Fwd: Losing ACKs due TLLI changes?

Holger Hans Peter Freyther hfreyther at sysmocom.de
Wed Oct 30 17:18:00 UTC 2013

On Wed, Oct 30, 2013 at 06:26:57PM +0200, Vladimir Rolbin wrote:

> I don't see any print connected to the Uplink TBF request for "Attach
> accept" (by MS). At this moment the TLLI has been already updated but UL
> TBF still does not exist

I don't understand that part? What happens here is that we poll for
a PACKET CONTROL ACK. So we know the TBF based on the FN. And in this
TBF we notice that the TLLI has changed (ACK is using the new TLLI
that is derived from the P-TMSI).

> (what bts->tbf_by_tlli(m_tlli, GPRS_RLCMAC_UL_TBF) returns?). Corresponding
> to TS 04.60, 11.2.29 Packet Uplink Assignment possibly may use DL TFI to
> address the MS in place of TLLI (we still don't know if it's accepted or
> not by MS). Also the uplink FN may be used to find corresponding UL TBF
> context (according to Packet Uplink Assignment RRBP field) for UL Packet
> Control Ack which contains relevant TLLI.  So is it really necessary to
> link UL and DL TBFs in the case? ...

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