Sudden increase in VoLTE drop after SW upgrade

Hi Ericsson Experts,

There is sudden increase in VoLTE drop (NUM) after software upgrade.

But not pegging in below counters.
Pm DCT
Pm HPR
Pm HO
Pm TNFAIL
Pm UELOST

So what can be a reason? I mean which counter I can check?

Vendor is Ericsson, L20

RNL MME or DRD issue in VoLTE.
What about packet loss in qci1?

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Check first the related counter of eNB initiated or MME initiated.

If MME initiated increase then it’s normal in 20, it’s a software bug problem.
You can talk to Ericsson PDU for more detail, and will be fixed in 21.

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Not in “PM MME” drop as well…

Then it must be eNodeB initiated if not MME initiated.

Don’t predicted @RFSpecialist, let him see first and if possible share both counter performance.
Fetched 2 counter first.

Has anyone changed the tilting of the cell in the 5th of march to be overshooting for example?
Check the timing advance or Out of Coverage in case TA not available.

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-There is SW Upgrade on 5th (to L20).
-We don’t have TA in Ericsson.

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Has anyone changed PCI or RSI configuration?

Then I am afraid the some parameters were set to default values; such issue occurred before in different networks.
Perform parameter audit before and after the SW upgrade.
Especially for hidden parameters.

Yeas, that is valid point & I’ll check.
I was just looking for any other counter which should peg to match exact Drop count in L20.

Why abnormalMME release were empty in Excel?
Also mapped abnormaleNB to look.

Not pegging.

If not pegging than mapped sum of numerator must be equal to counter value abnormaleNB.
Please check it and confirm.

This is what i am looking for.
You can see before upgrade it was equal but not after 5th so there might be some counter in L20 which I am missing.

All qci1 counters = drop (NUM).

First thing there is no any other counter on 20.
Second, in your excel you mark the sub counter.
In Ericsson you can not calculate like sub counter sum equal to parents counter (abnormaleNB)
Should not be like that.
Mapped your Num formula with abnormal eNB parent counter fist in case you sure no pegging of MME release counter.
Must be same.

  1. Check the number of CSFB attempts, does it following the same trend.

  2. Also is this the global impact or in specific sites only.

  3. Check the SRVCC Threshold settings might this be changed to default values.

You should check the pmerababnormalenbpspartfailqci. If the Core is Huawei, the counter is increased by sending unspecific cause instead of normal release in path switch acknowledge.