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Bug #2956

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

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

Status:
New
Priority:
Low
Assignee:
-
Category:
-
Target version:
-
Start date:
02/17/2018
Due date:
% Done:

0%

Estimated time:
Spec Reference:

Description

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

History

#1 Updated by laforge 5 months 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

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