Definitions of Managed Objects for the ADSL Lines
Extracted elements (25)
Configuration parameters are stored only in physical-layer profile tables. Channel ifEntrys carry no configuration of their own; instead they use the ifStackTable to locate their parent physical-layer entry and inherit its configuration, avoiding duplication across channel types.
Separate parallel tables are defined for ATU-C and ATU-R rather than combined tables, because 'the tables are more easily read when there are two identical sets of data.' Since the SNMP agent co-resides with only one end of the line, far-end status objects may be incomplete when line errors prevent accurate reporting.
The MIB supports two profile implementation modes—MODE-I (dynamic, shared profiles managed via RowStatus) and MODE-II (static, one system-generated read-only profile per ADSL line)—but not both simultaneously. This accommodates large DSLAM deployments where shared profiles reduce provisioning burden as well as simpler single-line implementations.
ifLinkUpDownTrapEnable defaults to enabled(1) for the physical interface and disabled(2) for fast and interleaved channel interfaces. ifConnectorPresent defaults to true(1) for physical and false(2) for channel interfaces. ifPhysAddress should be a zero-length octet string. ifRcvAddressTable is not applicable for ADSL interfaces.
Implementation of the Entity MIB (RFC 2037) is optional and does not alter adslLineMib content or its IF-MIB relationship. If implemented, entAliasMappingTable should map ATU-C (or ATU-R) physical entities to their corresponding ifIndex values, and entPhysicalName approximates ifName semantics.
The ATU-R agent supports only a defined subset of the full MIB: it does not support adslLineConfProfileTable, and does not support adslAtucPerfLols/Lprs counters or their 15-minute and 1-day variants. ATU-R agents do support all adslAtur* tables and alarm profile tables except adslAtucThresh15MinLols/Lprs.
A threshold trap fires when the current 15-minute interval error counter becomes equal to or exceeds the configured threshold value. At most one trap is sent per 15-minute interval per interface; setting the threshold to 0 disables the trap.
Counters are NOT reset when an ATU-C or ATU-R is reinitialized; they are only reset when the agent itself is reset or reinitialized, or under specific request outside the scope of this MIB.
In MODE-I (dynamic profiles), implementations must provide a default profile named 'DEFVAL' for each profile type (Configuration and Alarm). Lines not yet explicitly configured are automatically assigned this profile via adslLineConfProfile and adslLineAlarmConfProfile.
Required SNMP traps include: coldStart/warmStart per agent (e.g., per DSLAM) and linkUp/linkDown per physical-layer interface. A linkDown trap must be generated whenever Lof, Los, Lol, Loss of Signal Quality, or Lpr occurs; the corresponding linkUp is sent when all link failure conditions clear.
The MIB module is compliant to SMIv2. Implementors may produce an SMIv1-conformant MIB via translation, but Counter64 objects cannot be translated and some machine-readable information will be lost; such translation does not change the semantic equivalence of the MIB.
The rate-change trap fires when currTxRate >= prevTxRate + ThreshRateUp or currTxRate <= prevTxRate - ThreshRateDown. No trap is sent on initialization. PrevTxRate is set to the current value at initialization and each time a trap is sent, so rate changes accumulate until the threshold is crossed.
adslAtucCurrStatus is a BITS object with 10 positions indicating current ATU-C defect conditions: noDefect(0), lossOfFraming(1), lossOfSignal(2), lossOfPower(3), lossOfSignalQuality(4) (triggered when SNR margin falls below minimum or BER exceeds 10^-7), lossOfLink(5), dataInitFailure(6), configInitFailure(7), protocolInitFailure(8), noPeerAtuPresent(9). The ATU-R counterpart has only bits 0-4.
AdslLineCodingType is a textual convention enumerating ADSL line codes: other(1), dmt(2) for Discrete MultiTone, cap(3) for Carrierless Amplitude and Phase modulation, and qam(4) for Quadrature Amplitude Modulation.
adslLineType encodes five ADSL operational configurations: noChannel(1), fastOnly(2), interleavedOnly(3), fastOrInterleaved(4) (at most one channel type active at any time, manager-selectable), and fastAndInterleaved(5) (both channels coexist). The physical ifEntry always exists; channel ifEntrys exist only when the corresponding channel type is configured.
Channel performance tables (adslAtuc/AturChanPerfDataTable and corresponding interval tables) track total received blocks, corrected blocks, uncorrectable blocks, and transmitted blocks at the channel level, using the same 15-minute and 1-day bucket structure as physical-layer tables.
Performance data tables (adslAtucPerfDataTable, adslAturPerfDataTable) maintain cumulative counters since agent reset (Lofs, Loss, Lols, Lprs, ESs, Inits), plus current 15-minute bucket counters (PerfCurrentCount), up to 96 historical 15-minute interval buckets (PerfIntervalCount), and current and previous 1-day counters (AdslPerfCurrDayCount / AdslPerfPrevDayCount).
The ADSL LINE MIB defines two modules: ADSL-TC-MIB (OID transmission.94.2) providing textual conventions, and ADSL-LINE-MIB (OID transmission.94) providing all managed objects. Both are SMIv2-compliant and rooted under the IANA-assigned transmission.94 arc.
The adslAtucChanTable and adslAturChanTable (indexed by ifIndex where ifType is adslInterleave(124) or adslFast(125)) expose: interleaveDelay in milliseconds (noSuchObject for fast channel), currTxRate in bps, prevTxRate in bps (updated at each rate-change trap and at initialization), and crcBlockLength in bytes.
The adslAtucPhysTable and adslAturPhysTable each expose per-ATU physical-layer parameters: inventory fields (serial number up to 32 chars, vendor ID up to 16 chars, version number up to 16 chars), adslAtu*CurrSnrMgn in tenth dB (range -640..640), adslAtu*CurrAtn in tenth dB (0..630), adslAtu*CurrOutputPwr in tenth dBm (-310..310), and adslAtu*CurrAttainableRate in bps.
The adslLineTable (indexed by ifIndex, ifType=adsl(94)) contains per-line common attributes: adslLineCoding (AdslLineCodingType), adslLineType (noChannel/fastOnly/interleavedOnly/fastOrInterleaved/fastAndInterleaved), adslLineSpecific (OID pointer to vendor MIB for shelf/slot/port), adslLineConfProfile, and adslLineAlarmConfProfile.
Three ADSL interface layers exist per line: a mandatory physical interface (ifType=adsl(94)), an optional fast channel (ifType=adslFast(125)), and an optional interleaved channel (ifType=adslInterleave(124)). The ifStackTable relates channel entries to their parent physical-layer entry so that configuration profile parameters can be inherited.
Two profile table types are defined: adslLineConfProfileTable for configuration parameters and adslLineAlarmConfProfileTable for alarm thresholds. Profiles are referenced by name (SnmpAdminString, 1..32 chars) from adslLineTable via adslLineConfProfile and adslLineAlarmConfProfile.
IANA assigned three ifType values for ADSL interfaces: adsl(94) for the physical interface, adslInterleave(124) for the interleaved channel, and adslFast(125) for the fast channel. These ifType values index all MIB tables in this document.
The ADSL LINE MIB contains read-write objects (adslLineConfProfile, adslLineAlarmConfProfile, and profile table entries) whose unauthorized modification could disrupt ADSL line operation or suppress alarms. The security considerations section recommends restricting write access using SNMPv3 with authentication and privacy, as the MIB was designed for SNMPv2c/v3 environments.