Definitions of Managed Object for the DS3/E3 Interface Type
obsoleted by
- rfc-3896 — Definitions of Managed Objects for the DS3/E3 Interface Type
obsoletes
- rfc-1407 — Definitions of Managed Objects for the DS3/E3 Interface Type
Extracted elements (27)
Performance statistics use Gauge32 (PerfCurrentCount/PerfIntervalCount/PerfTotalCount) rather than Counter32 because these values can decrease. Specifically, UAS counts can retroactively adjust when unavailable-second boundaries cross a 15-minute interval window.
The MIB was intentionally aligned with the set of objects that can generally be read from DS3/E3 devices currently deployed, rather than including all theoretically possible management objects for multiplexors, CSUs, and DSUs.
To achieve strict ANSI T1.231 compliance, one-second statistics must pass through a 10-second delay line before updating counters. The agent reads CV counters and alarm flags each second, accumulates into a delay line, and updates interval statistics using data shifted out of the delay line from the previous cycle.
Two separate objects model loopback state: dsx3LoopbackConfig reflects desired state (set by manager) while dsx3LoopbackStatus reflects actual state (including far-end-initiated loopbacks). This distinction is needed because the far end can independently request loopbacks via FDL or inband signaling.
DS3 interfaces use ifType ds3(30), ifSpeed 44736000 (DS3) or 34368000 (E3), and ifHighSpeed 45 or 34 Mbps. ifPhysAddress should carry the Circuit Identifier string, or a zero-length octet string if none assigned.
If the definition of DS3/E3 error conditions in this document does not match the ANSI T1.231 standard, the implementer should follow the definitions described in this document rather than ANSI T1.231.
Setting dsx3Channelization to enabledDs1 causes the agent to create 28 ifEntries of type DS1 in channel order; setting it to disabled destroys them. The dsx1ChanMappingTable entries in the DS1 MIB map DS3 ifIndex and channel number to DS1 ifIndex.
When an agent proxies for DS3/E3 devices and has communication gaps, some performance intervals may be unavailable. dsx3ValidIntervals reports the maximum interval number for which data is available; dsx3InvalidIntervals counts intervals within that range with no data. Missing far-end interval rows return noSuchInstance.
A linkDown trap shall be sent only after the agent has determined for certain that the unavailable state has been entered, but the timestamp on the trap will be that of the first UAS (i.e., 10 seconds earlier). A linkUp trap shall be handled similarly.
dsx3LineIndex should be made equal to ifIndex to allow proper use of ifStackTable. The deprecated prior usage assigned unique identifiers above ifNumber with even/odd numbering for equipment/network sides.
The DS3 interface is unavailable from the onset of 10 contiguous PSESs (P-bit Severely Errored Seconds). While unavailable, only the UAS counter is incremented; all other counters are frozen. The interface becomes available at the onset of 10 contiguous seconds with no PSESs.
The dsx3NoAlarm bit MUST be set if and only if no other flag is set in the dsx3LineStatus bitmap.
The far end cannot undo loopbacks set by a manager; a manager can undo loopbacks set by the far end. Both a LineLoopback and InwardLoopback can coexist; when a NoLoopback is received from the far end while an InwardLoopback was set by the manager, the InwardLoopback remains.
Up to 96 fifteen-minute performance intervals (24 hours) are retained by an agent. Fewer than 96 will be available if the agent was restarted within the last 24 hours, in which case dsx3ValidIntervals reflects the number of complete intervals available.
dsx3Channelization (read-write) indicates whether the DS3/E3 is unchannelized (disabled), channelized into DS1s (enabledDs1), or channelized into DS2s (enabledDs2). Setting this object causes creation or deletion of DS1/DS2 entries in the ifTable.
dsx3IntervalValidData (TruthValue) in both the Near End interval table and Far End interval table indicates whether data for a given 15-minute interval is valid; invalid intervals count as 0 in total table aggregation.
dsx3LineCoding indicates the zero-code suppression scheme: dsx3B3ZS for DS3 or e3HDB3 for E3. These use patterns of normal bits and bipolar violations to replace sequences of zero bits of specified length.
dsx3LineType enumerates DS3/E3 framing variants: dsx3M23 (ANSI T1.107-1988), dsx3SYNTRAN (ANSI T1.107-1988), dsx3CbitParity (ANSI T1.107a-1990), dsx3ClearChannel (ANSI T1.102-1987), e3Framed (CCITT G.751), and e3Plcp (ETSI T/NA(91)18). The type determines interpretation of error and usage statistics.
dsx3LoopbackConfig (read-write) represents the desired loopback state; dsx3LoopbackStatus (read-only) reflects the actual current state including loopbacks established by a manager or requested remotely from the far end. Values include NoLoop, PayloadLoop, LineLoop, OtherLoop, InwardLoop, and DualLoop.
The DS3 Far End Group (ds3 9–12) provides four tables—FarEndConfig, FarEndCurrent, FarEndInterval, FarEndTotal—containing configuration codes (EquipCode, LocationIDCode, FrameIDCode, UnitCode, FacilityIDCode) and far-end C-bit statistics (CESs, CSESs, CCVs, UASs) reported via C-bits from the remote end.
The DS3-MIB module is assigned OID { transmission 30 }, corresponding to ifType ds3(30). It defines managed objects for DS3 and E3 interfaces organized into Near End, Far End, and Fractional groups.
The dsx3ConfigTable (ds3 5) contains per-interface configuration including dsx3LineType, dsx3LineCoding, dsx3SendCode, dsx3LoopbackConfig, dsx3LineStatus, dsx3TransmitClockSource, dsx3LineLength, dsx3Channelization, and dsx3Ds1ForRemoteLoop. It is indexed by dsx3LineIndex.
The Near End performance group consists of three tables: dsx3CurrentTable (current 15-minute interval), dsx3IntervalTable (up to 96 previous 15-minute intervals), and dsx3TotalTable (rolling 24-hour cumulative). All use PerfCurrentCount, PerfIntervalCount, or PerfTotalCount (all Gauge32) for counters including PESs, PSESs, SEFSs, UASs, LCVs, PCVs, LESs, CCVs, CESs, and CSESs.
This document defines the DS3-MIB module with OID { transmission 30 }, registered under the SNMPv2-SMI transmission subtree. The module obsoletes RFC 1407 and is maintained by the IETF Trunk MIB Working Group.
Several read-write objects in this MIB (dsx3LoopbackConfig, dsx3SendCode, dsx3LineType, dsx3LineCoding, dsx3TransmitClockSource, dsx3Channelization) can disrupt normal DS3/E3 interface operation if written by unauthorized parties. SNMPv3 view-based access control (RFC 2275) should be used to restrict write access to these objects.
dsx3LineStatus is an INTEGER (1..4095) bitmap combining multiple concurrent failure and loopback states. Bit positions: 1=NoAlarm, 2=RcvRAIFailure, 4=XmitRAIAlarm, 8=RcvAIS, 16=XmitAIS, 32=LOF, 64=LOS, 128=LoopbackState, 256=RcvTestCode, 512=OtherFailure, 1024=UnavailSigState, 2048=NetEquipOOS.
dsx3LoopbackStatus is an INTEGER (1..127) bitmap representing currently active loopbacks and their sources. Bit positions: 1=NoLoopback, 2=NearEndPayloadLoopback, 4=NearEndLineLoopback, 8=NearEndOtherLoopback, 16=NearEndInwardLoopback, 32=FarEndPayloadLoopback, 64=FarEndLineLoopback.