MSC split: is_siemens_bts() in libmsc/gsm_04_08.c / conn->bts vs. lchan->ts->trx->bts

This is merely a historical archive of years 2008-2021, before the migration to mailman3.

A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/OpenBSC@lists.osmocom.org/.

Harald Welte laforge at gnumonks.org
Sun Feb 14 11:07:19 UTC 2016


Hi Neels,

as Holger has indicated, we definitely need to keep BS-11 compatibility.

On Tue, Feb 09, 2016 at 10:30:15PM +0100, Neels Hofmeyr wrote:
> Who is this Mister PCI anyway? ;)

I just Googled 'Siemens Abis MRPCI' and found an old question + response
I posted some years ago:
http://www.erlang.com/forum/erlang/thread.htx?thread=3168

I don't think it neccessarily needs to be sent at a very specific point
in time, but it needs to be sent after dedicated channel establishment
and before T_MSRFPCI expires.  However, to put reasonable values into
the message, we need to know the classmark of the MS.

> The gsm48_handle_paging_resp() function leads me to another, more general
> question: often, there are two bts pointers around, namely the
>   gsm_subscriber_connection->bts
> as well as the
>   lchan->ts->trx->bts
> Are these typically/always/never expected to be the same bts struct?

I would assume that both pointers are the same in all cases.

> (In this function, both bts pointers are used, and I'd like to understand why.)

When I created OpenBSC, we only had the lchan->ts->trx->bts pointers,
and we had the subscriber point directly to the lchan.  IIRC, Holger
later introduced the subscriber_connection when he created OsmoBSC.

So there might be some cases where a field was not removed but could be
removed?

The lchan/ts/trx/bts hierarchy is always present when a dedicated
channel is established.  It is a very BSC-centric data structure.

The subscriber/subscriber_conn is a MSC-centric data structure.  And
basically on the BSC side we have lchan's that are mapped over the A
interface to a subscriber_conn on the MSC side.  Thus, the MSC shouldn't
referernce the lchan.

-- 
- 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)



More information about the OpenBSC mailing list