3.7.1 Understanding the Proprietary DS-1 MIB Module

The proprietary DS-1 MIB module provides management stations with an interface to review DS-1 trunk lines, monitor their status, and report fault conditions using an SNMP trap. It also provides a 24-hour historical fault metrics log in the current, interval, and total tables.

The DS-1 MIB module contains the following tables:

• DS-1 Trunk Configuration Table (dlgDsx1ConfigTable)
• DS-1 Alarm Table (dlgDsx1AlarmTable)
• Metrics Statistics Tables
  • Current Metrics Interval Table (dlgDsx1CurrentTable)
  • Historic Metrics Interval Table (dlgDsx1IntervalTable)
  • Total Metrics Interval Table

3.7.1.1 DS-1 Trunk Configuration Table (dlgDsx1ConfigTable)

The trunk configuration table is identified in the MIB as dlgDsx1ConfigTable. It contains one row entry for each DS-1 trunk line configured for all operational Intel Dialogic and Intel NetStructure boards in the managed node. When a board is in a stopped state or if a board is unconfigured, its trunk lines will not appear in this table. A trunk line can be verified for correct configuration by requesting its row from this table. A trunk line can be monitored for fault information by polling columns from this table.

Line Index Column (dlgDsx1LineIndex)

This column contains the indices for the table. In general, each line is assigned a unique index with the first line starting from '1' and each successive line being assigned indices in ascending order. It is possible for indices to skip, or to not start at one, such as the case when boards are swapped in and out in CompactPCI-based platforms.

Board Index Column (dlgDsx1HiIdentIndex)

For each trunk line, this column contains the index of the board on which the trunk jack is located (near-side). This index corresponds to the indices in the dlgHiIdentTable (Board Identification Table).

Current Interval Elapsed Time Column (dlgDsx1TimeElapsed)

This column contains the time, in seconds, since the start of the current 15-minute metric interval. When this counter reaches 900, the metrics interval has ended, and it is archived in the Historic Interval table (refer to the section describing the Historic Metrics Interval Table (dlgDsx1IntervalTable)).

Valid Metric Intervals Column (dlgDsx1ValidIntervals)

For each trunk line, this column contains the number of elapsed 15-minute intervals since metrics tracking began. It contains a value between 0 and 96.

Line Type Column (dlgDsx1LineType)

This column contains a value that indicates the type of line the trunk is configured to be. The possible values are:

• D4: A T-1 bit rate introduced by AT&T
• E1-CRC: bit rate associated with E-1 lines

Line Coding Column (dlgDsx1LineCoding¹)

This column contains a value for each line that indicates the type of coding in use. The possible values are:

• JBZS
• B8ZS
• HDLC
• TRANS

Loopback Configuration Column (dlgDsx1LoopbackConfig²)

Entries in this column indicate the loopback configuration for each line. The possible values are:

• Normal loopback
• Payload loopback
• Line loopback
• Local loopback

¹ Do not try to set a different LineCoding. Dsx1LineCoding is not able to set values.
² Do not try to set a different LoopbackConfig. Dsx1LoopbackConfig is not able to set values.

Line Status Column

This column can be used to determine the link state of each line in detail. The value contained in each entry is a bitmap that represents the possible conditions that indicate line faults. The bit numbering assumes bit 1 is the least-significant bit (LSB). The bitmap positions have the following meaning:

Bit	Description
1	The line is not indicating any faults
2	The far end is indicating loss-of-frame
3	The near end is sending an alarm indication signal (AIS)
4	The near end is indicating loss-of-frame
5	The near end is indicating loss-of-signal
6	The near end is configured for loopback
7	Time slot 16 of an E-1 line is showing an alarm indication signal
8	Far end is sending an E-1 time slot 16 loss-of-multiframe
9	Near end is sending an E-1 time slot 16 loss-of-multiframe
10	Unclassified failure (other)

Line Signal Mode Column

This column contains the signal mode for each line. The possible values for signal mode are:

• None
• Robbed bit (T-1)
• Bit-Oriented (E-1)
• ISDN

3.7.1.2 DS-1 Alarm Table (dlgDsx1AlarmTable)

The DS-1 Alarm table contains an entry for each trunk on every configured and started Intel Dialogic and Intel NetStructure board on a managed node. The Alarm Type column in this table can be polled to determine high-level alarm flag information for DS-1 trunk lines.

Alarm Table Index Column (dlgDsx1AlarmIndex)

This column is the table index. It corresponds directly to each index that exists in the DS-1 Trunk Configuration Table (see Section 3.7.1.1, "DS-1 Trunk Configuration Table (dlgDsx1ConfigTable)"). For example, if trunk line A is located at index 3 in the configuration table, then it is also represented in the alarm table as index 3.

Alarm Type Column (dlgDsx1AlarmType)

This column contains the current alarm flag for each trunk line. The possible flags values are red, yellow, blue, E-1, and no-alarm. Under normal circumstances, a configured and operational line will indicate the "no-alarm" type. When the alarm type changes to any of the other values, the management station should take the steps necessary to alert the network administrator of a possible trunk fault.

Note: The dlgDsx1TransmitClockSource OID reports a 0 value when a query is issued. The description states that the only values that should be reported are 1,2,3. The dlgDsx1TransmitClockSource OID is not able to use the settable values of 1,2,3.

3.7.1.3 Metrics Statistics Tables

During the analysis of a recurring fault, the user may wish to consult current and historic fault metrics. These metrics may provide some insight into the cause of a faulty trunk. The metrics statistics tables present this information to the user.

Each metric measures an instance of a particular kind of fault. The metrics tracked are:

• Errored seconds
• Severely errored seconds
• Severely errored framing seconds
• Unavailable seconds
• Controlled slip seconds
• Path code violations
• Line error seconds
• Bursty error seconds
• Degraded minutes
• Line code violations

Each fault for each metric is counted for a fifteen-minute interval. The most current, incomplete interval is stored for each trunk line in the Current Metrics Interval table. After a fifteen-minute interval has expired, the metrics counters in the current table are archived in the Historic Metrics Interval table. A third table, called the Total Metrics Interval table, contains the summation of the metrics counters in all the archived intervals, for each line, in the Total Metrics interval table.

Current Metrics Interval Table (dlgDsx1CurrentTable)

This table contains one index column called dlgDsx1CurrentIndex. Indices in this column correspond one-to-one with the indexed entries of the DS-1 Trunk Configuration table (see Section 3.7.1.1, "DS-1 Trunk Configuration Table (dlgDsx1ConfigTable)").

Historic Metrics Interval Table (dlgDsx1IntervalTable)

The historic metrics interval table contains archived 15-minute intervals for up to the last 24 hours of service. There are 96 15-minute intervals in 24 hours, so this table may contain up to 96 entries for each trunk line.

This table has two index columns. The first index corresponds one-to-one with the indexed entries of the DS-1 Trunk Configuration table. The second index identifies the interval number. The interval number ranges from 1 to 96, with 1 as the most recent interval and 96 as the least recent interval.

Total Metrics Interval Table

The Total Metrics Interval table contains the sum of all interval metrics for each trunk up to the last 24 hours. It has one index column called dlgDsx1TotalIndex. Each index in this column corresponds one-to-one with the indexed entries of the DS-1 Trunk Configuration table.

3.7.1.4 Trunk Line Status Trap

This trap is sent whenever an entry in the Line Status column changes value. The trap contains the index into the configuration table of the line affected and the line status bitmap value.

3.7.1.5 A Typical DS-1 Configuration

The following is an example of a typical DS-1 Trunk Configuration table:

dlgDsx1- LineIndex	dlgDsx1- LineType	...	dlgDsx1- LineStatus	dlgDsx1- SignalMode
1	dlgDsx1D4	...	1	dlgDsx1Isdn
2	dlgDsx1D4	...	1	dlgDsx1Isdn
3	dlgDsx1D4	...	96	dlgDsx1Isdn
4	dlgDsx1D4	...	96	dlgDsx1Isdn
5	dlgDsx1E1CRC	...	1	dlgDsx1BitOriented
6	dlgDsx1E1CRC	...	1	dlgDsx1BitOriented
...	...	...	...	...

The following is an example of a corresponding DS-1 Alarm Table:

dlgDsx1AlarmIndex	dlgDsx1AlarmType
1	No Alarm
2	No Alarm
3	Red Alarm
4	Red Alarm
5	No Alarm
6	No Alarm
...	...

These two tables contain 6 trunk lines: 4 configured as T-1 lines and 2 as E-1 lines. Two of the T-1 lines show a line status of 96, which is a bitmap that indicates near-end loss-of-frame and loss-of-signal faults. The indices for these two lines are 3 and 4. It is clear in the DS-1 Alarm table provided that the trunks represented by rows 3 and 4 are showing a red state, consistent with the fault indications in the configuration table. To further diagnose the problem, you can try analyzing the metrics counters in the current interval table to determine if the faults may be frame-related, bit-level, etc. The actual analyzing of each metric type to diagnose a difficult-to-diagnose line fault is beyond the scope of this document.

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