DOCSIS 3.0 Downstream SC-QAM Codeword Error Rate¶

Computes per-channel codeword error statistics for DOCSIS 3.0 downstream SC-QAM channels: uncorrectables, normalized error rates, and codeword throughput over a configurable sampling interval.

Endpoint¶

POST /docs/if30/ds/scqam/chan/codewordErrorRate

Request¶

Use the SNMP-only format described in Common → Request.
TFTP parameters are not required for this measurement.

Additional request fields¶

JSON path	Type	Default	Description
`capture_parameters.sample_time_elapsed`	number	`5`	Sampling interval in seconds used to compute per-second statistics.

Example¶

{
  "cable_modem": {
    "mac_address": "aa:bb:cc:dd:ee:ff",
    "ip_address": "192.168.0.100",
    "snmp": {
      "snmpV2C": { "community": "private" }
    }
  },
  "capture_parameters": {
    "sample_time_elapsed": 5
  }
}

Response¶

This endpoint returns the standard envelope described in Common → Response (mac_address, status, message, data).

The data field is an array of per-channel codeword error summaries for each detected downstream SC-QAM channel.

Abbreviated example¶

{
  "mac_address": "aa:bb:cc:dd:ee:ff",
  "status": 0,
  "message": "Successfully retrieved codeword error rate",
  "data": [
    {
      "index": 52,
      "channel_id": 32,
      "codeword_totals": {
        "total_codewords": 1290014,
        "total_errors": 0,
        "time_elapsed": 5,
        "error_rate": 0,
        "codewords_per_second": 258002.8,
        "errors_per_second": 0
      }
    },
    {
      "index": 53,
      "channel_id": 31,
      "codeword_totals": {
        "total_codewords": 1290014,
        "total_errors": 0,
        "time_elapsed": 5,
        "error_rate": 0,
        "codewords_per_second": 258002.8,
        "errors_per_second": 0
      }
    },
    { "...": "other channels elided" }
  ]
}

Channel fields¶

Field	Type	Description
`index`	int	SNMP table index (OID instance) for this channel row in the CM codeword table.
`channel_id`	int	DOCSIS downstream SC-QAM logical channel ID.

Codeword total fields¶

Field	Type	Description
`total_codewords`	int	Total codewords counted over the sampling interval.
`total_errors`	int	Uncorrectable codeword errors over the sampling interval.
`time_elapsed`	number	Sampling interval used (seconds).
`error_rate`	number	Fraction of uncorrectables (`total_errors/total_codewords`).
`codewords_per_second`	number	Normalized codewords per second (s⁻¹).
`errors_per_second`	number	Normalized errors per second (s⁻¹).

Rates use SI unit s⁻¹; multiply error_rate by 100 to get a percentage.

Notes¶

Ensure SNMP counters are 64-bit to avoid overflow on high-traffic channels.
sample_time_elapsed defaults to 5 seconds if omitted; align it with your polling cadence.
The modem is automatically scanned for all downstream SC-QAM channels—no manual channel list is required.