GPRS issue after idle

historical

Hi!
I tested the patch but the problem still exists :(
Here is the new log from sgsn : http://pastebin.com/3PBKQwR5
If it helps, I am using an iPhone 4 with OpenBSC running under Debian 6 i686
VMWare.

-----Original Message-----
From: openbsc-bounces at lists.osmocom.org
[mailto:openbsc-bounces at lists.osmocom.org] On Behalf Of Harald Welte
Sent: Thursday, August 04, 2011 8:14 PM
To: Seungju Kim
Cc: openbsc at lists.osmocom.org
Subject: Re: GPRS issue after idle

Hi!

On Tue, Aug 02, 2011 at 02:30:14AM +0900, Seungju Kim wrote:
> Hello,I got everything up and running. Including EDGE data.
> 
> The throughput of the data from the osmo-sgsn is pretty good. But 
> recently I have spotted a problem with the SGSN.
> 
> The sgsn loses the phones SNDCP entity after idling or making a phone
call.
> http://pastebin.com/2W9dZdvW

Interesting.  I have not yet observed this, as most likely my phones don't
include the "PDP Context Status IE" (TS 24.008 / 10.5.7.1).

Using this IE, the phone can tell the network "I think I still have PDP
contexts for the following NSAPIs active".  The network  then checks if it
has the smae view, and silently deletes all PDP contexts for other NSAPIs.

It seems that the current code is interpreting the IE the wrong way.

We interpret it as an uint16_t, do ntohs() and it is 0x2000.
Apparently NSAPI 5 was active befor (your log snippet is a bit short):

<0002> gprs_gmm.c:884 Dropping PDP context for NSAPI=5 due to PDP CTX STATUS
IE= 0x2000 <0014> sgsn_libgtp.c:212 Delete PDP Context <0014>
sgsn_libgtp.c:389 PDP Context was deleted

If I'm looking at Chapter 10.5.7.1, it seems the encoding is a bit odd, i.e.
actually the byte ordering is little endian!

Can you try the patch below and see if the problem is fixed?

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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