Bug #2956

GMM DETACH REQUEST (power-off) results in LLC XID

Added by laforge over 1 year ago. Updated 11 days ago.

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


Spec Reference:


When sending a GMM DETACH REQUEST (power-off), we send a XID RESET.

As per Figure 4.7.4/1 of 3GPP TS 24.008, the DETACH REQUEST is a unilateral L3 message with no response/follow-up.

Now of course it's questionable how to react in case the TLLI is unknown, and our attempt at recovering from that is to send a XID. That may or may not be the right thing to do here. I'm unsure.

Sat Feb 17 15:02:20 2018 DLLC <0012> gprs_llc.c:526 LLC RX: unknown TLLI 0xcf6b13e6, creating LLME on the fly
Sat Feb 17 15:02:20 2018 DLLC <0012> gprs_llc_parse.c:81 LLC SAPI=1 C   U GEA0 IOV-UI=0x000000 FCS=0x270d39 CMD=UI DATA 
Sat Feb 17 15:02:20 2018 DMM <0002> gprs_gmm.c:1919 Cannot handle GMM for unknown MM CTX
Sat Feb 17 15:02:20 2018 DLLC <0012> gprs_llc.c:1076 LLGM Reset
Sat Feb 17 15:02:20 2018 DMM <0002> gprs_gmm.c:1463 MM(---/ffffffff) -> GMM DETACH REQUEST TLLI=0xcf6b13e6 type=GPRS detach Power-off
20180216-sgsn-detach-xid.pcap 20180216-sgsn-detach-xid.pcap 488 Bytes laforge, 02/17/2018 02:06 PM


#1 Updated by laforge over 1 year ago

  • Subject changed from GMM DETACH REQUEST for unknown TLLI results in GMM DETACH ACCEPT to GMM DETACH REQUEST (power-off) results in LLC XID

#3 Updated by laforge 4 months ago

  • Category set to Gb interface
  • Assignee set to lynxis

#4 Updated by lynxis 3 months ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 90

The problem is already fixed. However I've extended the ttcn3 test case to catch this.
Leaving this ticket open as long the ttcn3 patch is not uploaded and merged into master.

#5 Updated by lynxis 11 days ago

  • Status changed from In Progress to Closed
  • % Done changed from 90 to 100

all poweroff related ttcn3 tests are green.

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