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Cisco UBR904 - Router - EN Troubleshooting Tips

Cisco UBR904 - Router - EN Troubleshooting Tips

Troubleshooting guide
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Download this manual See also: Installation, Installation Manual
Troubleshooting Tips for the
Cisco uBR904 Cable Modem
The following sections are provided:
•
Feature Summary on page 1
•
Platforms on page 3
•
Supported MIBs and RFCs on page 3
•
CMTS to Cable Modem Network Topology on page 4
•
Troubleshooting Steps on page 5
•
Command Reference on page 16
•
Debug Commands on page 49
•
What to do Next on page 61

Feature Summary

This document describes the set of Cisco IOS troubleshooting commands that may be used by
multiple service operators (MSOs) to verify communication between a Cisco uBR904 cable modem
and other peripheral devices installed in the HFC network such as the headend Cisco uBR7246
router, a DHCP server, and a TFTP server.
Note
Messages, viewable online at
www.cisco.com/univercd/cc/td/doc/product/cable/cab_modm/ubcmerrs.pdf .
Benefits
The uBR904 troubleshooting system provides the following benefits:
•
A MAC-layer system log file exists which provides a snapshot of detailed reasons why an
interface might reset, along with all the negotiations that occurred between the uBR904 cable
modem and the CMTS (a Cisco uBR7246 positioned at the headend). Over 220 possible
description fields exist in this log, which is displayed using the show controllers cable-modem
0 mac log command from privileged EXEC mode.
•
Debug does not need to be turned on to troubleshoot a uBR904 cable modem.
For an explanation of error messages displayed by the uBR904, see Cisco Cable CPE Error
Troubleshooting Tips for the Cisco uBR904 Cable Modem 1

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Summary of Contents for Cisco UBR904 - Router - EN

  • Page 1: Feature Summary

    What to do Next on page 61 Feature Summary This document describes the set of Cisco IOS troubleshooting commands that may be used by multiple service operators (MSOs) to verify communication between a Cisco uBR904 cable modem and other peripheral devices installed in the HFC network such as the headend Cisco uBR7246 router, a DHCP server, and a TFTP server.

  • Page 2: List Of Terms

    The progression of normal data-over-cable communication events is clearly explained, simplifying the resolution of faulty system connections. • A cable technician can remotely telnet into a Cisco uBR904 cable modem, which could be installed in a customer’s home, and perform simple diagnostic tasks. List of Terms CATV—Originally stood for Community Antenna Television.
  • Page 3 Subscriber Unit (SU)—An alternate term for cable modem. See cable modem. Upstream—The set of frequencies used to send data from a subscriber to the headend. Platforms The uBR904 cable modem is a standalone device; it works in conjunction with the Cisco uBR7246 universal broadband router. Prerequisites See the companion to this document, “Bridging and Routing Features for the Cisco uBR904 Cable Modem”...
  • Page 4 MSD: Maintenance Service Organization, Cable companies Analog TV Upconvertor DS-RF 54-860 Mhz Digital TV Fiber Transceiver 80 km 1000 ft Fiber node (Telephone pole, underground box) Drop box Distribution amplifier amplifier Cisco u BR904 cable modem Cisco IOS Release 12.0(3)T...
  • Page 5 (Optional) Step 5—Use Additional Troubleshooting Commands Step 1—Understand How Basic Initialization Works Before you troubleshoot a Cisco uBR904 cable modem, you should be familiar with the cable modem initialization process. See Figure 2 and Table 1. Understanding this flowchart and sequence of events will help you determine where and why connections fail.
  • Page 6 Upstream Transfer parameter complete acquired Register with Start the Cisco Ranging uBR7246 Ranging and Registration auto adjust complete completed Establish Baseline privacy connectivety initialization Baseline privacy complete initialized Establish Operational time of Time of day established Cisco IOS Release 12.0(3)T...
  • Page 7 Telnet to the IP address assigned to the cable interface or Ethernet interface. If the interface is not up, you need to access the Cisco IOS software via the RJ-45 console port, which is a physical port on the back of the cable modem.
  • Page 8 Following is an example of what the MAC log file looks like when the cable modem interface successfully comes up and registers with the CMTS. The output you see is directly related to the messages that are exchanged between the cable modem and the headend Cisco uBR7246. uBR904# show controllers cable-modem 0 mac log 508144.340 CMAC_LOG_DRIVER_INIT_IDB_RESET...
  • Page 9 508177.164 CMAC_LOG_STATE_CHANGE configuration_file_state 508177.166 CMAC_LOG_LOADING_CONFIG_FILE platinum.cm 508178.280 CMAC_LOG_CONFIG_FILE_PROCESS_COMPLETE 508178.300 CMAC_LOG_STATE_CHANGE registration_state 508178.302 CMAC_LOG_REG_REQ_MSG_QUEUED 508178.306 CMAC_LOG_REG_REQ_TRANSMITTED 508178.310 CMAC_LOG_REG_RSP_MSG_RCVD 508178.312 CMAC_LOG_COS_ASSIGNED_SID 508178.314 CMAC_LOG_RNG_REQ_QUEUED 508178.316 CMAC_LOG_REGISTRATION_OK 508178.318 CMAC_LOG_STATE_CHANGE establish_privacy_state 508178.320 CMAC_LOG_NO_PRIVACY 508178.322 CMAC_LOG_STATE_CHANGE maintenance_state Troubleshooting Tips for the Cisco uBR904 Cable Modem 9...
  • Page 10 The MAC layer informs the cable modem’s drivers that it needs to reset. This is the first event that happens after the modem powers up and begins initialization. The fields LINK_DOWN LINK_UP similar to the shut and no shut conditions on a standard Cisco interface. uBR904# show controllers cable-modem 0 mac log 528302.040 CMAC_LOG_LINK_DOWN 528302.042 CMAC_LOG_RESET_FROM_DRIVER 528302.044 CMAC_LOG_STATE_CHANGE...
  • Page 11 Some CATV systems use alternative frequency plans such as the IRC (Incrementally Related Carrier) and HRC (Harmonically Related Carrier) plans. Most of the IRC channel slots overlap the EIA plan. The HRC plan is not supported by Cisco’s cable modems since so few cable plants are using this plan.
  • Page 12 Troubleshooting Steps Event 3—Obtain Upstream Parameters The cable modem waits for an upstream channel descriptor (UCD) message from the headend Cisco uBR7246. This is done to retrieve transmission parameters for the upstream channel. 508146.124 CMAC_LOG_STATE_CHANGE wait_ucd_state 508147.554 CMAC_LOG_UCD_MSG_RCVD 508147.558 CMAC_LOG_UCD_NEW_US_FREQUENCY 20000000 508147.558 CMAC_LOG_SLOT_SIZE_CHANGED...
  • Page 13 508176.996 CMAC_LOG_DHCP_COMPLETE Event 6 Establish the Time of Day — The Cisco uBR904 cable modem accesses the Time of Day server for the current date and time, which is used to create time stamps for logged events. The field indicates CMAC_LOG_TOD_COMPLETE a successful time of day sequence.

  • Page 14: Perform Registration

    Perform Registration — The cable modem registers with the headend Cisco uBR7246. After the cable modem is initialized, authenticated, and configured, the cable modem is authorized to forward traffic into the cable network. A successful registration is indicated by the field CMAC_LOG_REGISTRATION_OK 508178.300 CMAC_LOG_STATE_CHANGE...
  • Page 15 Debugs cable modem interface interrupts. debug cable-modem mac verbose messages Displays and debugs the MAC-layer log entries in real time. debug cable-modem map Debugs map message processing information. Troubleshooting Tips for the Cisco uBR904 Cable Modem 15...

  • Page 16: Command Reference

    Command Reference This section describees new and changed commands in Cisco IOS Release 12.0(3)T for troubleshooting the Cisco uBR904 cable modem. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command references. • show controllers cable-modem •...

  • Page 17: Syntax Description

    Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. The show controllers cable-modem display begins with information from the first few registers of the Broadcom BCM3220 chip. Next is buffer information for the receive, receive MAC message, buffer descriptor, and packet descriptor rings.
  • Page 18 DS mac msg overruns = 0, DS data overruns = 0 Qualified maps = 348, Qualified syncs = 73 CRC fails = 0, HDR chk fails = 0 Data pdus = 0, Mac msgs = 423 Valid hdrs = 423 BCM3220 Registers: downstream dma: ds_data_bd_base=0x001D40, ds_mac_bd_base=0x001E80 Cisco IOS Release 12.0(3)T...
  • Page 19 IP address of the TFTP server at the headend. TOD server IP address of the time-of-day server at the headend. Security server IP address of the security server at the headend. Troubleshooting Tips for the Cisco uBR904 Cable Modem 19...
  • Page 20 16-bit Header Check Sequence (HCS) field that ensures the integrity of the MAC header even in a collision environment. Data pdus Total number of data PDUs (protocol data units) of all types received by the uBR904. Cisco IOS Release 12.0(3)T...

  • Page 21: Related Commands

    Hexadecimal values of the pending IRQ interrupt and IRQ mask. Related Commands show controllers cable-modem bpkm show controllers cable-modem des show controllers cable-modem filters show controllers cable-modem lookup-table show controllers cable-modem mac show controllers cable-modem phy show controllers cable-modem tuner Troubleshooting Tips for the Cisco uBR904 Cable Modem 21...
  • Page 22 Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Examples The following output is displayed when the headend CMTS does not have baseline privacy enabled: uBR904# show controllers cable-modem 0 bpkm...
  • Page 23 The current state of the traffic encryption key state machine for the specified SID. Related Commands show controllers cable-modem show controllers cable-modem des show controllers cable-modem filters show controllers cable-modem lookup-table show controllers cable-modem mac show controllers cable-modem phy show controllers cable-modem tuner Troubleshooting Tips for the Cisco uBR904 Cable Modem 23...
  • Page 24 Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Examples DES engine registers are displayed in the following example: uBR904# show controllers cable-modem 0 des downstream des:...
  • Page 25 0x24 means that the upstream is configured to enable decryption and to use CBC mode Related Commands show controllers cable-modem show controllers cable-modem bpkm show controllers cable-modem filters show controllers cable-modem lookup-table show controllers cable-modem mac show controllers cable-modem phy show controllers cable-modem tuner Troubleshooting Tips for the Cisco uBR904 Cable Modem 25...
  • Page 26 Controller number inside the cable modem. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Some of the filtering parameters are MAC hardware addresses, Service IDs (SIDs), and upstream channel IDs. Examples MAC and SID filter information is displayed in the following example:...
  • Page 27 Number of ranging requests that can be held in the first-in-first-out buffer. Related Commands show controllers cable-modem show controllers cable-modem bpkm show controllers cable-modem des show controllers cable-modem lookup-table show controllers cable-modem mac show controllers cable-modem phy show controllers cable-modem tuner Troubleshooting Tips for the Cisco uBR904 Cable Modem 27...
  • Page 28 Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. This command shows the details of the lookup table. The driver uses this table to convert the size of a packet that the cable modem wants to transmit into a bandwidth request to the CMTS in mini-slots.
  • Page 29 68 68 68 68 68 68 68 68 68 68 68 68 68 68 68 68 570: 68 68 68 68 68 68 68 68 68 68 68 68 68 68 68 68 Troubleshooting Tips for the Cisco uBR904 Cable Modem 29...
  • Page 30 0DC0 0DC0 0DC0 0DC0 0E9C 0E9C 0E9C 0E9C Related Commands show controllers cable-modem show controllers cable-modem bpkm show controllers cable-modem des show controllers cable-modem filters show controllers cable-modem mac show controllers cable-modem phy show controllers cable-modem tuner Cisco IOS Release 12.0(3)T...
  • Page 31 Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. MAC log messages are written to a circular log file even when debugging is not turned on. These messages include timestamps, events, and information pertinent to these events. Enter the show controllers cable-modem mac log command to view MAC log messages.
  • Page 32 7 01:43:13: 528315.948 CMAC_LOG_RNG_REQ_QUEUED *Mar 7 01:43:14: 528316.942 CMAC_LOG_RNG_REQ_TRANSMITTED *Mar 7 01:43:14: 528316.944 CMAC_LOG_RNG_RSP_MSG_RCVD *Mar 7 01:43:14: 528316.946 CMAC_LOG_ADJUST_TX_POWER *Mar 7 01:43:14: 528316.950 CMAC_LOG_POWER_LEVEL_IS 30.0 dBmV (commanded) *Mar 7 01:43:14: 528316.952 CMAC_LOG_RANGING_CONTINUE *Mar 7 01:43:15: 528317.956 CMAC_LOG_RNG_REQ_TRANSMITTED Cisco IOS Release 12.0(3)T...
  • Page 33 (from 8 dBmv to 61 dBmv). The cable modem tried to communicate with the CMTS 16 times without success, after which it reset the cable interface to try to find a better downstream frequency. Troubleshooting Tips for the Cisco uBR904 Cable Modem 33...
  • Page 34 The following example indicates that an event in the cable interface driver caused the interface to reset. This often occurs because a shut or clear command is currently being issued on the interface. uBR904# show controllers cable-modem 0 mac resets 527986.444 CMAC_LOG_RESET_FROM_DRIVER 528302.042 CMAC_LOG_RESET_FROM_DRIVER 528346.600 CMAC_LOG_RESET_FROM_DRIVER 528444.494 CMAC_LOG_RESET_FROM_DRIVER Cisco IOS Release 12.0(3)T...
  • Page 35 The Network Access parameter was missing from the CMAC_LOG_RESET_NET_ACCESS_MISSING DOCSIS configuration file. CMAC_LOG_RESET_FAILED_WRITE_ACCESS_CONTROL The cable modem was unable to set the Write Access Control for an SNMP parameter, as specified by the DOCSIS configuration file. Troubleshooting Tips for the Cisco uBR904 Cable Modem 35...
  • Page 36 10 pak=0x82DEA7C buf=0x224DE2 status=0x80 pak_size=0 11 pak=0x82DE884 buf=0x2246DA status=0x80 pak_size=0 12 pak=0x82DE68C buf=0x223FD2 status=0x80 pak_size=0 13 pak=0x82DE494 buf=0x2238CA status=0x80 pak_size=0 14 pak=0x82DE29C buf=0x2231C2 status=0x80 pak_size=0 15 pak=0x82DE0A4 buf=0x222ABA status=0x80 pak_size=0 16 pak=0x82DDEAC buf=0x2223B2 status=0x80 pak_size=0 17 pak=0x82DDCB4 buf=0x221CAA status=0x80 pak_size=0 Cisco IOS Release 12.0(3)T...
  • Page 37 Qualified maps = 0, Qualified syncs = 0 CRC fails = 0, HDR chk fails = 0 Data pdus = 0, Mac msgs = 0 Valid hdrs = 0 BCM3220 Registers: downstream dma: ds_data_bd_base=0x001D40, ds_mac_bd_base=0x001E80 Troubleshooting Tips for the Cisco uBR904 Cable Modem 37...
  • Page 38 Number of times the DMA controller had downstream data and there were no free data PDU buffer descriptors to accept the data. Qualified maps Number of valid MAP messages received by the cable modem. Qualified syncs Number of times the cable modem received synchronization with the downstream channel. Cisco IOS Release 12.0(3)T...
  • Page 39 Number of valid MAC headers received by the cable interface. Below the MIB statistics in the display, the BCM3220 registers section shows the DMA locations of the indicated processing routines of the Broadcom 3220 MAC chip within the Cisco uBR904. Example 5 The show controllers cable-modem mac state command summarizes the state of the cable MAC layer.
  • Page 40 FEC Codeword Info Bytes: Scrambler Seed: Maximum Burst Size: Guard Time Size: Last Codeword Length: Scrambler on/off: Burst Descriptor Interval Usage Code: Modulation Type: Differential Encoding: Preamble Length: Preamble Value Offset: FEC Error Correction: FEC Codeword Info Bytes: Cisco IOS Release 12.0(3)T...
  • Page 41 Number of times the uBR904 received invalid registration response messages. T1 Timeouts Number of timeouts caused by the uBR904 not receiving a valid upstream channel descriptor (UCD) from the CMTS within the specified time. Troubleshooting Tips for the Cisco uBR904 Cable Modem 41...
  • Page 42 If the value of this count in a sebsequent upstream channel descriptor (UCD) remains the same, the cable modem can quickly decide that the remaining fields have not changed, and may be able to disregard the remainder of the message. Preamble Pattern Byte pattern used for the preamble. Cisco IOS Release 12.0(3)T...
  • Page 43 The number of seconds the TEK state machine waits for a replacement key for this SID after the TEK grace timer has expired and the request for a replacement key has been made. Troubleshooting Tips for the Cisco uBR904 Cable Modem 43...

  • Page 44: Related Commands

    Correction received from the DHCP server to synchronize the cable modem time clock with the CMTS. Related Commands show controllers cable-modem show controllers cable-modem bpkm show controllers cable-modem des show controllers cable-modem filters show controllers cable-modem lookup-table show controllers cable-modem phy show controllers cable-modem tuner Cisco IOS Release 12.0(3)T...

  • Page 45: Syntax Description

    To display the contents of the registers used in the downstream physical hardware of the Cisco uBR904 cable modem, use the show controllers cable-modem phy command in privileged EXEC mode. show controllers cable-modem phy {receive | transmit}...
  • Page 46 01 00 06 01 22 07 02 01 52 08 01 00 09 01 30 0A Related Commands show controllers cable-modem show controllers cable-modem bpkm show controllers cable-modem des show controllers cable-modem filters show controllers cable-modem lookup-table show controllers cable-modem mac show controllers cable-modem tuner Cisco IOS Release 12.0(3)T...
  • Page 47 To display the settings for the upstream and downstream tuners used by a Cisco uBR904 cable modem, use the show controllers cable-modem tuner command in privileged EXEC mode. show controllers cable-modem tuner Syntax Description There are no key words or arguments for this command.
  • Page 48 Command Reference Related Commands show controllers cable-modem show controllers cable-modem bpkm show controllers cable-modem des show controllers cable-modem filters show controllers cable-modem lookup-table show controllers cable-modem mac show controllers cable-modem phy Cisco IOS Release 12.0(3)T...

  • Page 49: Debug Commands

    The following new debug commands are available to troubleshoot a cable modem: • debug cable-modem • debug cable-modem bpkm • debug cable-modem bridge • debug cable-modem error • debug cable-modem interrupts • debug cable-modem mac • debug cable-modem map Troubleshooting Tips for the Cisco uBR904 Cable Modem 49...
  • Page 50 Debugs baseline privacy packets. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Examples Figure 3 shows the required keywords within the debug cable-modem bpkm command. You must choose one. Figure 3...
  • Page 51 Related Commands debug cable-modem bridge debug cable-modem error debug cable-modem interrupts debug cable-modem mac debug cable-modem map Troubleshooting Tips for the Cisco uBR904 Cable Modem 51...
  • Page 52 Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. When the interface is down, all bridge table entries learned on the Ethernet interface are set to discard because traffic is not bridged until the cable interface has completed initialization. After the interface (the line protocol) is completely up, bridge table entries learned on the Ethernet interface program the cable’s MAC data filters.
  • Page 53 Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. This command displays detailed output about the sanity checking of received frame formats, the acquisition of downstream QAM/FEC lock, the receipt or non-receipt of SYNC messages from the CMTS, reception errors, and bandwidth request failures.
  • Page 54 This command has no keywords or arguments. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Examples Figure 7 shows sample debug output for cable modem interrupts. Figure 7 Sample Debug Cable-Modem Interrupts Output...
  • Page 55 Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Of all the available debug cable modem commands, the most useful is debug cable-modem mac log. Mac log messages are written to a circular log file even when debugging is not turned on. These messages include timestamps, events, and information pertinent to these events.
  • Page 56 528428.726 CMAC_LOG_RNG_REQ_TRANSMITTED 528428.728 CMAC_LOG_RNG_RSP_MSG_RCVD 528438.796 CMAC_LOG_RNG_REQ_TRANSMITTED 528438.798 CMAC_LOG_RNG_RSP_MSG_RCVD 528444.102 CMAC_LOG_WATCHDOG_TIMER 528444.492 CMAC_LOG_LINK_DOWN 528444.494 CMAC_LOG_RESET_FROM_DRIVER 528444.494 CMAC_LOG_STATE_CHANGE wait_for_link_up_state 528444.494 CMAC_LOG_DRIVER_INIT_IDB_SHUTDOWN 0x08098D02 528444.494 CMAC_LOG_LINK_DOWN 528474.494 CMAC_LOG_WATCHDOG_TIMER 528504.494 CMAC_LOG_WATCHDOG_TIMER 528534.494 CMAC_LOG_WATCHDOG_TIMER 0 events dropped due to lack of a chunk Cisco IOS Release 12.0(3)T...
  • Page 57 7 01:44:06: MAC MANAGEMENT MESSAGE HEADER *Mar 7 01:44:06: - 01E0.2F00.0001 *Mar 7 01:44:06: - 00E0.1EA5.BB60 *Mar 7 01:44:06: msg LEN - C1 *Mar 7 01:44:06: DSAP *Mar 7 01:44:06: SSAP Troubleshooting Tips for the Cisco uBR904 Cable Modem 57...
  • Page 58 - 0x0152 *Mar 7 01:44:06: Maximum Burst Size *Mar 7 01:44:06: Guard Time Size *Mar 7 01:44:06: Last Codeword Length - 1 == FIXED *Mar 7 01:44:06: Scrambler on/off - 1 == ON *Mar 7 01:44:06: Cisco IOS Release 12.0(3)T...
  • Page 59 - 0x29 *Mar 7 01:44:20: MAC MANAGEMENT MESSAGE HEADER *Mar 7 01:44:20: - 00F0.1EB2.BB61 Related Commands debug cable-modem bpkm debug cable-modem bridge debug cable-modem error debug cable-modem interrupts debug cable-modem map Troubleshooting Tips for the Cisco uBR904 Cable Modem 59...
  • Page 60 This command has no keywords or arguments. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Examples Figure 11 shows display output for the debug cable map Privileged EXEC command. Figure 11 Sample Debug Cable-Modem Map Output...

  • Page 61: What To Do Next

    For more troubleshooting tips, see the chapter “Troubleshooting the Installation” in the Cisco Cable Modem Installation and Configuration Guide. For an explanation of error messages displayed by the uBR904, see Cisco Cable CPE Error Messages, viewable online at www.cisco.com/univercd/cc/td/doc/product/cable/cab_modm/ubcmerrs.pdf .
  • Page 62 What to do Next Cisco IOS Release 12.0(3)T...

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