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"? As I know, there are content resolution on network side and on MS side. The contention resolution at one phase access is successfully completed on the MS side when the mobile station receives a PACKET UPLINK ACK/NACK. The contention resolution at two phase access is completed at MS when it receives the second uplink assignment message with its TLLI included.
Also I can't understand why we should use IMSI in pcu? Why it is not enough to use TLLI?
2013/10/27 Holger Hans Peter Freyther hfreyther@sysmocom.de:
Hi,
I got this log from the pcu while using my E71 (the only sub in this network).
<0007> gprs_rlcmac_meas.cpp:103 UL RSSI of TLLI=0x88661bc6: -67 dBm <0002> bts.cpp:945 Got ACK, but UL TBF is gone TLLI=0xe512eba3 <0007> gprs_rlcmac_meas.cpp:158 DL packet loss of IMSI=274080000004765 / TLLI=0xe512eba3: 0% <0002> tbf.cpp:668 TBF TFI=0 TLLI=0x88661bc6 T3169 timeout during transsmission <0002> tbf.cpp:690 - Assignment was on PACCH <0002> tbf.cpp:694 - No uplink data received yet
So there is an ACK for TLLI=0xe512eba3 but at the same time the tlli 0x88661bc6 is timing out.
PCU->SGSN TLLI=0x88661bc6 Attach Request SGSN->PCU TLLI=0x88661bc6 Attach Accept (new P-TMSI) PCU->SGSN TLLI=0xe512eba3 Attach Complete (new TLLI) (6s later)
Now the question is how the PCU should behave. I think the MS is allowed to change the TLLI (after a P-TMSI assignment) after the contention resolution is completed. From my reading there is no content resolution on the UL. My E71 appears to run into a timeout and then issue a RACH request to send the Attach Complete. I think I have seen other equipment failing to transmit the Attach Complete at all.
I think for the SGSN -> PCU side we should generally look things up by IMSI (there is already a warning in the code), for the MS->PCU side. I think we should store the old and new TLLI (and then put new_tlli into tlli once the new one is being used).
comments? holger
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- Holger Freyther hfreyther@sysmocom.de http://www.sysmocom.de/
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