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channel_release: First attempt to update the doc to new code.

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This commit is contained in:
Holger Hans Peter Freyther
2010-09-03 15:34:12 +08:00
parent afdb522ced
commit 6262643b45
1 changed files with 41 additions and 22 deletions
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61
openbsc/doc/channel_release.txt
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@@ -31,46 +31,65 @@ GSM 04.08 3.4.13: RR connection release procedure
== Implementation in OpenBSC ==
THIS IS OUTDATED and will be updated...
There are two possible reasons a gsm_subscriber_connection
will be released. One is a network failure, the other is
the completion of an operation/transaction.
chan_alloc.c:lchan_auto_release()
* checks if use count still > 0 (abort)
* calls gsm48_send_rr_release()
* which calls rsl_deact_sacch()
* calls rsl_release_request()
* which sends RLL Link Release request
=== Failure ===
The BSC API will call the gsm_04_08.c:gsm0408_clear_request callback
and the MSC part will release all transactions, operations and such
and the channels will be released as error case.
=== Success ===
Every time an 'operation' or 'transaction' is finished msc_release_connection
will be called and it will determine if the gsm_subscriber_connection can
be released.
In case it can be released bsc_api.c:gsm0808_clear will be called
which will release all lchan's associated with the connection. For the
primary channel a SACH Deactivate will be send with the release
reason NORMAL RELEASE.
bsc_api.c:gsm0808_clear
* Release a channel used for handover
* Release the primary lchan with normal release, SACH deactivate
chan_alloc.c:lchan_release(chan, sach_deactivate, reason)
* Start release procedure. It is working in steps with callbacks
coming from the abis_rsl.c code.
* Release all SAPI's > 0, wait for them to be released
* Send SACH Deactivate on SAPI=0
* Finally Release the channel
RX of RELease INDication:
* call rsl_rf_chan_release() (send RF_CHAN_REL)
* Calls internal rsl_handle_release which might release the RF.
* Informs chan_alloc.c about the release with
rsl_lchan_rll_release.
RX of RELease CONFimem:
* call rsl_rf_chan_release() (send RF_CHAN_REL)
* Calls internal rsl_handle_release which might release the RF.
* Informs chan_alloc.c about the release with
rsl_lchan_rll_release.
* RX of RF_CHAN_REL_ACK
* call lchan_free()
* subscr_put()
* delete release_timer
=== Integration with SMS ===
* RX of CP_ERROR or unimplemented MT
* trigger trans_free() which will lchan_auto_release()
* trigger trans_free() which will msc_release_connection()
* CP TC1* expired while waiting for CP-ACK
* trigger trans_free() which will lchan_auto_release()
* trigger trans_free() which will msc_release_connection()
* RX of RP_ERROR
* trigger trans_free() which will lchan_auto_release()
* trigger trans_free() which will msc_release_connection()
* TX of CP-ACK in MT DELIVER
* trigger trans_free() which will lchan_auto_release()
* trigger trans_free() which will msc_release_connection()
* RX of CP-ACK in MO SUBMIT
* trigger trans_free() which will lchan_auto_release()
* trigger trans_free() which will msc_release_connection()
* RX of RP-ACK in MT DELIVER (and no more messages)
* trigger rsl_release_request() for SAPI3
* RX of RP-SMMA in MT DELIVER (and no more messages)
* trigger rsl_release_request() for SAPI3