SGSN detach flag

Dear, kamal kotecha! When network works in NMO1 (Gs-interface between MSC/VLR and SGSN) and MS is in both GPRS-attached and Imsi attached states then Implicit Detach Timer in MSC/VLR must be blocked by MSC/VLR and it must relys on Mobile Reachable Timer in the SGSN (MRT) 3,5???. Also there is no Periodic LA update in this situation – but only Periodic RA Update (PRU). You need to set the correct values for MRT and PRU timer (T3312) in SGSN!!! – not in BSS. See also 23.060 for overall description of combined procedures.

Thanks, Pix! But we must wait the response from Kamal. This problem may be deeper than we are thinking 🙂

Hi, Kamal!

READY STATE TIMER – the time during which the MS is staying in Ready state (performing cell updating) after the packet data transfer is completed.
STANDBY STATE TIMER – is non-standart timer, see your documentation. May be it is the timer of the forced detach from SGSN to MS.
MS REACHABLE TIMER – analog of the VLR Implicit Detach Timer in SGSN.
DETACH TIMER – in SGSN or in VLR? See documentation. Probably Implicit Detach Timer in VLR.
PERIODIC RA UPDATE TIMER – analog of GSM Periodic LA Update timer in GPRS.
VLR PERIODIC CLEANING START TIME – see documentation. Probably – the start time of the VLR periodic cleaning (may be purging) after meeting some conditions (like STT, UDC below).
DETACHED SUBSCRIBER STORAGE TIME – see documentation. Probably – the time after which the detached subscriber can be deleted from VLR after meeting condition below (UDC).
UTILISATION RATE DEPENDENT CLEANING – see documentation. Probably, condition which cause VLR periodic cleaning above.
UTILISATION RATE ZERO LIMIT – see documentation.
FORCE TO STANDBY – the feature in SGSN, allowing the SGSN to reset the Ready Timer in MS and force it go to Standby (Yes/No).
OVERRIDE MS READY STATE TIMER – see documentation. Probably, deactivation Ready timer in MS (Yes/No).

Kamal! Could you answer the questions:
DETACH TIMER – in SGSN or in VLR? If SGSN then what is it’s meaning?
DETACHED SUBSCRIBER STORAGE TIME – in VLR or SGSN?
UTILISATION RATE DEPENDENT CLEANING – in VLR or SGSN?

Kamal!
1)You said “I have mentioned all below para of SGSN only…” But VLR PERIODIC CLEANING START TIME parametr concerns VLR only, isn’t it?
2)Is Detach Timer resets, if MS performs Periodic RA Updatig only when Detach Timer is running?
3)Can you do a tests with suspect Ericsson mobile – switch on, GPRS attach+IMSI attach and wait while IMSI detach will occurs (without establishment GPRS sessions and voice call). Is it occured in VLR only, SGSN only or both SGSN and VLR? Exact time expired after switch on?

hi, Kamal!
I am thinking that most Nokia mobiles (when switching on) not perform Combined Attach and stay in GMM Idle (GPRS Detached) state on default. But I don’t know about others.
On your place, I would try to do as follows:
1)take the suspect mobile and switch it on;
2)then check out the subscriber status in SGSN (GPRS Attach/detach?) and VLR (Imsi attach/detach?).
3)If both flags are attached then wait without making any voice or data activities..It is very desirably to observe the signalling exchange concerning that subscriber on Gb- (e.g. Periodic RA Update, Detach message from SGSN etc.) and Gs-(e.g. Imsi Detach Indication etc.) interfaces.
4) If for example you will find out that after Detach timer expiry (3,5 h) in SGSN IMSI is detached also in VLR then more likely than not that your SGSN have abnormal behavior.
p.s. I am not working with Nokia equipment (with the exclusion of my Nokia handset:)
B.R.

Dear all,
In the frame of this discussion, could you please suppprt/help me on how to find the : IMSI Implicit Detach Timer for Nokia MSS/
The MML command to extract the same please.

Thanks a lt in advance.

Mohamed