Routing area Update

Hello Hellsing,

“Gn” interface, between SGSN and GGSN ? I cannot find any valid reason why it would behave in such a way. It is not normal, and should not even be possible ! 🙂

Have you done any other change ? For example, activation of the Gs interface, or actvation of LA/RA combined update ? Change of LAC planning, or RAC planning, on the radio side ?

Cheers,
pix

hellsing,

yes, if there is only one SGSN instead of 2, then you should see less inter-SGSN RA updates. But the number of RAU (inter+intra) should be the same as before.

The RAU is a procedure starter by the MS. The MS doesn’t care about your Gn interface… it just cares about the RA in the new cell : same or different than before ?
If different, then a RAU is done.

I’m not familiar with interSGSN RAU : are they going through the GGSN ? I thought the SGSN would contact the other SGSN directly… (to be verified !)

periodic RA : after expiry of a timer, the MS is forced to perform a RA update, even if it didn’t move

normal RA : the MS has moved and changed RA, physically.

Periodic RA increase is due to timer change only.

Check out 23.060
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6.2.2.
The Periodic RA Update Timer function monitors the periodic RA update procedure in the MS. The length of the periodic RA update timer is sent in the Routeing Area Update Accept or Attach Accept message. The periodic RA update timer is unique within an RA. Upon expiry of the periodic RA update timer, the MS shall start a periodic routeing area update procedure.
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and also 24.008
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4.7.5.1
Periodic routing area updating is used to periodically notify the availability of the MS to the network. The value of the update type IE in the ROUTING AREA UPDATE REQUEST message shall indicate “periodic updating”. The procedure is controlled in the MS by timer T3312. When timer T3312 expires, the periodic routing area updating procedure is started. Start and reset of timer T3312 is described in subclause 4.7.2.2.
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So the timer is called T3312 ! Default value is 54mn.
The value of this timer is used if the network does not indicate another value in a GMM signalling procedure. For example in the Routing Area Update Accept : the SGSN can indicate a different timer.

Cheers,
Pix

In the same context, i take a Gn (Inter SGSN) Trace with wireshark to investigate about Inter SGSN RAU failure, how can i find Inter SGSN RAU message among my trace?

Thanks pix , i’m on it now.

Hi,

You must have same RAC in unique PAPU..Otherwise it will cause failure & 2955 will be triggered..

Ultimately,RAC planning should be done in such as way that same RAC remain unique between PAPU…you should use same RAC in bsc such a way that you can manage these BSC in same PAPU..Thats all..!