Losing ACKs due TLLI changes?

Holger Hans Peter Freyther hfreyther at sysmocom.de
Mon Oct 28 15:23:24 UTC 2013

On Mon, Oct 28, 2013 at 06:17:50PM +0400, Ivan Kluchnikov wrote:
> Hi Holger,


> Can you send full pcu tbf debug log for this attach procedure?
> I want to understand, in which place of TBF MS starts use new TLLI.
> What do you mean by "no content resolution on the UL"?

s/content resolution/contention resolution/. Sorry.

I don't have a log file but with the routing area update, the
SGSN may assign a new P-TMSI and if a new P-TMSI was assigned
with the "Accept" message, a "Complete" message needs to be
generated by the MS. This message can/should already contain
the new TLLI (which is derived from the P-TMSI).

> Also I can't understand why we should use IMSI in pcu?
> Why it is not enough to use TLLI?

The TLLI is either random (I have not seen this), foreign
or local. In the last two cases it is derived from the P-TMSI.
The P-TMSI can change (e.g. at routing area update).

- Holger Freyther <hfreyther at sysmocom.de>       http://www.sysmocom.de/
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