Radio Frequency (RF) Interface Management Information Base for Data over Cable Service Interface Specifications (DOCSIS) 2.0 Compliant RF Interfaces
obsoletes
- rfc-2670 — Radio Frequency (RF) Interface Management Information Base for MCNS/DOCSIS compliant RF interfaces
updated by
- rfc-9141 — Updating References to the IETF FTP Service
Extracted elements (27)
A new ifType value docsCableUpstreamChannel(205) was introduced for DOCSIS 2.0 to model upstream logical channels (A-TDMA and S-CDMA) as a distinct layer beneath the physical upstream interface (ifType 129), enabling the ifStackTable to represent the multi-channel upstream architecture while preserving backward compatibility with DOCSIS 1.x.
docsIfQosProfileTable is defined as a separate table—rather than embedding QoS parameters inline in the service tables—to avoid duplicating profile data across multiple service flow entries that share the same class of service.
The offline upstream parameter handling mechanism uses temporary row entries so that a group of interdependent upstream channel parameters (modulation profile, channel type, slot size, S-CDMA attributes) can be validated for mutual consistency before being atomically committed to the in-service physical interface, minimizing channel outage windows.
For DOCSIS 2.0 CMTSs, upstream logical channels use ifType docsCableUpstreamChannel(205) and are stacked below the upstream physical interface (ifType 129); DOCSIS 1.x CM/CMTS and DOCSIS 2.0 CMs use only ifType 129 with entries directly in docsIfUpstreamChannelTable.
Section 7 addresses management interoperability across DOCSIS 1.0, 1.1, and 2.0; the DocsisQosVersion convention distinguishes Class of Service (docsis10) from Quality of Service (docsis11) queuing models, which affects how docsIfQosProfileTable and service tables are populated and interpreted.
The docsIfDownChannelInterleave value taps12increment17(8) (protection 18/14 µs, latency 0.43/0.32 ms) is exclusive to Euro-DOCSIS cable systems; all other interleave values apply to standard DOCSIS systems.
An entry in docsIfQosProfileTable MUST NOT be removed while it is referenced by an entry in docsIfCmServiceTable (CM) or docsIfCmtsServiceTable (CMTS).
docsIfUpChannelCloneFrom MUST contain zero for physical interface entries; setting it on a physical interface row returns the error 'wrongValue'.
For docsIfUpChannelScdmaActiveCodes, legal integer values in the range 64..128 MUST be non-prime; the object syntax enumerates only the permitted non-prime values.
Setting docsIfUpChannelModulationProfile returns 'inconsistentValue' unless all IUC entries in the selected modulation profile share the same docsIfCmtsModChannelType value AND all modulation parameters are mutually consistent with the upstream channel entry.
Temporary upstream interface rows MUST be set to 'active' via docsIfUpChannelStatus to validate parameter consistency before committing to the physical interface; if parameters are incompatible, the SET returns 'commitFailed'.
The ifStackTable (RFC 2863) MUST be implemented to identify the layering relationships among sub-interfaces: the RF MAC layer sits above downstream and upstream interfaces, and upstream interfaces sit above upstream logical channels.
docsIfCmtsChannelUtilizationTable provides statistical load usage data for attached upstream and downstream physical channels; docsIfCmtsDownChannelCounterTable and docsIfCmtsUpChannelCounterTable provide per-channel packet and octet counters as inputs to utilization calculations.
docsIfCmtsCmStatusTable holds per-CM status information for all known CMs (ranging, registered, and/or previously online) from the CMTS perspective, complementing the CM-side docsIfCmStatusTable.
docsIfCmtsModulationTable allows CMTS control over modulation burst profiles for upstream RF channels; each entry is instantiated by interval usage codes (IUCs) that together fully define the channel modulation for a given profile index.
docsIfDocsisBaseCapability (docsIfBaseObjects) indicates the highest DOCSIS version the cable device supports using the DocsisVersion textual convention {docsis10(1), docsis11(2), docsis20(3)}.
docsIfDownstreamChannelTable (docsIfBaseObjects 1) describes per-downstream-channel attributes indexed by ifIndex: center frequency, channel width, modulation (QAM64/QAM256), FEC interleave depth, transmit/receive power in TenthdBmV, and ITU-T J.83 Annex indicator (A/B/C).
docsIfQosProfileTable (docsIfBaseObjects 3) describes QoS/COS profiles referenced by CM and CMTS service tables; entries are either read-create (CMTS-managed) or read-only (populated from REG-REQ MAC messages or TFTP option files).
docsIfSignalQualityTable monitors RF signal quality characteristics of received signals and is implemented on both CM and CMTS interfaces.
docsIfUpstreamChannelTable (docsIfBaseObjects 2) describes upstream channel attributes for both physical interfaces (ifType 129 or 205) and temporary offline-editing interfaces, covering frequency, width, modulation profile index, slot size, SCDMA parameters (active codes, codes-per-slot, frame size, hopping seed), channel type, and pre-equalization enable.
This document defines the DOCS-IF-MIB module registered at OID { transmission 127 }, obsoleting RFC 2670. It introduces new textual conventions DocsisVersion, DocsisQosVersion, DocsisUpstreamType, and DocsEqualizerData, and adds DOCSIS 2.0 MIB objects for S-CDMA parameters, channel utilization counters, and offline upstream configuration.
Deployment of SNMP versions prior to SNMPv3 is not recommended for managing this MIB module, as SNMPv1 and SNMPv2c provide no message-level authentication or confidentiality protection for sensitive RF configuration operations.
This MIB contains numerous read-write and read-create objects controlling downstream frequency, upstream channel parameters, modulation profiles, and power levels; unauthorized writes could disrupt cable service for large subscriber populations. SNMPv3 with authentication and privacy is strongly recommended.
The offline upstream parameter update state machine: (1) SET docsIfUpChannelStatus='createAndWait' → status becomes 'notReady'; (2) SET docsIfUpChannelCloneFrom=physical ifIndex → parameters copied, status becomes 'notInService'; (3) modify parameters in temporary row; (4) SET status='active' to validate (returns 'commitFailed' if invalid); (5) SET docsIfUpChannelUpdate='true' to commit to physical interface; (6) SET status='destroy' to remove temporary row.
DocsEqualizerData encodes DOCSIS RFI transmit equalization data as OCTET STRING (SIZE 0 | 36..260): a 4-byte header (main tap location, forward taps per symbol, number of forward taps n, number of reverse taps m) followed by n+m complex coefficients each as two signed 16-bit integers (real, imaginary), supporting up to 64 taps (max 260 bytes).
DocsisUpstreamType encodes upstream channel modulation mode as INTEGER: unknown(0), tdma(1), atdma(2), scdma(3), tdmaAndAtdma(4), covering all DOCSIS 1.0 (TDMA) and 2.0 (A-TDMA, S-CDMA) upstream types.
TenthdBmV is an Integer32 textual convention (DISPLAY-HINT 'd-1') encoding power in tenths of dBmV (e.g., 5.1 dBmV = 51). TenthdB encodes signal level ratios in tenths of dB with the same representation.