FW: OpenBSC on 3rd party MSC

historical

Related: https://osmocom.org/issues/3476
"osmo-bsc manual needs to explain the AoIP config 'cs7 instance'"

Note that the osmo-msc manual has a similar section: http://ftp.osmocom.org/docs/latest/osmomsc-usermanual.pdf
"See OsmoMSC manual 'Running OsmoMSC' / 'Configure primary links' -- the OsmoBSC manual needs a similar section"

A cs7 section I found in one of my test setups is:

cs7 instance 0
 point-code 0.23.3
 asp asp-clnt-msc-0 2905 0 m3ua

If you're using SCCPlite, it could look something like

cs7 instance 0
 sccp-timer ias 90
 point-code format 24
 point-code 1196
 asp asp-clnt-msc-0 5000 0 ipa
  remote-ip 123.45.0.200
  local-ip 123.45.49.100
 as as-clnt-msc-0 ipa
  asp asp-clnt-msc-0
  routing-key 0 1196
  point-code override dpc 100
 sccp-address remote_msc
  point-code 100
msc 0
 msc-addr remote_msc

I hope that helps? Configuring cs7 is not trivial, maybe would make sense to
book some support hours and provide direct access so that developers can help
you directly...

~N

On Tue, Apr 23, 2019 at 05:00:15PM -0400, wyao at corrections.com wrote:
> Hello everyone,
> 
> I am still not be able to figure out how to configure the A interface on the
> OsmoBSC side to talk to MSC, I will really appreciated if someone could
> share a similar configuration. Or if someone could point me to the right
> document, I looked through the OsmoBSC user
> manual(http://ftp.osmocom.org/docs/latest/osmobsc-usermanual.pdf) and could
> not find the A interfaces config section.
> 
> Thanks,
> Weiqi
> 
> -----Original Message-----
> From: wyao at corrections.com <wyao at corrections.com> 
> Sent: Tuesday, April 16, 2019 12:02 PM
> To: 'Harald Welte' <laforge at gnumonks.org>
> Cc: OpenBSC at lists.osmocom.org
> Subject: RE: OpenBSC on 3rd party MSC
> 
> Thanks Harald for your reply,
> 
> Looks like the issue is the connection between OsmoBSC and my MSC.
> 
> I checked again on my MSC side, looks like it interfaces with softBSC on
> AoIP, connect to BSC port 2427 and 5000. So basically it just require a
> softBSC IP address to be able to connect. 
> 
> I found an example cfg called osmo-bsc-mgcp.cfg under the OpenBSC folder,
> but I have no clue if this is the right one to modify. I will appreciate if
> you can provide some example BSC configuration like this. Also, Should I
> still keep the OsmoSTP?
> Thanks again!
> 
> Regards,
> Weiqi
> 
> -----Original Message-----
> From: Harald Welte <laforge at gnumonks.org>
> Sent: Saturday, April 13, 2019 5:51 AM
> To: wyao at corrections.com
> Cc: OpenBSC at lists.osmocom.org
> Subject: Re: OpenBSC on 3rd party MSC
> 
> Hi Weiqi,
> 
> On Thu, Apr 11, 2019 at 04:00:08PM -0400, wyao at corrections.com wrote:
> > I am working on get OpenBSC connected to a 3rd party MSC, I read from 
> > the Osmo document that I can use the bsc only mode and the osm-bsc 
> > instead of the osmo-nitb.
> 
> This is correct.  However, the terminology is a bit messed-up.  So it's best
> to not use OpenBSC anymore but alsways call it OsmoBSC.
> 
> > Currently I had osmo-trx-uhd, osmo-bts-trx, osmo-bsc, and osmo-stp 
> > configured and and running,
> 
> sidenote: You will have to add osmo-mgw for handling voice calls later on,
> but that is irrelevant until you get the signalling plane up and running.
> 
> > but I see a lot of below error logs in the osmo-stp console:
> > 
> > DLSS7 <000c> osmo_ss7.c:1468 asp-asp-dyn-0: xua_srv_conn_cb(): 
> > sctp_recvmsg() returned 56 (flags=0x80) DLM3UA <000f> m3ua.c:722
> > asp-asp-dyn-0: Received M3UA Message (XFER:DATA) DLM3UA <000f>
> > m3ua.c:541 asp-asp-dyn-0: m3ua_rx_xfer DLM3UA <000f> m3ua.c:580
> > asp-asp-dyn-0: m3ua_rx_xfer(): M3UA data header: opc=337=0.42.1
> > dpc=185=0.23.1
> > DLSS7 <000c> osmo_ss7_hmrt.c:278 m3ua_hmdc_rx_from_l2(): 
> > dpc=185=0.23.1 not local, message is for routing
> > DLSS7 <000c> osmo_ss7_hmrt.c:258 MTP-TRANSFER.req for DPC 185: no route!
> 
> Your SS7 routing seems to be misconfigured.  The STP receives SCCP from
> OsmoBSC, but there's no (currently active/working) route for the MSC.  Hence
> the message cannot be routed and is discarded.
> 
> > <0007> a_reset.c:106 A-RESET(msc-0)[0xb76ce0]{DISC}: (re)sending 
> > BSSMAP
> RESET message...
> > <0007> osmo_bsc_sigtran.c:93 Sending RESET to MSC: 
> > RI=SSN_PC,PC=0.23.1,SSN=BSSAP
> 
> The BSC is trying to send a BSSMAP RESET to the MSC, but there's no
> response.
> 
> > Can anyone identify what is the issue here? 
> 
> It's a SS7 routing / SIGTRAN configuration issue.  You need to make sure the
> osmo-stp and osmo-bsc SS7 related configuration exactly matches the
> configuration on the MSC side.
> 
> Also, depending on your SIGTRAN network setup, you may not even need
> osmo-stp.
> That would be the case e.g. if the MSC or an existing STP in your core
> network would already provide a M3UA SGW functionality to which the AS/ASP
> of OsmoBSC can connect to.
> 
> It's really not possible to give you an easy answer without fully
> understanding your core networks SS7/SIGTRAN configuration, routing,
> addresses, point codes, etc.
> 
> SIGTRAN and SS7 are rather complex protocol stacks themselves.  There's
> little we can do on the Osmocom side to avoid that.  We can just provide all
> the possible settings/options so you can configure it to match your network
> topology.
> 
> Regards,
> 	Harald
> -- 
> - Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
> ============================================================================
> "Privacy in residential applications is a desirable marketing option."
>                                                   (ETSI EN 300 175-7 Ch. A6)
> 
> 

-- 
- Neels Hofmeyr <nhofmeyr at sysmocom.de>          http://www.sysmocom.de/
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