAG/NetFlow SwitchingMC-526 Netflow Switching Tag SwitchingMC-527 Weighted Random Early Detection Security FeaturesWeighted Fair Queueing Committed Access Rate CARDocsis Baseline Privacy Cable Modem and Multicast Authentication Using RadiusUpstream Address Verification MC-529Operations and Provisioning Features Traffic Shaping FeaturesDynamic Ranging MC-530Burst Profile Configuration Downstream Channel ID ConfigurationDownstream Frequency Override CPE LimitationSpectrum Management MC-533 Headend Broadband Access Router Configuration PrerequisitesMC-534 Headend Broadband Access Router Configuration TasksCMTS01# configure terminal Configuring the Downstream Cable InterfaceCMTS01config# interface cable 6/0 Activating the Downstream CarrierTroubleshooting Tips Setting the Downstream Center FrequencyVerifying the Downstream Carrier MC-536Verifying the Downstream Center Frequency CMTS01config-if#cable downstream frequencyMC-537 Setting the Downstream Mpeg Framing Format Annex B Setting the Downstream Channel IDVerifying the Downstream Channel ID MC-538Verifying the Downstream Mpeg Framing Format Setting the Downstream ModulationVerifying the Downstream Modulation MC-539CMTS01config-if#cable downstream interleave-depth Setting the Downstream Interleave DepthVerifying the Downstream Interleave Depth MC-540Verifying the Downstream Helper Address Setting the Downstream Helper AddressMC-541 MC-542 Setting Downstream Rate LimitingVerifying Downstream Rate Limiting Configuring the Upstream Cable InterfaceMC-543 MC-544 Setting the Upstream FrequencyMC-545 Verifying the Upstream FrequencyCMTS01# show controllers cable 6/0 u0 Verifying Upstream Channel Width Setting the Upstream Channel WidthMC-546 Channel-width widthMC-547 Setting the Upstream Input Power LevelActivating Upstream Admission Control Verifying the Upstream Input Power LevelVerifying Upstream Admission Control MC-548MC-549 Activating Upstream FECSpecifying Upstream Minislot Size Router# more systemrunning-configVerifying Upstream FEC MC-550Verifying Upstream Minislot Size Activating the Upstream ScramblerMC-551 CMTS01# more systemrunning-config CMTS01config-if#cable upstream usport scramblerVerifying the Upstream Scrambler MC-552Activating Upstream Rate Limiting Activating Upstream Differential EncodingVerifying Upstream Differential Encoding MC-553Verifying Upstream Rate Limiting CMTS01config-if#no cable upstream usport rate-limitMC-554 Frequency-adjust averaging percentage Activating Upstream Frequency AdjustmentMC-555 Verifying Upstream Frequency Adjustment Activating Upstream Power AdjustmentMC-556 Verifying Upstream Power Adjustment Activating Upstream Timing AdjustmentMC-557 Continue secondsActivating the Upstream Ports Verifying Upstream Timing AdjustmentMC-558 Verifying the Upstream Ports Setting Upstream Backoff ValuesMC-559 MC-560 CMTS01config-if#cable upstream usport rangeData-backoff start end Data-backoff automaticVerifying Upstream Data Backoff Automatic Configuring and Activating Baseline PrivacyMC-561 CMTS01config-if#cable privacy kek grace-time Configuring KEK PrivacyMC-562 Verifying KEK Privacy Configuring TEK PrivacyVerifying TEK Privacy MC-563Activating Baseline Privacy Configuring and Activating Frequency AgilityVerifying Baseline Privacy MC-564MC-565 Combiner GroupsMC-566 Frequency Management PolicyMC-567 Determining the Upstream Ports Assigned to a Combiner GroupCreating Spectrum Groups Configuring and Activating Spectrum GroupsVerifying Spectrum Groups MC-568MC-569 Command PurposeMC-570 Verifying Frequency Hopping Verifying Spectrum Group ConfigurationMC-571 MC-572 Configuring Spectrum Group CharacteristicsCMTS01config# cable spectrum-group groupnum hop Verifying Spectrum Group CharacteristicsMC-573 Threshold percentAssigning the Spectrum Group and the Upstream Ports Activating IP Address Resolution ProtocolActivating Cable ARP Requests Verifying Spectrum Group and Upstream Port AssignmentsVerifying ARP Requests Activating Host-to-Host Communication Proxy ARPMC-575 Activating Cable Proxy ARP Requests Configuring Dhcp OptionsActivating Cable Relay Agent Verifying Cable Proxy ARP RequestsVerifying Dhcp giaddr Activation Activating Dhcp giaddrMC-577 Setting Optional IP Parameters Setting Service OptionsConfiguring ToD Service Verifying ToD ServiceActivating IP Broadcast Echo Activating IP Multicast EchoVerifying IP Multicast Echo MC-579Configuring Cable Modulation Profiles Configuring Cable ProfilesVerifying IP Broadcast Echo MC-580MC-581 Number profileVerifying Cable Modulation Profiles Configuring QoS ProfilesMC-582 MC-583 Verifying QoS ProfilesEnforcing a QoS Profile Assignment Setting QoS PermissionVerifying QoS Permission MC-584Verifying a QoS Profile Assignment Managing Cable Modems on the HFC NetworkMC-585 Configuring Telco Return Configuring Sync Message IntervalActivating Cable Modem Authentication Verifying Sync Message IntervalActivating Cable Modem Upstream Address Verification Verifying Cable Modem AuthenticationMC-587 Activating Cable Modem Insertion Interval CMTS01config-if#cable source-verify dhcpVerifying Cable Modem Upstream Address Verification MC-588Verifying Cable Modem Insertion Interval CMTS01config-if#cable insertion-interval automaticMC-589 Verifying the Maximum Number of Hosts Configuring Cable Modem Registration TimeoutMC-590 Verifying Registration Timeout Clearing and Resetting Cable ModemsMC-591 Clearing Cable Modem Counters Verifying Cable Modem Clearing and ResettingMC-592 Verifying that Cable Modem Counters are Cleared Using Ping DocsisVerifying Ping Docsis MC-593MC-594 Spectrum Management Configuration ExampleMC-595 Virtual Private Network Configuration ExampleMC-596 MC-597 Ip http server Ip http authentication local No cdp runMC-598 VoIP Configuration ExampleIp subnet-zero No ip domain-lookup MC-599MC-600 Telco Return Configuration ExampleMC-601 Cable telco-return enableCable Modem all reset QoS Profile Enforcement Configuration ExampleMC-602 Cable RegSetting Cable Flap List Aging Troubleshooting Using Cable Flap ListsCMTS01config# cable flap-list aging days MC-603Setting Cable Flap List Power Adjustment Threshold Setting Cable Flap List Insertion TimeVerifying Cable Flap List Aging Verifying Cable Flap List Insertion TimeVerifying Cable Flap List Power Adjustment Threshold Setting Cable Flap List Miss ThresholdCMTS01config# cable flap-list miss-threshold misses Verifying Cable Flap List Miss ThresholdClearing Cable Flap List Setting Cable Flap List SizeVerifying Cable Flap List Size MC-606
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