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ERAB modification fail due to radio interface procedure in EnodeB Nokia

+2 votes
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does anyone have an idea about sudden increase in ERAB modification fail due to radio interface procedure in EnodeB Nokia FL15A ?
This was launched after spliting TAC_1 in TAC_1 + TAC_2 in order ot reduce the signalling in MME.
But rollback was done and problem still not resolved.

posted Jan 26, 2017 by Jalloul Bouchkara

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1 Answer

0 votes

An eNodeB sends failure when it gets failed to handle ERAB modification procedure with the appropriate cause. Please have a look into the cause value received in ERAB Modify Response for associated ERAB ID. Unsuccessful scenarios have been captured in specification. For example: If E-RAB Modify Request message carries "Invalid" E-RAB ID or "Invalid QoS". Invalid QoS means when E-RAB was establishment then it was non-BGR and now requested to make it a GBR.

answer Jan 28, 2017 by Neelam
Thanks.
I would like to say that the cause from LTE Counter is "Network Layer Cause": DRB is not ACK by the UE after Timer expiration.
EnodeB waits for the answer for the confirmation of the new DRB sent to UE, after Timer expiration, it send Failure to MME.
Some traces shown that after TAC update in LTE, the UE is moved to 3G
That why no response has been got from the UE.
Similar Questions
+1 vote

From MME to eNodeB, UE context modification procedure is triggered I know but what makes trigger of UE Context modification procedure from eNodeB to MME ?

0 votes

When target eNodeB is not able to allocate resource for all the bearers which comes as part of Handover Request message, it sends handover request ack with partial success since "E-RABs Failed to Setup List" is present in HOReqAck message.
What MME or source eNodeB does in that case ? Does any action taken by MME for the E-RABs which failed to setup at target eNodeB or some other actions taken ?

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