DOCSIS 3.1 Downstream OFDM Channel Statistics¶

Fetches Downstream OFDM Channel Configuration And Performance Data From A DOCSIS 3.1 Cable Modem Using SNMP.

Endpoint¶

POST /docs/if31/ds/ofdm/channel/stats

Request¶

Use the SNMP-only format: Common → Request TFTP parameters are not required.

Response¶

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

device is the top-level device identity block and contains device.mac_address and device.system_description (empty model when unavailable).

data is an array of downstream OFDM channels. Each item contains the SNMP table index, the channel_id, and an entry with DS-OFDM configuration and statistics.

Abbreviated Example¶

{
  "mac_address": "aa:bb:cc:dd:ee:ff",
  "status": 0,
  "message": null,
  "data": [
    {
      "index": 48,
      "channel_id": 34,
      "entry": {
        "docsIf31CmDsOfdmChanChanIndicator": "nonPrimary",
        "docsIf31CmDsOfdmChanSubcarrierZeroFreq": 847100000,
        "docsIf31CmDsOfdmChanFirstActiveSubcarrierNum": 1238,
        "docsIf31CmDsOfdmChanLastActiveSubcarrierNum": 2857,
        "docsIf31CmDsOfdmChanNumActiveSubcarriers": 1583,
        "docsIf31CmDsOfdmChanSubcarrierSpacing": 50,
        "docsIf31CmDsOfdmChanCyclicPrefix": 512,
        "docsIf31CmDsOfdmChanRollOffPeriod": 256,
        "docsIf31CmDsOfdmChanPlcFreq": 954000000,
        "docsIf31CmDsOfdmChanNumPilots": 29,
        "docsIf31CmDsOfdmChanTimeInterleaverDepth": 16,
        "docsIf31CmDsOfdmChanPlcTotalCodewords": 264684790,
        "docsIf31CmDsOfdmChanPlcUnreliableCodewords": 0,
        "docsIf31CmDsOfdmChanNcpTotalFields": 3387947050,
        "docsIf31CmDsOfdmChanNcpFieldCrcFailures": 0
      }
    },
    {
      "index": 49,
      "channel_id": 33,
      "entry": {
        "docsIf31CmDsOfdmChanChanIndicator": "nonPrimary",
        "docsIf31CmDsOfdmChanSubcarrierZeroFreq": 758600000,
        "docsIf31CmDsOfdmChanFirstActiveSubcarrierNum": 1148,
        "docsIf31CmDsOfdmChanLastActiveSubcarrierNum": 2947,
        "docsIf31CmDsOfdmChanNumActiveSubcarriers": 1761,
        "docsIf31CmDsOfdmChanSubcarrierSpacing": 50,
        "docsIf31CmDsOfdmChanCyclicPrefix": 512,
        "docsIf31CmDsOfdmChanRollOffPeriod": 256,
        "docsIf31CmDsOfdmChanPlcFreq": 861000000,
        "docsIf31CmDsOfdmChanNumPilots": 31,
        "docsIf31CmDsOfdmChanTimeInterleaverDepth": 16,
        "docsIf31CmDsOfdmChanPlcTotalCodewords": 264688869,
        "docsIf31CmDsOfdmChanPlcUnreliableCodewords": 0,
        "docsIf31CmDsOfdmChanNcpTotalFields": 3387999936,
        "docsIf31CmDsOfdmChanNcpFieldCrcFailures": 0
      }
    }
  ]
}

Channel Fields¶

Field	Type	Description
`index`	int	SNMP table index (OID instance) for this channel’s row in the CM table.
`channel_id`	int	DOCSIS downstream OFDM logical channel ID.
`entry`	obj	DS-OFDM configuration and counters for the channel (see next table for field details).

Entry Fields¶

Field	Type	Units	Description
`docsIf31CmDsOfdmChanChanIndicator`	string	—	Channel indicator (e.g., `primary`, `backupPrimary`, `nonPrimary`).
`docsIf31CmDsOfdmChanSubcarrierZeroFreq`	int	Hz	Frequency of subcarrier 0.
`docsIf31CmDsOfdmChanFirstActiveSubcarrierNum`	int	—	Index of the first active subcarrier.
`docsIf31CmDsOfdmChanLastActiveSubcarrierNum`	int	—	Index of the last active subcarrier.
`docsIf31CmDsOfdmChanNumActiveSubcarriers`	int	—	Count of active subcarriers.
`docsIf31CmDsOfdmChanSubcarrierSpacing`	int	kHz	Subcarrier spacing (typical downstream values are 25 or 50 kHz).
`docsIf31CmDsOfdmChanCyclicPrefix`	int	samp	Cyclic prefix length in samples.
`docsIf31CmDsOfdmChanRollOffPeriod`	int	samp	Roll-off (guard) period in samples.
`docsIf31CmDsOfdmChanPlcFreq`	int	Hz	PLC (Physical Link Channel) center frequency.
`docsIf31CmDsOfdmChanNumPilots`	int	—	Number of pilot subcarriers.
`docsIf31CmDsOfdmChanTimeInterleaverDepth`	int	sym	Time interleaver depth in OFDM symbols.
`docsIf31CmDsOfdmChanPlcTotalCodewords`	int	—	Total PLC codewords received.
`docsIf31CmDsOfdmChanPlcUnreliableCodewords`	int	—	PLC codewords flagged as unreliable.
`docsIf31CmDsOfdmChanNcpTotalFields`	int	—	Total NCP (Next Codeword Pointer) fields received.
`docsIf31CmDsOfdmChanNcpFieldCrcFailures`	int	—	NCP fields with CRC failures.

Notes¶

Useful for visualizing OFDM channel characteristics and error metrics for proactive diagnostics.
Ensure SNMP access to the modem’s ip_address from your collection host.
Field names align with DOCSIS-IF3-MIB DS-OFDM channel objects.