UEContextReleaseCommand from MME with cause:nas:normal-release

CORE
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1

Hello Friends.

Getting UEContextReleaseCommand from MME with cause:nas:normal-release, after approx 4 seconds, of handover command to the UE.

What could be the possible scenario you can think of here?

2

Might be expiry of S1RelocOverall timer.

Is handover successful at target cell?

Handover notify was sent by target BTS to MME?

3

Target cell traces not available.

Handover failure case.

For sure.

HO was over x2.

I mean preparation.

4

Then “UEContextReleaseCommand from MME with cause:nas:normal-release” is normal behaviour.

It is result of handover failure and the cause.

Find cause from UE logs.

5

Thanks!

Does it mean UE is lost, what timer play role here for release from MME?

6

Has source eNb send UE context release request to MME?

I guess yes. Please confirm.

This looks like X2RelocOverall case not S1relocOverall case since you mention X2 handover.

7

No Source eNB has not sent any such request.

I think, that UE has done re establishment after HO failure and failed, and then attempted a new session, but since the context was already in source eNB, so the MME clears old context.

8

Where RRE happened?

Source eNB or target?

9

Not at source, no logs on this.

I am trying to guess the scenario.

10

Yes this may be the case then.

But MME cause is normal, actual cause HO failure.