DL Throughput to zero after handover inter-vendor

Hi Experts.
Anyone here have experience with inter-vendor HO in LTE?
I’m facing DL Throughput to zero after handover and I see that in PDCP PDU: bearer id after handover instead 3 has al time 0 value
But rrcConnReconfig msg is fine.

During ho security key / algo changed so if UE and eNB has different security key.
So all packet will drop and throughput lead to 0.

Reconfig complete sent successfully?

In opposite directions is OK.
And PDCP length is 5 bits.
Must be CP PDCP.

Maybe after reconfiguration complete s1ap path switch request till response there is a issue.
Check gtp related counter.
Is it particular neighbor site or what?

No, it is happening on all sites.
Yes, need to check pcap logs from eNB.

PDCP sequence length same or different in sites?

The same, 5 bits after HO.

PDCP sequence length normally is 7 bits or more than that.
5 bits is less.

Yes, usually is 12 bits but for PDCP CP is 5.

What’s pdcp cp by the way? (I don’t remember)
I think there is gtp issue.
Check s1gtp counter in X2.
Path switch issue I guess.
After reconfiguration failure you can check from KPI too.
Because it goes to zero and this is execution case.
As you said reconfiig complete done

For SRB data, the problem is that I don’t see bearer id for DRB.
On RLC layer only visible rlc_control pdus, no rlc_data.
As you say, need to see the other interfaces, from UE point of view just no DL data transfer.

But in reconfiguration we see DRB bearer.
In normal access can you see DRB message in reconfiguration?

Yes, the bearer is configuring normal but after that becomes inactive.
I mean no any pdcp with that bearer id.

So any drb configuration issues?
What’s pdcp discard time in non gbr?

No, the config msg is correct.


So I guess you have gtp issues.
Transmission issues?
After reconfiguration s1 path reject happening?

Yes, possible.

I doubt.

Not sure about that, I’m waiting for the pcap logs.

Ok, let’s see. You can check from OSS kpi too.

Between which vendor’s?