Troubleshooting Tips for the Cisco uBR904 Cable Modem The following sections are provided: • • • • • • • • Feature Summary on page 1 Prerequisites on page 3 Supported MIBs and RFCs on page 3 CMTS to Cable Modem Network Topology on page 4 Troubleshooting Tips on page 5 Command Reference on page 16 Debug Commands on page 42 What to do Next on page 54 Feature Summary This document provides MSOs (multiple service operators) with a set of software tools for troubleshooting a cable modem for data-over-cable co
Feature Summary List of Terms CATV—Originally stood for Community Antenna Television. CATV now refers to any cable (coaxial/fiber) based system that provides television services. Cable modem—Any device that modulates and demodulates digital data onto a CATV plant. Cable router—A modular chassis-based router optimized for the data over CATV HFC applications. Channel—A specific frequency allocation and bandwidth. Downstream channels used for television in the U. S. are 6 MHz wide. CM—Cable modem.
List of Terms Prerequisites Cisco IOS Release 11.3(4)NA or later must be running inside the cable modem. Enter the show version EXEC command to display the software version level. Supported MIBs and RFCs The Cisco uBR904 cable modem supports the following: • Radio Frequency Interface Specification—This specification is developed by the Multimedia Cable Network System (MCNS) corsortium. It defines the radio-frequency interface specification for high-speed data-over-cable systems.
CMTS to Cable Modem Network Topology CMTS to Cable Modem Network Topology Figure 1 shows the physical relationship between the devices in the HFC network and the cable modem. Figure 1 Sample Topology ISP WAN IP-related ATM, FDDI, 100BT... 100BT 100BT Proxy server Cisco uBR7246 CMTS Analog TV 100BT ISP @ home...
Understand How Basic Initialization Works Troubleshooting Tips Perform the following steps to troubleshoot a cable modem: • • • • • Step 1—Understand How Basic Initialization Works Step 2—Connect to the Cable Modem Step 3—Display the Cable Modem’s MAC Log File Step 4—Interpret the MAC Log File and Take Action Step 5—(Optional) Use Additional Troubleshooting Commands Understand How Basic Initialization Works Before you troubleshoot a cable modem, you should be familiar with the cable modem initialization
Troubleshooting Tips Figure 2 Cable Modem Initialization Flowchart Power on 1 2 3 4 5 Scan for downstream channel Establish security Downstream sync established Security established Obtain upstream parameters Transfer operational parameters Upstream parameter acquired Transfer complete Start Ranging Register with the Cisco uBR7246 Ranging and auto adjust completed Registration complete Establish IP connectivety Baseline privacy initialization IP complete Baseline privacy initialized
Connect to the Cable Modem . Table 1 Cable Modem Initialization Sequences and Events Sequence Event Description 1 Scan for a downstream channel and establish synchronization with the headend Cisco uBR7246. The cable modem acquires a downstream channel from the headend, saves the last operational frequency in non-volatile memory, and tries to reacquire the saved downstream channel the next time a request is made.
Troubleshooting Tips Display the Cable Modem’s MAC Log File A MAC layer circular log file is inside the cable modem. This file contains a history of log messages, such as state event activities and timestamps, which are used for troubleshooting purposes. This log file contains the most valuable information for a cable technician or engineer to debug the cable interface. The MAC log file is displayed by entering the show controller cable-modem 0 mac log EXEC command.
Display the Cable Modem’s MAC Log File 508146.122 508146.124 508147.554 508147.558 508147.558 508147.622 508147.624 508148.058 508148.060 508148.062 508148.064 508148.066 508148.068 508148.070 508148.072 508148.562 508148.566 508148.568 508148.570 508148.572 508148.574 508148.576 508148.578 508148.580 508155.820 508155.824 508155.826 508155.826 508155.828 508165.892 508165.894 508165.896 508165.898 508165.900 508175.962 508175.964 508175.966 508175.968 508176.982 508176.984 508176.986 508176.988 508176.
Troubleshooting Tips You can display other aspects of the MAC layer by using variations of the show controller cable-modem 0 mac command: uBR904# show controller cable-modem 0 mac ? errors Mac Error Log data hardware All CM Mac Hardware registers log Mac log data resets Resets of the MAC state Current MAC state For examples and descriptions on how to use these keywords, see the show controller cable-modem mac command reference page.
Interpret the MAC Log File and Take Action Event 2—Scan for a Downstream Channel then Synchronize Different geographical regions and different cable plants use different frequency bands. The Cisco uBR904 cable modem uses a built-in default frequency scanning feature to address this issue. After the cable modem finds a successful downstream frequency channel, it saves the channel to NVRAM. The cable modem recalls this value the next time it needs to synchronize its frequency.
Troubleshooting Tips Event 3—Obtain Upstream Parameters The cable modem waits for an upstream channel descriptor messages (UCD) from the headend Cisco uBR7246. This is done to retrieve transmission parameters for the upstream channel. 508146.124 508147.554 508147.558 508147.558 508147.622 508147.624 508148.058 508148.
Interpret the MAC Log File and Take Action Event 5—Establish IP Connectivity After ranging is complete, the cable interface on the cable modem is up. Now the cable modem accesses a remote DHCP server to get an IP address. The DHCP request also includes the name of a file that contains additional configuration parameters, the TFTP server’s address, and the Time of Day (TOD) server’s address.
Troubleshooting Tips Event 8—Transfer Operational Parameters After the DHCP and security operations are successful, the cable modem downloads operational parameters from a cable company’s TFTP server. These parameters are transferred via a configuration file. The field CMAC_LOG_DHCP_CONFIG_FILE_NAME shows the filename containing the transmission parameters. 508177.164 CMAC_LOG_STATE_CHANGE 508177.166 CMAC_LOG_LOADING_CONFIG_FILE 508178.
Use Additional Troubleshooting Commands Event 11—Enter the Maintenance State As soon as the cable modem is completely up and running, it enters the operational maintenance state. 508178.322 CMAC_LOG_STATE_CHANGE maintenance_state Use Additional Troubleshooting Commands You can use other show controller and debug cable modem commands to troubleshoot different aspects of a cable modem. However, the most useful command is the show controller cable-modem 0 mac command.
Command Reference Command Reference This section provides new commands for troubleshooting the Cisco uBR904 cable modem. All other commands used with this feature are documented in the Cisco IOS Release 11.3 command references. • • • • • • • • • 16 Release 11.
show controller cable-modem show controller cable-modem To display high-level controller information about a cable modem, use the show controller cable-modem Privileged EXEC command. Syntax Description number Controller number inside the cable modem. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA.
Command Reference Global control and status: global_ctrl_status=0x00 interrupts: irq_pend=0x0008, irq_mask=0x00F7 Related Commands show controller cable-modem bpkm show controller cable-modem des show controller cable-modem filters show controller cable-modem lookup-table show controller cable-modem mac show controller cable-modem phy show controller cable-modem tuner show interface cable-modem 18 Release 11.
show controller cable-modem bpkm show controller cable-modem bpkm To display information about the baseline privacy key management exchange between the cable modem and the headend CMTS, use the show controller cable-modem bpkm Privileged EXEC command. show controller cable-modem number bpkm Syntax Description number Controller number inside the cable modem. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA.
Command Reference show controller cable-modem des To display information about the Data Encryption Standard (DES) engine registers, use the show controller cable-modem des Privileged EXEC command. show controller cable-modem des Syntax Description This command has no key words or arguments. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA.
show controller cable-modem des Related Commands show controller cable-modem show controller cable-modem bpkm show controller cable-modem filters show controller cable-modem lookup-table show controller cable-modem mac show controller cable-modem phy show controller cable-modem tuner show interface cable-modem Troubleshooting Tips for the Cisco uBR904 Cable Modem 21
Command Reference show controller cable-modem filters To display the registers in the MAC hardware that are used for filtering received frames, use the show controller cable-modem filters Privileged EXEC command. show controller cable-modem filters Syntax Description There are no key words or arguments for this command. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA.
show controller cable-modem filters Related Commands show controller cable-modem show controller cable-modem bpkm show controller cable-modem des show controller cable-modem lookup-table show controller cable-modem mac show controller cable-modem phy show controller cable-modem tuner show interface cable-modem Troubleshooting Tips for the Cisco uBR904 Cable Modem 23
Command Reference show controller cable-modem lookup-table To display the mini-slot lookup table inside a cable modem, use the show controller cable-modem lookup-table Privileged EXEC command. show controller cable-modem lookup-table Syntax Description This command has no keywords or arguments. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. This command shows the details of the lookup table.
show controller cable-modem lookup-table 1C 1D 1E 1F 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F 30 31 32 33 34 35 36 37 38 . . .
Command Reference show controller cable-modem mac To show detailed MAC layer information for a cable modem, enter the show cable controller cable-modem number mac Privileged EXEC command. show controller cable-modem number mac [errors | hardware | log | resets | state] Syntax Description number The controller number inside the cable modem. errors (Optional) Displays a log of the error events that are reported to SNMP. This keyword gives you a way of looking at the error events without using a MIB.
show controller cable-modem mac Sample Display 1 The following sample display shows the MAC log file for a cable-modem interface that has successfully come up: uBR904# *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7 *Mar 7
Command Reference *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 01:43:15: 01:43:15: 01:43:15: 01:43:15: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 01:43:16: 528317.958 528317.960 528317.962 528317.964 528318.968 528318.970 528318.
show controller cable-modem mac Sample Displays 3 The show controller cable-modem 0 mac resets command shows only the entries in the cable MAC log that begin with the field CMAC_LOG_RESET. Collectively presenting these fields provides you with a summary of the most recent reasons why the cable interface was reset. Reset messages and brief explainations are included in the following examples and in Table 1. However, the reset messages in Table 2 do not commonly occur.
Command Reference Table 2 Possible but Uncommon Cable Interface Reset Causes (Continued) Message Description CMAC_LOG_RESET_PRIVACY_WATCHDOG_EXPIRED The baseline privacy exchange with the CMTS took too long. CMAC_LOG_RESET_CHANGE_US_WATCHDOG_EXPIRED The cable modem was unable to transmit a response to a UCC-REQ message. CMAC_LOG_RESET_SECURITY_WATCHDOG_EXPIRED The “full security” exchange with the CMTS took too long.
show controller cable-modem mac Table 2 Possible but Uncommon Cable Interface Reset Causes (Continued) Message Description CMAC_LOG_RESET_NO_SEND_TO_DS_TUNER_PROCESS The modem MAC layer process was unable to communicate with the downstream tuner management process. CMAC_LOG_RESET_DS_TUNER_WATCHDOG The downstream tuner process failed to report it's continuing operation for a long period of time.
Command Reference 27 pak=0x82DC904 buf=0x21D65A status=0x80 pak_size=0 28 pak=0x82DC70C buf=0x21CF52 status=0x80 pak_size=0 29 pak=0x82DC514 buf=0x21C84A status=0x80 pak_size=0 30 pak=0x82DC31C buf=0x21C142 status=0x80 pak_size=0 31 pak=0x82DC124 buf=0x21BA3A status=0xA0 pak_size=0 RX MAC message ring with 8 entries at 0x201E80 rx_head_mac = 0x201EB0 (6), rx_p_mac = 0x82D480C (6) 00 pak=0x82E0DEC buf=0x22CC72 status=0x80 pak_size=0 01 pak=0x82E021C buf=0x22A242 status=0x80 pak_size=0 02 pak=0x82E060C buf=0
show controller cable-modem mac timing recovery circuit: loop_enable=0x00, minislot_divisor=0x00 K0_ctrl=0x06, K1_ctrl=0x07, acq_threshhold=0x01 err_threshhold=0x04, timeout_threshold=0xFF nco_bias=0x4F7004F7, ranging_offset=0x00000000 ts_err=0x00, sync_valid=0x00, delta_F=0x00 timeout_err=0x00 spi: dynamic_ctrl=0x09, static_ctr=0x9F, autonomous=0x01 irq_ack=0x00, spi_cmd=0x51, spi_addr=0x11 spi_data= FF/00/00/00/00/00/00 burst profiles: profile 0: 01 19 1D 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0
Command Reference 98 219000000 225000000 6000000 99 177000000 213000000 6000000 US ID: 1 US Frequency: 20000000 US Power Level: 34.
show controller cable-modem mac Baseline Privacy: Auth. Wait Timeout: Reauth. Wait Timeout: Auth. Grace Time: Op. Wait Timeout: Retry Wait Timeout: TEK Grace Time: Auth.
Command Reference show controller cable-modem phy To display detailed contents about the registers used in the downstream physical hardware used by a cable modem, use the show controller cable-modem phy Privileged EXEC command. show controller cable-modem phy {receive | transmit} Syntax Description receive Displays all receive registers in the downstream physical hardware. transmit Displays all transmit registers in the upstream physical hardware.
show controller cable-modem phy Physical transmit registers are displayed in the following example: uBR904# show controller cable-modem 0 phy transmit BCM3037 Transmitter Registers: part_id = 3037 rev_id = 01 test_mode = 00 test_input = 00 test_misc = 2009 rst = 00 power = 0000 power_2 = 00 port = 6F pll = F7 map = 66 mod = 28 tx_oen_bdly = 14 tx_oen_edly = C8 prbs_cfg = 00C000 baud = 1A36E3 burst = 0000 if_freq = 200000 dac = 37 tx_config = 00 burst config 0 : prbs_init fec pream_len burst config 1 : prbs
Command Reference show controller cable-modem tuner To display the settings for the upstream and downstream tuners used by a cable modem, use the show controller cable-modem tuner Privileged EXEC command. show controller cable-modem tuner Syntax Description There are no key words or arguments for this command. Command Mode Privileged EXEC Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Sample Display The cable modem’s tuner settings are displayed in the following example.
show controller cable-modem tuner show controller cable-modem mac show controller cable-modem phy show interface cable-modem Troubleshooting Tips for the Cisco uBR904 Cable Modem 39
Command Reference show interface cable-modem To display information about the cable modem interface on a cable modem, use the show interface cable-modem EXEC command. show interface cable-modem number [accounting | counters | crb | irb | type] Syntax Description number Cable modem interface number. accounting (Optional) Displays the number of packets of each protocol type that has been sent through the cable modem interface. counters (Optional) Shows MIB counters on the cable interface.
show interface cable-modem The following example displays the number of packets and each protocol type passing through the cable modem interface: uBR904# show int cable-modem 0 accounting cable-modem0 Protocol Pkts In Chars In IP 545 185502 Trans.
Debug Commands Debug Commands The following new debug commands are available to troubleshoot a cable modem: • • • • • • 42 Release 11.
debug cable-modem bpkm debug cable-modem bpkm To debug baseline privacy information on a cable modem, use the debug cable-modem mac Privileged EXEC command. The no form of this command turns debugging messages off. [no] debug cable-modem bpkm {errors | events | packets} Syntax Description errors Debugs cable modem privacy errors. events Debugs events related to cable baseline privacy. packets Debugs baseline privacy packets.
Debug Commands Related Commands debug cable-modem bridge debug cable-modem error debug cable-modem interrupts debug cable-modem mac debug cable-modem map 44 Release 11.
debug cable-modem bridge debug cable-modem bridge Use the debug cable-modem bridge Privileged EXEC command to debug bridge filter processing information on a cable modem. The no form of this command turns debugging messages off. [no] debug cable-modem bridge Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA.
Debug Commands debug cable-modem error Use the the debug cable-modem error Privileged EXEC command to enable debugging messages for the cable interface driver. The no form of this command turns debugging messages off. [no] debug cable-modem error Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA.
debug cable-modem interrupts debug cable-modem interrupts Use the debug cable-modem interrupts command to debug cable modem interrupts. The no form of this command turns debugging messages off. [no] debug cable-modem interrupts Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Sample Display Figure 7 shows sample debug output for cable modem interrupts.
Debug Commands debug cable-modem mac Use the debug cable-modem mac Privileged EXEC command to troubleshoot the cable modem MAC layer. The no form of this command turns debugging messages off. [no] debug cable-modem mac {log [verbose] | messages} Syntax Description log Realtime MAC log display. verbose (Optional) Displays periodic MAC layer events, such as ranging. messages MAC layer management messages. Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA.
debug cable-modem mac Figure 8 Sample Debug Cable-Modem Mac Log Output uBR904# debug cable-modem mac log *Mar 7 01:42:59: 528302.040 CMAC_LOG_LINK_DOWN *Mar 7 01:42:59: 528302.042 CMAC_LOG_RESET_FROM_DRIVER *Mar 7 01:42:59: 528302.044 CMAC_LOG_STATE_CHANGE wait_for_link_up_state *Mar 7 01:42:59: 528302.046 CMAC_LOG_DRIVER_INIT_IDB_SHUTDOWN 0x08098D02 *Mar 7 01:42:59: 528302.048 CMAC_LOG_LINK_DOWN *Mar 7 01:43:05: 528308.428 CMAC_LOG_DRIVER_INIT_IDB_RESET 0x08098E5E *Mar 7 01:43:05: 528308.
Debug Commands Figure 9 compares the output of the debug cable-modem mac log command with the debug cable-modem mac log verbose command. The keyword verbose displays periodic events such as ranging. Figure 9 Sample Debug Cable-Modem Mac Log and Verbose Output uBR904# debug cable mac log Cable Modem mac log debugging is on uBR904# uBR904# uBR904# debug cable mac log verbose Cable Modem mac log debugging is on (verbose) uBR904# 574623.810 CMAC_LOG_RNG_REQ_TRANSMITTED 574623.
debug cable-modem mac *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar CC 0D *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 7 01:44:06: 0D 7 01:44:06: 7 01:44:06: 7 0
Debug Commands *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar . . . *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar . . . *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar *Mar . . .
debug cable-modem map debug cable-modem map Use the debug cable-modem map Privileged EXEC command to display the timing from MAP messages to sync messages and the timing between MAP messages. The no form of this command disables debugging output. [no] debug cable-modem map Usage Guidelines This command first appeared in Cisco IOS Release 11.3 NA. Sample Display Figure 11 shows display output for the debug cable map Privileged EXEC command.
What to do Next What to do Next For more troubleshooting tips, see the chapter “Troubleshooting the Installation” in the Cisco Cable Modem Installation and Configuration Guide. 54 Release 11.
