4 May
2012
4 May
'12
8:25 a.m.
Hello,
I use OpenBSC/GPRS (sw version only few weeks old) with nanoBTS and this works well mith
many mobile devices.
With Nokia devices, however, I do not get a PDP context. Here is an osmo-sgsn trace of
Nokia E65:
<0012> gprs_bssgp.c:347 BSSGP TLLI=0x795b37eb Rx UPLINK-UNITDATA
<0013> gprs_llc.c:478 LLC SAPI=1 C FCS=0xc2ab0aCMD=UI DATA
<0013> gprs_llc.c:742 LLC RX: unknown TLLI 0x795b37eb, creating LLME on the fly
<0002> gprs_gmm.c:636 -> GMM ATTACH REQUEST MI(001011474110317) type="GPRS
attach"
<0002> gprs_gmm.c:351 <- GPRS ATTACH ACCEPT (new P-TMSI=0x78bb36bb)
<0012> gprs_bssgp.c:523 BSSGP BVCI=2 Rx Flow Control MS
<0012> gprs_bssgp.c:523 BSSGP BVCI=2 Rx Flow Control MS
<0012> gprs_bssgp.c:347 BSSGP TLLI=0xf8bb36bb Rx UPLINK-UNITDATA
<0013> gprs_llc.c:478 LLC SAPI=1 C FCS=0xc2ab0aCMD=UI DATA //remark: is a
repetition of GMM ATTACH REQUEST
<0013> gprs_llc.c:525 TLLI=f8bb36bb dropping UI, N(U=0) not in window V(URV(UR:1).
<0012> gprs_bssgp.c:347 BSSGP TLLI=0xf8bb36bb Rx UPLINK-UNITDATA
<0013> gprs_llc.c:478 LLC SAPI=1 C FCS=0x478a8dCMD=UI DATA
<0002> gprs_gmm.c:1047 -> ATTACH COMPLETE
<0012> gprs_bssgp.c:523 BSSGP BVCI=2 Rx Flow Control MS
<0012> gprs_bssgp.c:523 BSSGP BVCI=2 Rx Flow Control MS
<0012> gprs_bssgp.c:347 BSSGP TLLI=0xf8bb36bb Rx UPLINK-UNITDATA
<0013> gprs_llc.c:478 LLC SAPI=1 C FCS=0x478a8dCMD=UI DATA //remark: is a
repetition of ATTACH COMPLETE
<0013> gprs_llc.c:525 TLLI=f8bb36bb dropping UI, N(U=1) not in window V(URV(UR:2).
<0012> gprs_bssgp.c:347 BSSGP TLLI=0xf8bb36bb Rx UPLINK-UNITDATA
<0013> gprs_llc.c:478 LLC SAPI=1 C FCS=0x29e399CMD=UI DATA
<0002> gprs_gmm.c:782 -> GMM DETACH REQUEST TLLI=0xf8bb36bb type=GPRS detach
<0002> gprs_gmm.c:425 <- GPRS DETACH ACCEPT
<0012> gprs_bssgp.c:523 BSSGP BVCI=2 Rx Flow Control MS
<0012> gprs_bssgp.c:523 BSSGP BVCI=2 Rx Flow Control MS
<0012> gprs_bssgp.c:523 BSSGP BVCI=2 Rx Flow Control MS
We see some dropped frames here which are in fact retransmissions sent by the Nokia
device. After the successful GPRS Attach, the Nokia device refuses to send an ACTIVATE PDP
Context REQ. Most Nokia devices get asked for IMSI and IMEI during the GPRS ATTACH, which
her does not happen. However, these retransmissions are characteristical for all Nokia
devices I've tested so far (6021, C5, C7, E65, 3109c).
Is there a timing problem between osmo-sgsn and Nokia devices? Can I tune osmo-sgsn's
parameters to make the connection work?
Any help would be appreciated.
cheers
Olaf
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4 May
4 May
1:39 p.m.
hi Olaf,
On Fri, May 04, 2012 at 02:25:28PM +0200, Olaf Schulz wrote:
I use OpenBSC/GPRS (sw version only few weeks old)
with nanoBTS and
this works well mith many mobile devices. With Nokia devices,
however, I do not get a PDP context. Here is an osmo-sgsn trace of
Nokia E65:
This is very likely a problem related to TLLI state tracking and LLC
sequence numbers. We have seen this for probably something like one
year in OsmoSGSN and sadly nobody has had enough of a problem with it to
actually debug it completely, fix it and contribute back a fix :/
Our own development is very much oriented towards features and fixes
that are required/requested by our own customers, and none of them is
using OsmoSGSN outside of a lab context, i.e. where those bugs would
cause a major inconvenience.
I guess it would require something like one day of focussed work to get
those TLLI and LLC sequence number issues sorted out.
Regards,
Harald
--
- Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
(ETSI EN 300 175-7 Ch. A6)
6 May
6 May
6:18 a.m.
On Fri, May 4, 2012 at 7:39 PM, Harald Welte <laforge(a)gnumonks.org> wrote:
hi Olaf,
On Fri, May 04, 2012 at 02:25:28PM +0200, Olaf Schulz wrote:
Please see my posts from a few days back in which a fix is suggested
for the TLLI mismatch. I had similar problems and they were solved
after applying that patch. The problem, as far as I found it, is that
SGSN is translating the foreign TLLI to a local TLLI (which is fine),
but later on rechecks the foreign TLLI for existence (which is not
fine, because the local variant exists). In my patch I convert all
TLLI to local before doing a check so previously created local TLLI's
are matched to the correlated foreign TLLI.
Regards,
Frank
I use OpenBSC/GPRS (sw version only few weeks
old) with nanoBTS and
this works well mith many mobile devices. With Nokia devices,
however, I do not get a PDP context. Here is an osmo-sgsn trace of
Nokia E65:
This is very likely a problem related to TLLI state tracking and LLC
sequence numbers. We have seen this for probably something like one
year in OsmoSGSN and sadly nobody has had enough of a problem with it to
actually debug it completely, fix it and contribute back a fix :/
4818
days inactive
4820
days old
2 comments
3 participants
participants (3)
-
Harald Welte -
Olaf Schulz -
VID - Frank Maas