Definitions of Extension Managed Objects for Asymmetric Digital Subscriber Lines
Extracted elements (23)
Performance counters are not reset on ATU-C or ATU-R reinitialization — only on agent reset or reinitialization. This ensures continuity of performance data across link-layer events, which are frequent in ADSL operation.
Unavailable seconds-line (UasL) explicitly excludes seconds caused solely by fast retrains and failed fast retrains, because fast retrains are considered normal network operation rather than availability failures. This prevents the UasL counter from being inflated by routine G.Lite link maintenance events.
For static profile implementations, threshold objects (adslAtucThreshold15MinFailedFastR, etc.) are read-write rather than read-create, and adslLineConfProfileDualLite is read-only (algorithmically set). For dynamic profile implementations, these objects are read-create and the profile index is manager-set.
There is no requirement for an agent to align 15-minute interval boundaries with wall-clock quarter hours, though implementations may do so. Similarly, 1-day intervals may optionally align with midnight. Implementations must not assume fixed-boundary alignment when correlating counters across devices.
The compliance statement (adslExtLineMibAtucCompliance) requires three mandatory groups: adslExtLineGroup, adslExtLineConfProfileControlGroup, and adslExtLineAlarmConfProfileGroup. ATU-C/ATU-R physical performance counter groups and the notifications group are optional.
The value of ifOperStatus (RFC 2863) SHALL be down(2) when the ADSL line interface is in G.Lite power state L3 (no power), and shall be up(1) for power states L0 or L1. Power state L2 is not applicable.
adslConfProfileLineType (in adslConfProfileExtTable augmenting adslLineConfProfileEntry) configures the ADSL physical line channel mode with values: noChannel(1), fastOnly(2), interleavedOnly(3), fastOrInterleaved(4), fastAndInterleaved(5). Default is fastOnly(2).
adslLineConfProfileDualLite is used only when adslLineTransAtucConfig is set to both one or more full-rate and one or more G.Lite modes simultaneously (dual mode). For dynamic profiles its value equals the applicable row index in AdslLineConfProfileTable; for static profiles it is a fixed-length 14-character string concatenating ifIndex (zero-padded) with 'Full' or 'Lite'.
adslLineTransAtucActual returns the single transmission mode negotiated during ADSL line initialization; the ATU-R determines the mode. It returns 0 (no bit set) if the mode is unknown, and persists as the 'current' mode if the link goes down.
Five SNMP NOTIFICATION-TYPEs are defined: adslAtucFailedFastRThreshTrap, adslAtucSesLThreshTrap, adslAtucUasLThreshTrap (ATU-C side), and adslAturSesLThreshTrap, adslAturUasLThreshTrap (ATU-R side), each fired the first time the corresponding 15-minute counter reaches or exceeds its configured threshold within a collection period.
The ADSL-LINE-EXT-MIB module (adslExtMIB) is defined as a supplement to the ADSL-LINE-MIB (RFC 2662), rooted at adslMIB 3. It adds managed objects for transmission mode control, G.Lite power state, fast retrain counters, severely errored seconds-line, unavailable seconds-line, line mode profiles, and alarm thresholds.
The adslAlarmConfProfileExtTable augments adslLineAlarmConfProfileEntry with five threshold objects: adslAtucThreshold15MinFailedFastR, adslAtucThreshold15MinSesL, adslAtucThreshold15MinUasL, adslAturThreshold15MinSesL, and adslAturThreshold15MinUasL, each Integer32(0..900) seconds with default 0 (disabled).
The adslAtucIntervalExtTable augments adslAtucIntervalEntry with four per-interval counters (FastR, FailedFastR, SesL, UasL) of type PerfIntervalCount, providing up to 96 historical 15-minute buckets for the ATU-C end.
The adslAtucPerfDataExtTable augments adslAtucPerfDataEntry with 16 counters tracking fast retrains (FastR), failed fast retrains (FailedFastR), severely errored seconds-line (SesL), and unavailable seconds-line (UasL) across four time periods: cumulative since agent reset, current 15-minute, current 1-day, and previous 1-day.
The adslAturIntervalExtTable augments adslAturIntervalEntry with two per-interval counters (SesL, UasL) of type PerfIntervalCount for ATU-R 15-minute history buckets.
The adslAturPerfDataExtTable augments adslAturPerfDataEntry with 8 counters for SesL and UasL across cumulative, current 15-minute, current 1-day, and previous 1-day intervals for the ATU-R end. Note: fast retrain counters are not defined for ATU-R.
The adslLineExtTable augments adslLineEntry (RFC 2662) with five objects: adslLineTransAtucCap (read-only capability bitmask), adslLineTransAtucConfig (read-write enabled modes), adslLineTransAtucActual (read-only current mode, single bit), adslLineGlitePowerState (read-only power state), and adslLineConfProfileDualLite (read-write dual-mode profile name).
The AdslTransmissionModeType textual convention is a BITS string encoding 13 ADSL transmission modes (bits 0–12), distinguishing Full-Rate modes (ANSI T1.413, ETSI, G.992.1 variants) from G.Lite modes (G.992.2 variants). Multiple bits may be set simultaneously to indicate capability or configuration.
ATU-R connectivity from the subscriber side allows manipulation of the ADSL link and the overhead/embedded operations channel (AOC/EOC). Unchecked subscriber-initiated fluctuations could generate notification floods sufficient to overwhelm the management interface or element manager.
For static profiles, adslLineConfProfileDualLite is algorithmically derived from ifIndex and not guaranteed to be stable across system reboots. Implementors must ensure that profile object values associated with these indices are maintained across reboots, consistent with adslLineConfProfile handling in RFC 2662.
SNMPv1 provides no access control even on a secure network; implementors are recommended to use SNMPv3 with the User-based Security Model (RFC 3414) and the View-based Access Control Model (RFC 3415) to restrict object access to authorized principals.
Unauthorized write access to MIB profile objects (Section 6.4) can alter subscriber service characteristics (rate partitioning, maximum transmission rates) and network operations (notification thresholds such as SNR margins). Access control via the element management system is outside this document's scope.
G.Lite power state machine has three states: L0 (power on), L1 (power on but reduced), and L3 (power off). Transitions are not operator-configurable. L3 maps to ifOperStatus down(2); L0 and L1 map to ifOperStatus up(1). The adslLineGlitePowerState object reports none(1) when the interface is not operating in a G.992.2 mode.