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