The Impairment column in Alarm Central on the SC-QAM and OFDM/A tabs shows reasons why a modem might be unable to use a configured upstream or downstream channel.
Possible reasons include:
SC-QAM
- none
- No impairment exists.
- other(1)
- Any state not described by one of the values below.
- aborted(2)
- The CMTS sent a ranging abort.
- retriesExceeded(3)
- The cable modem ranging retry limit has been exceeded.
- continue(5)
- The CMTS has sent a ranging continue in the ranging response.
- timeoutT4(6)
- The T4 timer expired on the cable modem.
NOTE: Downstream channels show other(1) when MER=0 or SNR=0. Otherwise, downstream channel value is none(0).
OFDM/A
- none
- No impairment exists.
- secondaryChanMddTimeout(1)
- A CM-STATUS event type 1 has been received, indicating a secondary channel MAC domain descriptor (MDD) timeout.
- lostFecLock(2)
- The cable modem reports that the forward error correction (FEC) lock has been lost for one or more downstream channels that were previously available.
- iuc13CwErrors(3)
- Codeword errors are over limit on IUC 13 of an OFDMA channel; the criteria for this decision are vendor-specific.
- qamFecLockFailure(100)
- The cable modem reports a quadrature amplitude modulation (QAM)/FEC lock failure on a downstream channel.
- plcFecLockFailure(130)
- The cable modem reports that the physical link channel (PLC) FEC lock has been lost on an OFDM channel.
- ncpFecLockFailure(150)
- The cable modem reports that the next codeword pointer (NCP) FEC data lock has been lost on an OFDM channel.
- prof0FecLockFailure(170)
- The cable modem reports that the lowest available profile (prof0) FEC lock has been lost. The lowest available profile should be usable by any modem.
- unknownMdDsSgId(200)
- The cable modem reports a bad downstream service group ID, or the CMTS is unable to determine the DS-SG-ID for the modem.
- iuc13ProfileFailure(230)
- The cable modem reports a profile failure for IUC 13 on an OFDMA channel.
- usFecFailure(250)
- The cable modem reports FEC failures for an upstream SC-QAM channel.
- unknownMdUsSgId(300)
- The cable modem reports a bad upstream service group ID, or the CMTS is unable to determine the US-SG-ID for the modem.
- badRcs(400)
- Bad Receive Channel Set. The cable modem reports it is unable to tune to and receive a downstream channel assigned in the Receive Channel Configuration. This may indicate an undiagnosed connectivity problem or a cable modem receiver problem.
- badTcs(500)
- Bad Transmit Channel Set. The cable modem reports it is unable to successfully range on one or more upstream channels assigned in the Transmit Channel Configuration. This reason may indicate an undiagnosed connectivity problem in the cable network whereby the true connectivity does not match the provisioned connectivity. It may also indicate one or more corrupted upstream channels. This reason may also indicate that the supervision for one or more upstream channels cannot be found within the Receive Channel Set.
- t4Timeout(600)
- The cable modem reports a timeout event occurred for DOCSIS timer T4.
- t3Timeout(700)
- The cable modem reports consecutive timeouts of timer T3 (ranging response timer) exceeded the maximum.
- usStationMaintFailure(900)
- The cable modem is experiencing periodic ranging failure.