12 Jul
2017
12 Jul
'17
3:35 p.m.
On Tue, Jul 11, 2017 at 05:49:47PM +0200, Alexander Couzens wrote:
recently my modem with an already known SIM got a
location update
reject, because the procedure timed out. So I looked more
into the location updates.
How openbsc location update works:
MS Network
LOC REQ ->
<- Identity Req IMSI
Identity Resp IMSI ->
<- Identity Req IMEI
Identity Resp IMEI ->
<- LOC ACCEPT
OpenBSC is using a Timeout (5 sec) for the completion of location
update.
One important fact here is that we have completely re-implemented location
updating when introducing the VLR + HLR, since the openbsc.git vlr_2G branch.
This uses brand new finite state machines with capabilities for individual
timers for each step. These could be refined, but the point is that we're
definitely not going to revisit the old location updating code.
You may take a look at how the new code reacts to timeouts.
https://git.osmocom.org/openbsc/tree/openbsc/src/libmsc/subscr_conn.c?h=aoip
suggests that on conn timeout, we simply and bluntly close the connection
without answering with 'Roaming not allowed' now. Also see
https://git.osmocom.org/openbsc/tree/openbsc/tests/msc_vlr/msc_vlr_test_ms_…
which tests timeout explicitly. There's also an HLR timeout test in that dir.
https://git.osmocom.org/openbsc/tree/openbsc/tests/msc_vlr?h=aoip
There are also various LU reject causes tested in e.g.
https://git.osmocom.org/openbsc/tree/openbsc/tests/msc_vlr/msc_vlr_test_hlr…
If you'd like to refine LU reject messages, go for the vlr_2G branch (to use
the OsmoNITB with a separate OsmoHLR) or the aoip branch (to use the entirely
new OsmoMSC with separate OsmoSTP, OsmoHLR, OsmoBSC and a real A-interface).
The aoip branch constitutes what are going to be the new osmo-msc and osmo-bsc
master branches in the split repositories.
~N