Bug #2731

OpenBSC doesn't release lchan if MSC does a hard SCCP disconnect

Added by laforge 3 months ago. Updated 5 days ago.

Target version:
Start date:
Due date:
% Done:


Spec Reference:


When the MSC doesn't follow normal procedure of ClearCommand but simply hard disconnects the SCCP connection (such as possible in any number of failure scenarios), we are not clearing the lchan / radio channel:

<000a> osmo_bsc_sigtran.c:258 Initializing resources for new SIGTRAN connection to MSC: RI=SSN_PC,PC=0.23.1,SSN=BSSAP,GTI=NO_GT...
<000a> osmo_bsc_sigtran.c:287 Allocated new connection id: 27
<000a> osmo_bsc_sigtran.c:315 Opening new SIGTRAN connection (id=27) to MSC: RI=SSN_PC,PC=0.23.1,SSN=BSSAP,GTI=NO_GT
<001a> osmo_bsc_sigtran.c:196 N-CONNECT.cnf(27)
<001a> osmo_bsc_sigtran.c:220 N-DISCONNECT.ind(27, cause=768)
<000a> osmo_bsc_sigtran.c:381 sccp connection (id=27) not cleared (gsm subscriber connection still active) -- forcefully clearing it now!
<0005> bsc_api.c:291 The lchan should have been cleared.

OsmoBSC> show lchan 
BTS 0, TRX 0, Timeslot 1, Lchan 0: Type TCH_F
  Connection: 0, State: ACTIVE
  BS Power: 3 dBm, MS Power: 16 dBm
  Channel Mode / Codec: signalling
  No Subscriber
  Bound IP: Port 0 RTP_TYPE2=0 CONN_ID=0
  Measurement Report:
    Flags: DLinval 
    RXL-FULL-ul: -110 dBm, RXL-SUB-ul: -110 dBm RXQ-FULL-ul: 0, RXQ-SUB-ul: 0

I'm adding testcase TC_chan_rel_hard_rlsd about this to the BSC_Tests TTCN-3 testuite.

Related issues

Related to OsmoBSC - Bug #2726: OsmoBSC doesn't release lchan if MSC refuses connection (CR -> CREF) Resolved 12/08/2017


#1 Updated by laforge 3 months ago

  • Related to Bug #2726: OsmoBSC doesn't release lchan if MSC refuses connection (CR -> CREF) added

#2 Updated by laforge 3 months ago

  • Assignee set to dexter

#3 Updated by laforge about 2 months ago

  • Status changed from New to In Progress
  • Assignee changed from dexter to laforge
  • % Done changed from 0 to 70

I have a patch for this in Change-Id I64a46b5bcd4272e3fa2ff4ee824c2f3fdff6854b of the lafogre/fsm branch

#4 Updated by laforge about 2 months ago

  • Priority changed from Normal to High

#5 Updated by laforge about 1 month ago

  • Status changed from In Progress to Stalled

waiting for dexter to complete the work on the FSM branch

#6 Updated by laforge 5 days ago

  • Status changed from Stalled to Resolved
  • % Done changed from 70 to 100

fsm branch has been merged (including related patch). BSC_Tests.TC_chan_rel_hard_rlsd now passes.

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