In ProTrace, Missing Traffic on Some Links Because of "backward MSU"

Asset ID:	1-72-2272687.1
Update Date:	2017-11-12
Keywords:

Solution Type Problem Resolution Sure

Solution 2272687.1 : In ProTrace, Missing Traffic on Some Links Because of "backward MSU"

Applies to:

Oracle Communications Performance Intelligence Center (PIC) Software - Version 10.0.0 and later
Information in this document applies to any platform.

Symptoms

Missing traffic on some specific links in xDR session and correlation rate is impacted.

eagleMonitor log contains:

0519:083740.767 TR-V DbMsuBlock00 DBMsuBlock::add Discared backward MSU since over the recovery range, link 0, id 277120. 05/19/2017 08:37:40.415:150918 delta=15952 msec MaxBackwardTime=4294 lastBackwardMsuLogTime=1495183056 [7288/DBMsuBlock.C:296]
0519:083743.008 TR-V DbMsuBlock00 DBMsuBlock::add Discared backward MSU since over the recovery range, link 0, id 314510. 05/19/2017 08:37:43.005:525918 delta=13842 msec MaxBackwardTime=4294 lastBackwardMsuLogTime=1495183060 [7288/DBMsuBlock.C:296]

"Out of Sequence" alarm can be raised.

Changes

None.

Cause

One or several cards of IMF is having NTP troubles (Module Ntp_utl.c Line 1467 Class 0001 Severity 1).

Check ntp related alarms on eagle cards:

Module Ntp_utl.c Line 1467 Class 0001 Severity 1

These are usually preventing IMF to process trafic properly.

Solution

Eagle side

Refer to 1966585.1

PIC side

Verify ntp configuration on PIC

How to Check if IMF is Providing a NTP Source to Eagle STP (Doc ID 1930839.1)
Oracle Communications Performance Intelligence Center (PIC) How to Configure NTP? (Doc ID 2083591.1)

On PIC 10.x

In previous version of PIC (before PIC 10.x), one link was mapped to one partition of IDB table (DbLinkTblMap).

In PIC 10.x, to improve IMF performances and capacity (255 links per MG limit), it is split differently. There are 4 statics partitions:

Link (STC copy)
Link (FC FastCopy)
Association (FC)
Q752 statistics

Whatever the release, the log "add Discared backward MSU since over the recovery range" and the drop of MSU will happen if MSU are too much out of sequence.

In PIC 9, links carried by the card might face issue. In PIC 10, impact might be links from other cards as well.

"Out of Sequence" alarms

"Out of Sequence" alarms can be a sign that an Eagle card might be drifting. It can also be normal as traffic can be received disorderly (timestamp) because it comes from different cards.

This alarm does not imply any dataloss. Alarm level can be ignored by changing severiy.

References

<NOTE:1966585.1> - Module Ntp_utl.c Line 1467 Class 0001 Severity 1
<NOTE:1900854.1> - xDR Correlation Rates Drop Down Due to NTP Synchronization Issues

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