Support of AoverIP (AOIP) in osmo-bsc

[Bindhu Anjaneya]

Hi,

>The better way to do this, from my point-of-view, is to follow what we have done for the Osmo-Iuh code (osmo-hnbgw, and IuCS/PS for
>OsmoCSCN/OsmoSGSN):
>
>* use the SUA support of libosmo-sccp, including its SCCP-User-SAP
 > that it provides towards applications
>
>This way, OsmoBSC uses the most simple SIGTRAN variant SUA towards an external signalling gateway, and doesn't have to bother with the more complex stacks like M3UA, M2UA, M2PA (all including SCCP).

Though the above approach is the simplest way, this implementation will not be in compliance with 3GPP specification, this would also introduce a hop between BSC and MSC on the A-Interface. 
So my suggestion is for Osmo-bsc to be 3GPP compliance, the SIGTRAN stack BSSAP/SCCP/M3UA/SCTP/IP need to be implemented in Osmo-bsc. 
To achieve this:-
Existing SCCP - need to be upgraded if needed
M3UA - need to be developed may be as a separate library

We can introduce a compile time flag if we need to differentiate between the support for SCCP/M3UA and SUA.

Let me know your inputs

Regards,
Bindhu

-----Original Message-----
From: Harald Welte [mailto:laforge at gnumonks.org] 
Sent: Monday, March 14, 2016 8:40 PM
To: Bindhu Anjaneya <Bindhu.Anjaneya at radisys.com>
Cc: Holger Freyther <holger at freyther.de>; openbsc at lists.osmocom.org
Subject: Re: Support of AoverIP (AOIP) in osmo-bsc

Hi Bindhu,

On Mon, Mar 14, 2016 at 01:20:11PM +0000, Bindhu Anjaneya wrote:
> As part of design consideration, we are analyzing Erlang osmo-ss7 
> SIGTRAN Stack(SCCP,M3UA,SCTP) to integrate with osmo-bsc (bsc only 
> mode).
> We are also analyzing the option of retaining the currently used 
> libosmo-SCCP, kernel SCTP and use the M3UA from the osmo-ss7.

in terms of the encapsulation of the A-over-IP, I would suggest to not rely on the Erlang implementations that we have.  This would import a dependency on a rather large code base for a limited functionality, and it doesn't really resolve the question on how to interface the osmo-ss7 erlang code from C code such as OsmoBSC.

The better way to do this, from my point-of-view, is to follow what we have done for the Osmo-Iuh code (osmo-hnbgw, and IuCS/PS for
OsmoCSCN/OsmoSGSN):

* use the SUA support of libosmo-sccp, including its SCCP-User-SAP
  that it provides towards applications

This way, OsmoBSC uses the most simple SIGTRAN variant SUA towards an external signalling gateway, and doesn't have to bother with the more complex stacks like M3UA, M2UA, M2PA (all including SCCP).

In this way,
* osmo-bsc has a clean interface, and re-uses the code from the Iu
  related projects
* you can use osmo-ss7 or any other signalling gateway (FOSS or
  proprietary) to move towards M3UA or any other transport stack.

Let me know what you think about the above-mentioned approach.

Please note the SUA code in libosmo-sccp is also still limited at this point, in a sense that it doesn't implement the ASP-Management state machines yet.  This would still have to be added.  If it is added to libosmo-sccp, then all useres, whether IuCS, IuPS or AoIP will benefit from that.

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