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Cisco Bug: CSCup10271 - SGSN not responding to INBOUND (UL-UNITDATA) messages from UE/BSC

Last Modified

Dec 24, 2016

Products (1)

  • Cisco ASR 5000 Series

Known Affected Releases

15.0(17)

Description (partial)

Symptom:
SGSN not responding to INBOUND (UL-UNITDATA) messages from UE/BSC

Conditions:
Subscribers have active PDP, but is not exchanging data even after moving to another Cell ID (Intra-BSC).  A restart of the Cell-id or clearing the subscriber on the SGSN fixes the issue.. The issue started after moving BSC to Cisco SGSN/MME..  We've seen on the traces that issue seems to intermittent..  We've seen a device to work, and also experience the issue after couple of attempts.
 
Full UE trace can be seen on file TEMS_phone.zip.. From the trace we can observe the following:
 
1.	Last OUTBOUND message coming from SGSN was at 14:06:10:510.  
 
<<<<OUTBOUND  14:06:10:510 Eventid:115054(13)
 
===>BSSGP Message (15 Bytes)
  nsei-7832  bvci-0
 
Message: FLUSH-LL
   TLLI
     Length: 4
     TLLI Value: 0xfb643449 (Local TLLI)
 
2.	Starting from 14:06:10:511 up to 14:57:47:711, there was never an OUTBOUND message coming from SGSN.  During this time, all traffic was initiated by BSC (UL-UNITDATA) but never got a response from SGSN (DL-UNITDATA)..
 
INBOUND>>>>>  14:06:10:511 Eventid:115053(13)
 
===>BSSGP Message (15 Bytes)
  nsei-7832  bvci-0
 
Message: FLUSH-LL-ACK
   TLLI
     Length: 4
     TLLI Value: 0xfb643449 (Local TLLI)
 
Also, during this time, UE was moving from one cell-ID to another (intra-BSC).  We see FLUSH-LL-ACK coming from BSC, but never saw a FLUSH-LL from SGSN:
 
INBOUND>>>>>  13:57:10:925 Eventid:115053(13)
 
===>BSSGP Message (27 Bytes)
  nsei-7832  bvci-309
 
INBOUND>>>>>  14:06:10:510 Eventid:115053(13)
 
===>BSSGP Message (194 Bytes)
  nsei-7832  bvci-316
 
INBOUND>>>>>  14:28:31:377 Eventid:115053(13)
 
===>BSSGP Message (94 Bytes)
  nsei-7832  bvci-313
 
INBOUND>>>>>  14:28:31:379 Eventid:115053(13)
 
===>BSSGP Message (15 Bytes)
  nsei-7832  bvci-0
 
Message: FLUSH-LL-ACK
   TLLI
     Length: 4
     TLLI Value: 0xfb643449 (Local TLLI)
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