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Cisco Bug: CSCvv18943 - MME not sending ERABModifyRequest for dedicated bearer when UBR is triggered for default & dedicated

Last Modified

Sep 26, 2020

Products (1)

  • Cisco ASR 5000 Series

Known Affected Releases

21.20.2

Description (partial)

Symptom:
During feature testing we came across a scenario when we will potentially need to do both a Modify Bearer Command (MBC) procedure and a delayed ERAB procedure.
 
Currently the Bearer Request feature was scoped under the assumption we would only need to do either a MBC procedure or a delayed ERAB procedure, but not both.
 
Essentially this scenario occurs when there is extra dedicated Bearer information in the stored UBR.
 
The MBC procedure will only process the Default EPS Bearer, however we still need to inform the UE of the other dedicated bearer details in the stored UBR.
 
Therefore in this scenario we propose to perform a delayed ERAB procedure (after the MBC procedure) so the remaining bearer details from the stored UBR are sent to the UE.

Conditions:
Bearer Request Feature enabled in CLI

During a 3g-to-4g GnGp TAU/Handover procedure a UBR was buffered containing both Default and Dedicated bearer IEs.

On completion of the TAU/HO procedure if a Modify Bearer Command procedure gets triggered only the Default bearer info will be sent to the UE.

Unfortunately the stored dedicated bearer info will not be sent to the UE.
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