Definitions of Managed Objects for Very High Speed Digital Subscriber Lines (VDSL)
Extracted elements (29)
Counters are not reset when a Vtu is reinitialized; they are only reset when the agent itself is reset or reinitialized (or via a specific out-of-band request). This preserves long-term performance history across line flaps.
Profiles are used to simplify provisioning of large numbers of VDSL lines (potentially hundreds or thousands). Most lines share identical configuration; a single profile change propagates to all associated lines simultaneously, avoiding per-line reconfiguration.
The MIB uses HC-PerfHist-TC-MIB (RFC 3705) textual conventions — 64-bit versions of the RFC 3593 types — for all interval counters. This prevents counter wrap on high-speed VDSL lines where 32-bit counters could overflow within a 15-minute interval.
There is no requirement for an agent to align 15-minute intervals with wall-clock quarter hours, though implementations MAY do so. Similarly, 1-day intervals MAY be aligned with the start of a day. This avoids mandating clock synchronization for basic performance management.
A VDSL line supporting both fast and interleaved channels requires three ifTable entries: one for the physical line (ifType=97), one for fast (ifType=125), and one for interleaved (ifType=124). The ifStackTable is used to represent the stacking relationship between these entries.
IANA has assigned ifType vdsl(97) for the physical VDSL line, interleave(124) for the optional interleaved channel, and fast(125) for the optional fast channel. All three integrate into IF-MIB (RFC 2863) via ifTable.
All read-write and read-create objects defined in this MIB module SHOULD be stored persistently, including all profile configuration objects and alarm threshold objects. Interface indices and associated VACM data SHOULD also be stored persistently.
Entries in vdslLineConfProfileTable MUST be maintained in a persistent manner.
Implementations MUST provide a default profile named 'DEFVAL' for each profile type. This name is reserved; its parameter values are vendor-specific unless otherwise specified.
Profile changes MUST take effect immediately. These changes MAY result in a restart (hard reset or soft restart) of the units on the line.
Table entries indexed by ifIndex for interfaces in systems implementing this MIB MUST be persistent.
The ability to generate coldStart/WarmStart (per RFC 3418) and linkUp/linkDown (per RFC 2863) notifications is required. A linkDown notification MAY be generated whenever any of lof, lol, los, lpr, ES, SES, or UAS threshold crossing occurs.
The ifPhysAddress object for VDSL interfaces MUST have an octet string with zero length.
vdslLineConfProfile and vdslLineAlarmConfProfile objects MUST each be maintained in a persistent manner.
The VDSL-LINE MIB is rooted at transmission(97) and organized into vdslGroup (line-code-independent tables for ifType vdsl(97)) and vdslNotificationGroup. Both groups are mandatory for conforming implementations.
Threshold notifications fire when a current 15-minute interval error counter becomes equal to or exceeds the configured threshold value. At most one notification is sent per interval per interface; counters reset to 0 every 15 minutes, so a persistent condition may re-notify as often as every 15 minutes.
vdslChanPerfDataTable provides per-channel counters including vdslChanFixedOctets (corrected octets, ZeroBasedCounter64) and vdslChanBadBlks (uncorrectable blocks, ZeroBasedCounter64), plus 15-minute and 1-day current-interval equivalents using HCPerfCurrentCount.
vdslChanTable (indexed by ifIndex and vdslPhysSide, applicable to ifType interleave(124) and fast(125)) exposes per-channel parameters: interleave delay (ms), CRC block length (bytes), current TX rate (kbps), burst protection (microseconds, interleaved only), and FEC overhead (%, fast only).
vdslLineAlarmConfProfileTable defines per-Vtu alarm thresholds for 15-minute intervals: Lofs, Loss, Lprs, Lols, ESs, SESs, UASs, and an initialization failure flag. A threshold value of 0 disables the corresponding notification.
VdslLineCodingType is a textual convention encoding the line coding as INTEGER: other(1), mcm(2) for Multiple Carrier Modulation, or scm(3) for Single Carrier Modulation.
vdslLineConfProfileTable holds line configuration profiles indexed by vdslLineConfProfileName (SnmpAdminString, 1–32 octets). Profile parameters include downstream/upstream rate mode, max power, SNR margins (target/min/max), data rates for fast and slow channels, interleave delay, PBO control, deployment scenario, band plan, PSD templates, HAM band mask, and custom notch filters.
VdslLineEntity is a textual convention identifying which transceiver is referenced: vtuc(1) for the central-site unit or vtur(2) for the remote-site unit. This index is used throughout the physical, performance, and channel tables.
vdslLineTable (indexed by ifIndex) holds line-wide attributes including vdslLineCoding, vdslLineType (noChannel/fastOnly/interleavedOnly/fastOrInterleaved/fastAndInterleaved), vdslLineConfProfile, and vdslLineAlarmConfProfile.
vdslPerf1DayIntervalTable stores up to 30 historical 1-day interval buckets per Vtu (interval 1 = most recent day; interval 30 = 30 days ago); intervals 2–30 are optional. This table is NOT persistent as it contains live equipment data.
vdslPerfDataTable provides cumulative and current-interval counters per Vtu for Lofs, Loss, Lprs, Lols, ESs, SESs, UASs, and Inits, using HC-PerfHist-TC-MIB types (HCPerfCurrentCount, HCPerfTimeElapsed) for the 15-minute and 1-day current intervals.
vdslPerfIntervalTable stores up to 96 historical 15-minute interval buckets per Vtu (interval 1 = most recent; interval 96 = 24 hours ago); intervals 2–96 are optional. Each bucket uses HCPerfIntervalCount for Lofs, Loss, Lprs, Lols, ESs, SESs, UASs, and Inits.
vdslPhysCurrStatus is a BITS object representing up to 10 simultaneous fault conditions: noDefect(0), lossOfFraming(1), lossOfSignal(2), lossOfPower(3), lossOfSignalQuality(4), lossOfLink(5), dataInitFailure(6), configInitFailure(7), protocolInitFailure(8), noPeerVtuPresent(9). It supplements ifOperStatus.
vdslPhysTable (indexed by ifIndex and vdslPhysSide) provides per-Vtu physical layer parameters including SNR margin (Integer32, units 0.25 dBm), attenuation (Gauge32, units 0.25 dBm), output power (Integer32, units 0.1 dBm), attainable rate, and current line rate in kbps.
The MIB contains read-write and read-create objects (profile configuration, alarm thresholds) that can directly affect VDSL line operation, including forcing line restarts. Unauthorized write access could disrupt service; implementations should apply SNMPv3 authentication and access control (VACM) to protect these objects.