Definitions of Managed Objects for High Bit-Rate DSL - 2nd generation (HDSL2) and Single-Pair High-Speed Digital Subscriber Line (SHDSL) Lines Processing
obsoleted by
- rfc-4319 — Definitions of Managed Objects for High Bit-Rate DSL - 2nd generation (HDSL2) and Single-Pair High-Speed Digital Subscriber Line (SHDSL) Lines
Extracted elements (26)
Invalid interval buckets result in holes in interval tables rather than placeholder rows. For example, if interval 12 is invalid but 11 and 13 are valid, a GetNext on .1.1.1.1.11 returns .1.1.1.1.13. This differs from RFC 2493 and RFC 2662 which represented invalid buckets explicitly.
SNR Margin and Loop Attenuation alarm conditions are tracked per-endpoint in the MIB rather than per-unit as in the EOC specification. For repeaters this requires the terminal unit agent to detect threshold crossings, but since the EOC reports SNR/attenuation values in the same message as alarm conditions, the implementation impact is minimal.
The MIB uses profiles to simplify provisioning of large numbers of lines. A profile is a set of parameters shared by multiple lines, so changing one profile reconfigures all referencing lines simultaneously rather than requiring per-line management.
The MIB is specified as SMIv2-compliant. A translation to SMIv1-conforming MIB is possible except where Counter64 objects are used, which cannot be translated and will be omitted from the SMIv1 version.
Any attempt to set hdsl2ShdslEndpointAlarmConfProfile to a value that is not the index of an active entry in hdsl2ShdslEndpointAlarmConfProfileTable MUST be rejected.
Any attempt to set hdsl2ShdslSpanConfProfile to a value that is not the index of an active entry in hdsl2ShdslSpanConfProfileTable MUST be rejected. HDSL2 lines MUST reference the default profile 'DEFVAL'.
Counters are not reset when an xU is reinitialized; they are only reset when the agent itself is reset or reinitialized, or under specific external request outside the scope of this MIB.
For both HDSL2 and SHDSL lines, the following MIB groups are mandatory: hdsl2ShdslSpanConfGroup, hdsl2ShdslSpanStatusGroup, hdsl2ShdslInventoryGroup, hdsl2ShdslEndpointConfGroup, hdsl2Shdsl15MinIntervalGroup, hdsl2Shdsl1DayIntervalGroup, hdsl2ShdslMaintenanceGroup, hdsl2ShdslEndpointAlarmConfGroup, and hdsl2ShdslNotificationGroup.
If an active profile entry is referenced in hdsl2ShdslSpanConfProfile or hdsl2ShdslEndpointAlarmConfProfile, the entry MUST remain active until all references are removed before it can be deleted.
Implementations MUST provide a default profile named 'DEFVAL' for each profile type. The name 'DEFVAL' is reserved in the context of profiles defined in this MIB.
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 implementing this MIB MUST be persistent. This applies to the span configuration table, endpoint configuration table, and other ifIndex-indexed tables.
The ifFixedLengthGroup from RFC 2863 MUST be supported by implementations of this MIB. The ifRcvAddressGroup does not apply to this MIB.
The ifPhysAddress object for HDSL2/SHDSL interfaces MUST have an octet string with zero length.
When interval data is suspect or known to be invalid, the agent MUST NOT report the interval. If the current 15-minute event bucket is determined to be invalid, notifications based on its value MUST NOT be generated.
A threshold notification is generated when the current 15-minute interval error counter becomes equal to or exceeds the threshold value. At most one notification may be sent per interval per interface. Setting a threshold to 0 disables the notification; setting it to 1 generates a notification on the first occurrence.
Performance monitoring uses three time granularities: current 15-minute intervals (up to 96 historical buckets covering 24 hours), current 1-day intervals (up to 30 historical buckets covering 30 days), and cumulative counters since last xU restart. Metrics tracked include ES, SES, CRC anomalies, LOSW seconds, and UAS.
The Hdsl2ShdslClockReferenceType convention enumerates four STU-C symbol clock references: localClk(1)/Mode-1, networkClk(2)/Mode-2, dataOrNetworkClk(3)/Mode-3a, and dataClk(4)/Mode-3b, per ITU G.991.2.
The hdsl2ShdslEndpointCurrStatus object is a BITS construct representing all outstanding error conditions at a segment endpoint, including: noDefect, powerBackoff, deviceFault, dcContinuityFault, snrMarginAlarm, loopAttenuationAlarm, loswFailureAlarm, configInitFailure, protocolInitFailure, noNeighborPresent, and loopbackActive.
The hdsl2ShdslMaintSoftRestart object supports two states: ready(1) and restart(2). A manager may only set the value to restart(2); the agent performs the restart after approximately 5 seconds and then restores the object to ready(1).
The hdsl2ShdslSpanInvalidNumRepeaters notification is generated after discovery if the number of discovered repeaters differs from hdsl2ShdslSpanConfNumRepeaters. Excess provisioned-but-absent repeater entries are discarded; excess discovered-but-unprovisioned repeater entries are created using the default span configuration profile.
The Hdsl2ShdslTransmissionModeType textual convention is a BITS construct with region1(0) indicating ITU-T G.991.2 Annex A and region2(1) indicating ITU-T G.991.2 Annex B, representing the regional PSD setting of the span.
The Hdsl2ShdslUnitId textual convention uniquely identifies units in a span using the EOC addressing scheme: xtuC(1), xtuR(2), and xru1(3) through xru8(10) for up to 8 regenerators numbered from the central office side.
The HDSL2-SHDSL-LINE-MIB module is assigned object identifier transmission(48) in the SNMPv2-SMI MIB module. IANA allocated this OID for the MODULE-IDENTITY. Additionally, IANA assigned ifType values hdsl2(168) and shdsl(169) to represent the two interface types.
Several MIB objects have read-write or read-create access and could be used to disrupt service: hdsl2ShdslMaintLoopbackConfig can initiate loopbacks, hdsl2ShdslMaintSoftRestart can restart modems, hdsl2ShdslSpanConfNumRepeaters can corrupt span topology, and profile objects can alter all lines sharing that profile. SNMPv3 with authentication and privacy is recommended to prevent unauthorized access.
Inventory table entries follow a dynamic lifecycle: created during line discovery when an xtu discovers a far-end xtu or xru; destroyed when the line goes down and devices become unreachable via EOC. These entries are NOT persistent.