Cisco UBR924 - uBR 924 Router Troubleshooting Tips page 15

The search table is arranged so that the first frequencies tried are above 450 MHz. Because many
CATV systems have been upgraded from 450 MHz to 750 MHz coaxial cable, digital channels have
a high chance of being assigned in the new spectrum. The search table omits channels below 90 MHz
and above 860 MHz since the DOCSIS specification does not mandate their coverage.
Some CATV systems use alternative frequency plans such as the IRC (Incrementally Related
Carrier) plan and HRC (Harmonically Related Carrier) plan. Cisco cable access routers support both
of these plans. Most of the IRC channel slots overlap the EIA plan.
Event 3—Obtain Upstream Parameters
The Cisco uBR924 waits for an upstream channel descriptor (UCD) message from the headend
CMTS. The UCD provides transmission parameters for the upstream channel.
508146.124 CMAC_LOG_STATE_CHANGE
508147.554 CMAC_LOG_UCD_MSG_RCVD
508147.558 CMAC_LOG_UCD_NEW_US_FREQUENCY
508147.558 CMAC_LOG_SLOT_SIZE_CHANGED
508147.622 CMAC_LOG_FOUND_US_CHANNEL
508147.624 CMAC_LOG_STATE_CHANGE
508148.058 CMAC_LOG_MAP_MSG_RCVD
508148.060 CMAC_LOG_INITIAL_RANGING_MINISLOTS
Event 4—Start Ranging for Power Adjustments
The ranging process adjusts the transmit power of the cable access router. The Cisco uBR924
performs ranging in two stages: ranging state 1 and ranging state 2.
The
CMAC_LOG_POWER_LEVEL_IS
adjust to. The
CMAC_LOG_RANGING_SUCCESS
successful.
508148.062 CMAC_LOG_STATE_CHANGE
508148.064 CMAC_LOG_RANGING_OFFSET_SET_TO
508148.066 CMAC_LOG_POWER_LEVEL_IS
508148.068 CMAC_LOG_STARTING_RANGING
508148.070 CMAC_LOG_RANGING_BACKOFF_SET
508148.072 CMAC_LOG_RNG_REQ_QUEUED
508148.562 CMAC_LOG_RNG_REQ_TRANSMITTED
508148.566 CMAC_LOG_RNG_RSP_MSG_RCVD
508148.568 CMAC_LOG_RNG_RSP_SID_ASSIGNED
508148.570 CMAC_LOG_ADJUST_RANGING_OFFSET
508148.572 CMAC_LOG_RANGING_OFFSET_SET_TO
508148.574 CMAC_LOG_ADJUST_TX_POWER
508148.576 CMAC_LOG_POWER_LEVEL_IS
508148.578 CMAC_LOG_STATE_CHANGE
508148.580 CMAC_LOG_RNG_REQ_QUEUED
508155.820 CMAC_LOG_RNG_REQ_TRANSMITTED
508155.824 CMAC_LOG_RNG_RSP_MSG_RCVD
508155.826 CMAC_LOG_ADJUST_RANGING_OFFSET
508155.826 CMAC_LOG_RANGING_OFFSET_SET_TO
508155.828 CMAC_LOG_RANGING_CONTINUE
508165.892 CMAC_LOG_RNG_REQ_TRANSMITTED
508165.894 CMAC_LOG_RNG_RSP_MSG_RCVD
508165.896 CMAC_LOG_ADJUST_TX_POWER
508165.898 CMAC_LOG_POWER_LEVEL_IS
508165.900 CMAC_LOG_RANGING_CONTINUE
508175.962 CMAC_LOG_RNG_REQ_TRANSMITTED
508175.964 CMAC_LOG_RNG_RSP_MSG_RCVD
508175.966 CMAC_LOG_RANGING_SUCCESS
Step 4—Interpret the MAC Log File and Take Action
field is the power level that the CMTS told the Cisco uBR924 to
field indicates that the ranging adjustment was
Troubleshooting Tips for the Cisco uBR924 Cable Access Router 15
wait_ucd_state
3
20000000
8
1
wait_map_state
40
ranging_1_state
9610
28.0 dBmV (commanded)
0
0
2
2408
12018
20
33.0 dBmV (commanded)
ranging_2_state
2
-64
11954
-9
31.0 dBmV (commanded)