Sunday, 4 October 2015

FDD-eNodeB-A case of "eNB is working normally but No throughtput",which caused by limitation of license for MME.

 Incident Description (Incident Phenomena)
1. An eNB in some fdd project, after the commissioning , no alarm committed by the eNB, and the RRU power was diagnosised as normal. The UE can access successfully but no throughput . Reading the signaling tracing result , we found that the initialization UE request message has been sent to MME, but no acknowledgement.
2. confirm that the SCTP/S1AP status is normal, and no any message arrived to Initialization UE Request.
3. By scratching the S1-link packages , we found that S1AP messages has been sent to the MME gateway, but MME engineer confirmed again that no message of Initialization UE Request.
4. At the same time , some other sites were commissioned . The problem appearredon each of them .
 Networking Environment
 Problem Cause Analysis
Accordng to the appearance, we doubted that it might because of the limitation from MME.
   After so much noneffective trial, we could only select an unconventional method to the location problem. That was to make some changement into the current normal sites, to change the remote IP address of SCTP, and incrementally synchronize the data into the sites. To confirm that whether the faulted sites could came into good ones .
Result of operation:
   By the changement and synchronizatin, the faulted sites service began to be provided well. Then we could ask the MME engineer to take the troublshooting deeply.
Final reason:
   At last, the MME engineer confirm that the license 4G function is not activated. Our customer ever apply for a new license for 4G before, but after the new license is imported, the local operator engineer didn't reset the SMP board. This misoperation will bring the problem as SCTP/S1AP is seemed ok, but service could not provided for UE as normal .

Budi Prasetyo

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