In order to reuse the existing bssgp_tx_* functions without pulling
in the dependencies of gprs_bssgp.c, we have to move those functions
to gprs_bssgp_util.c
Furthermore, we can remove gbprox_nsi and replace it with bssgp_nsi,
and we can do proper processing of BVC-RESET messages coming from
the SGSN on the signalling BVC. In that case we need to send RESET
messages to all the BSS.
BSSGP stores a pointer to the Cell Identifier IE in msgb->cb, which
is later used by the GMM layer to identify the cell that has sent a
given message.
This now also means that the gsm_04_08_gprs.c code is free of any
legacy references to msg->trx or struct gsm_bts.
We now expect the highest level (actual SGSN GMM code) to know
all identifiers for every element in the protocol stack, i.e.
TLLI, SAPI, BVCI and NSEI. The layer-inetrnal state is looked
up based on those identifiers.
The reason for this is to ensure only the highest level state
needs to be persistent, while everything else can be regenerated
dynamically (e.g. in a SGSN restart)
The ida of the Gb proxy is to aggregate Gb links with a number of BSS
and then present all the BSSGP-VC's together inside one NS-VC to the
actual SGSN.
The code is not yet expected to be complete.
Harald Welte