[RFC] Changes to the lchan and BSC/MSC split

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Holger Freyther zecke at selfish.org
Wed Sep 30 13:24:00 UTC 2009


On Wednesday 30 September 2009 14:08:16 Sylvain Munaut wrote:
> Hi,
> 
> On Wed, Sep 30, 2009 at 4:12 AM, Holger Freyther <zecke at selfish.org> wrote:
> > I would like to implement the following.
> >        - Remove the refcount from lchan
> >        - Replace it with the "transaction" concept. On certain 04.08
> > messgaes (e.g. paging response, various MM messages) open a transaction
> > from BSC to MSC code. The channel is bound to the transaction.
> 
> Are you talking about the transaction in transaction.c ?

Partially yes. I'm talking about GSM08.08 "§ 3.2.1.32 COMPLETE LAYER 3 
INFORMATION". In which the MSC is getting informed that it is in charge now 
(only the MSC is closing the SCCP connection...)

> 
> Because for SMS for examples, we re-use the same lchan for consecutive
> transactions when delivering multiple SMS back to back and your
> approach would make that impossible if I understand correctly ?

Well, it is up to the MSC to decide when to close the "transaction"/SCCP 
connection. So if the MSC policy is to send multiple SMS it will still work. 

The general change is that the MSC is completely controlling the lchan 
lifetime. If the radio resource is freed, but the MSC still occupies the 
channel it will not be reused.

holger




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