Troubleshooting guide
7-10
Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 7 Troubleshooting the CMTS
Troubleshooting the Cisco uBR7246VXR
4d00h: 345781.280 CMAC_LOG_RNG_RSP_MSG_RCVD
4d00h: 345781.282 CMAC_LOG_RNG_RSP_SID_ASSIGNED 3
4d00h: 345781.284 CMAC_LOG_ADJUST_RANGING_OFFSET 2288
4d00h: 345781.288 CMAC_LOG_RANGING_OFFSET_SET_TO 11898
4d00h: 345781.292 CMAC_LOG_ADJUST_TX_POWER 7
4d00h: 345781.294 CMAC_LOG_POWER_LEVEL_IS 24.0 dBmV (comma)
4d00h: 345781.298 CMAC_LOG_STATE_CHANGE ranging_2_state
4d00h: 345781.302 CMAC_LOG_RNG_REQ_QUEUED 3
4d00h: 345782.298 CMAC_LOG_RNG_REQ_TRANSMITTED
4d00h: 345782.300 CMAC_LOG_RNG_RSP_MSG_RCVD
4d00h: 345782.304 CMAC_LOG_RANGING_SUCCESS
4d00h: 345782.316 CMAC_LOG_STATE_CHANGE dhcp_state
4d00h: 345782.450 CMAC_LOG_DHCP_ASSIGNED_IP_ADDRESS 10.1.1.25
4d00h: 345782.452 CMAC_LOG_DHCP_TFTP_SERVER_ADDRESS 172.17.110.136
4d00h: 345782.456 CMAC_LOG_DHCP_TOD_SERVER_ADDRESS 172.17.110.136
4d00h: 345782.460 CMAC_LOG_DHCP_SET_GATEWAY_ADDRESS
4d00h: 345782.464 CMAC_LOG_DHCP_TZ_OFFSET 0
4d00h: 345782.466 CMAC_LOG_DHCP_CONFIG_FILE_NAME frequency.cm
4d00h: 345782.470 CMAC_LOG_DHCP_ERROR_ACQUIRING_SEC_SVR_ADDR
4d00h: 345782.474 CMAC_LOG_DHCP_COMPLETE
4d00h: 345782.598 CMAC_LOG_STATE_CHANGE establish_tod_state
4d00h: 345782.606 CMAC_LOG_TOD_REQUEST_SENT
4d00h: 345782.620 CMAC_LOG_TOD_REPLY_RECEIVED 3178880491
4d00h: 345782.628 CMAC_LOG_TOD_COMPLETE
4d00h: 345782.630 CMAC_LOG_STATE_CHANGE security_associate_state
4d00h: 345782.634 CMAC_LOG_SECURITY_BYPASSED
4d00h: 345782.636 CMAC_LOG_STATE_CHANGE configuration_file
4d00h: 345782.640 CMAC_LOG_LOADING_CONFIG_FILE frequency.cm
4d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface cable-modem0, changed state to up
4d00h: 345783.678 CMAC_LOG_CONFIG_FILE_PROCESS_COMPLETE
NOTE—frequency override:
4d00h: 345783.682 CMAC_LOG_DS_FREQ_OVERRIDE 535250000
4d00h: 345783.686 CMAC_LOG_STATE_CHANGE reset_hardware_state
4d00h: 345784.048 CMAC_LOG_STATE_CHANGE wait_for_link_up_state
4d00h: 345784.052 CMAC_LOG_DRIVER_INIT_IDB_RESET 0x082A5226
4d00h: 345784.054 CMAC_LOG_LINK_DOWN
4d00h: 345784.056 CMAC_LOG_LINK_UP
4d00h: 345784.062 CMAC_LOG_STATE_CHANGE ds_channel_scanning_state
4d00h: 345785.198 CMAC_LOG_DS_NO_QAM_FEC_LOCK 535250000
4d00h: 345785.212 CMAC_LOG_DS_TUNER_KEEPALIVE
4d00h: 345787.018 CMAC_LOG_UCD_MSG_RCVD 1
4d00h: 345787.022 CMAC_LOG_DS_64QAM_LOCK_ACQUIRED 453000000
Incorrect frequency specified in cable modem change-frequency on the Cisco uBR7246VXR can also
cause the MTA to switch frequencies, and if the frequency configured on the router is not chosen
carefully, then you will see results similar to that above. The cable modem change-frequency command
on the Cisco uBR7246VXR is optional and is typically left out by default.
After a downstream channel has been acquired and latency has been calculated, the next task is to locate
a suitable upstream channel. the cable modem listens for an upstream channel descriptor (UCD) which
contains the physical properties of the upstream channel, such as frequency, modulation, channel width,
and other parameters defined in the burst descriptors.
A cable modem that cannot find a usable upstream channel descriptor may be on a downstream channel
for which no upstream service is provided. This is likely to be a faulty configuration of the router. The
show controller cable x command is a good place to start. Another possible reason a cable modem may
not find a usable UCD is that its hardware or MAC may not support the parameters in the burst
descriptors. This is likely to be either a faulty configuration of the Cisco uBR7246VXR or an MTA that
is not DOCSIS-compliant.