Definitions of Managed Objects for the DS3/E3 Interface Type
obsoleted by
- rfc-2496 — Definitions of Managed Object for the DS3/E3 Interface Type
obsoletes
- rfc-1233 — Definitions of managed objects for the DS3 Interface type
Extracted elements (28)
A boundary condition exists when the 10-second unavailability determination window crosses the 900-second statistics interval boundary: successive GETs of dsx3IntervalPSESs and dsx3IntervalUASs may return differing values. This is documented as an unavoidable side-effect of the chosen managed-object design.
All Counters from RFC 1233 were changed to Gauges. Performance parameters that accumulate over a fixed interval and are then reset require Gauge semantics under SNMPv1 SMI rather than the monotonically-increasing Counter type.
RFC 1407 entirely replaces RFC 1233 because RFC 1233 contains a fundamental error: many objects were encoded as Counters that must be encoded as INTEGERs or Gauges. The magnitude of change required meant virtually every object changed, so RFC 1233 should not be implemented.
Separate P-bit (PES, PSES, PCV) and C-bit (CES, CSES, CCV) near-end counters were introduced to achieve symmetry with the far-end statistics available via C-bits in C-bit Parity and SYNTRAN applications. The original ES and SES counters were renamed to PES and PSES to reflect their P-bit basis.
The MIB was intentionally designed to closely align with objects that can generally be read from currently-deployed DS3/E3 devices, facilitating common management across all such devices rather than attempting to cover all possible management scenarios.
When an SNMP agent represents both a host and a DS3/E3 device (external+internal scenario), dsx3LineIndex values greater than ifNumber are assigned, with even numbers for inside (equipment-side) interfaces and odd numbers for outside (network-side) interfaces.
Implementation of the DS3/E3 Near End Group is mandatory for all systems that attach to a DS3/E3 Interface. It consists of four tables: Configuration, Current, Interval, and Total.
The DS3/E3 Fractional Group is optional and is intended for systems dividing a DS3/E3 into sub-channels carrying different data streams that are mapped to separate logical interfaces.
The DS3 Far End Group is optional and may only be implemented by DS3 systems that use C-bit Parity or SYNTRAN framing; it is not applicable to M23, ClearChannel, or E3 interfaces.
All performance parameters are accumulated in 15-minute intervals; up to 96 intervals (24 hours) are retained per interface. Fewer than 96 intervals are available if the agent was restarted within the last 24 hours. A rolling 24-hour total is also maintained. No requirement exists for aligning intervals with wall-clock quarter-hours.
DS3 AIS defect is declared after AIS is present in contiguous M-frames for time T (0.2 ms ≤ T ≤ 100 ms) and terminated after AIS is absent for the same duration T. E3 AIS is a continuous stream of ones; AIS detection and consequent actions must complete within 1 ms.
DS3 LOS defect is declared after 175±75 contiguous pulse positions with no pulses of either polarity; cleared upon observing an average pulse density of at least 33% over 175±75 contiguous positions starting with receipt of a pulse.
DS3 OOF defect is detected when 3 or more errors occur in 16 or fewer consecutive F-bits within a DS3 M-frame; cleared upon reframe. LOF failure is declared when OOF persists 2–10 seconds; cleared when OOF is absent for 10–20 seconds. E3 OOF requires 4 consecutive incorrect frame alignment signals.
dsx3LineCoding (read-write INTEGER) describes the zero-code suppression scheme: dsx3B3ZS or e3HDB3, which substitute patterns of normal bits and bipolar violations for zero sequences of specified lengths.
dsx3LineStatus is a read-only bit-map integer (1..1023) that can represent multiple simultaneous states: NoAlarm(1), RcvRAIFailure(2), XmitRAIAlarm(4), RcvAIS(8), XmitAIS(16), LOF(32), LOS(64), LoopbackState(128), RcvTestCode(256), OtherFailure(512). dsx3NoAlarm must be set if and only if no other flag is set.
dsx3LineType (read-write INTEGER) identifies the DS3/E3 application: dsx3M23, dsx3SYNTRAN, dsx3CbitParity, dsx3ClearChannel (C-bits used only for AIS), e3other, e3Framed, or e3Plcp. DS3 operates at 44.736 Mbps; E3 at 34.368 Mbps.
dsx3LoopbackConfig (read-write) specifies loopback state: dsx3NoLoop, dsx3PayloadLoop (signal looped after framing), dsx3LineLoop (signal looped with minimum penetration), or dsx3OtherLoop. Devices incapable of loopback must always return dsx3NoLoop.
dsx3SendCode (read-write) indicates the code being sent on the interface: NoCode, LineCode (request line loopback), PayloadCode (request payload loopback of all DS1/E1s), ResetCode (deactivate loopback), DS1LoopCode (loopback a specific DS1/E1), or TestPattern. These options are optional for E3 interfaces.
dsx3TransmitClockSource (read-write) identifies the transmit clock source as loopTiming (derived from the recovered receive clock of another DS3 interface), localTiming, or throughTiming.
Line Coding Violation (LCV) counts both Bipolar Violations (BPVs) and Excessive Zeros (EXZs): for B3ZS, EXZ is any zero string of length ≥3; for HDB3, length >4. An EXZ increments LCV by exactly one regardless of zero string length.
The DS3/E3 Current table (dsx3CurrentTable) holds 11 Gauge counters for the ongoing 15-minute interval: PESs, PSESs, SEFSs, UASs, LCVs, PCVs, LESs, CCVs, CESs, and CSESs. The Interval table (dsx3IntervalTable) mirrors these for each of up to 96 prior intervals, indexed by line and interval number (1=most recent, 96=oldest).
The DS3/E3 Fractional table (dsx3FracTable) maps individual channels to logical interfaces via dsx3FracIfIndex. DS3 applications (M23, SYNTRAN, CbitParity, ClearChannel) support 28 channels (1–28); e3Framed supports 16 channels (1–16) corresponding directly to time-slots. A channel with no interface assigned has dsx3FracIfIndex=0.
The DS3 Far End Configuration table carries identification strings transmitted in the Path Identification Message via C-bits: EquipCode (≤10 chars), LocationIDCode (≤11 chars), FrameIDCode (≤10 chars), UnitCode (≤6 chars), and FacilityIDCode (≤38 chars). All are read-write.
The DS3 Far End statistics group tracks four Gauge counters derived from the far-end block error count in the C-bits: CESs, CSESs, CCVs, and UASs — available only for C-bit Parity and SYNTRAN DS3 interfaces.
Two distinct indices are defined: dsx3IfIndex (always equal to ifIndex from MIB-II Interfaces table) and dsx3LineIndex (identifies a specific physical DS3/E3 line, which may differ from ifIndex when a single DS3 data stream traverses two interfaces, as on a CSU).
Several objects in this MIB have read-write ACCESS, including dsx3LineType, dsx3LineCoding, dsx3SendCode, dsx3LoopbackConfig, dsx3TransmitClockSource, and all far-end identification code objects. Unauthorized write access to these objects could disrupt DS3/E3 interface operation or alter the physical transmission configuration of the managed device.
An incoming failure state (LOS, OOF, or AIS) is declared when the defect persists for 2–10 seconds and cleared when the defect is absent for ≤20 seconds. The RAI failure is declared immediately upon detection of Yellow Alarm or Far End Alarm Channel signals and cleared when those signals are removed.
DS3 interface unavailability is declared at the onset of 10 contiguous PSESs or a failure condition (whichever is earlier). Once unavailable, the interface returns to available at the onset of 10 contiguous seconds with no PSESs; if a failure is also present with clearing time >10 seconds, availability resumes at whichever occurs later.