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It is pretty unclear what codec items MNCC sends and receives exactly
when:
* Bearer Capabilities speech versions,
* 'payload message type' and
* the new SDP information
Include these items in MNCC rx and tx logging.
In msc_log_to_ladder.py, in sequence charts generated from an actual
osmo-msc log, also show all MNCC codec items.
Change-Id: I19ccffa2f9b627ad51fffd344ee6e75908d30295
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In order to send the MSC's RTP endpoint IP address+port in the initial
SDP, move the MGCP CRCX up to an earlier point in the sequence of
establishing a voice call.
Update the voice call sequence chart to show the effects.
Though the semantic change is rather simple, the patch is rather huge --
things have to happen in a different order, and async waits have to
happen at different times.
The new codec filter helps to carry codec resolution information across
the newly arranged code paths.
Related: SYS#5066
Change-Id: Ie433db1ba0c46d4b97538a969233c155cefac21c
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Same as voice_call_external_mncc.msc, but run with internal MNCC. Shows
some curious differences like the MNCC_LCHAN_MODIFY that internal MNCC
sends, but external doesn't.
Change-Id: Ic003322dc4e3fce24a8413688cfe18198a4dc08a
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Re-run the msc_log_to_ladder.py on an actual 2G-2G voice call log, to
see if anything changed in the meantime, to prepare for upcoming changes
to the sequencing of establishing voice calls.
Also shows recent improvements on picking up RTP ports from MGCP and
MNCC.
Change-Id: I9dcf980ad24d5921c291c9aada211b37f6f3db7f
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Because I will soon add an _internal_mncc one as well.
Change-Id: Ic90a93d749ea936a632a45e615007a58104eeedd
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(multiple changes in one patch because who cares about this script)
tweak regexes -- they worked ok, but some of the '[^:]' should really be
'[^:)]', and they also look happier that way.
don't skip RAN=NONE, so we also see messages before Complete Layer 3.
s/sip/mncc, to generally be valid for both internal and external MNCC.
pick up RTP port information from MGCP OK
pick up RTP port information from MNCC rx and tx
add --verbose flag, to be able to check whether the regex rules are
still working (getting any hits).
fix rule_imsi_detach: should return True to be counted in --verbose.
tweak comment 'Generated by...' to include the full git path.
Change-Id: If619182ba76c6b238a1fa105a3c3449d7f473dd1
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Both EXTRA_DIST and CLEANFILES had missing entries. It is easy to
forget to keep them up to date. Rather use wildcards to always pick up
all relevant files.
(Not adding *.dot because there are no .dot charts here, yet.)
Change-Id: I3a18e4608a310169d7c9cd9c1b8ac9015a990920
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Change-Id: I6ebc3a0555ef82e1c027ca75b45f8147a3e07ee6
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Fix typos and common misspellings in code comments and log messages.
Change-Id: Ie66b89065f2100c1d2125ce5a6c9b1d58df7c8ad
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Add voice_call_full.msc, generated from a real 2G<->3G voice call log fed to
msc_log_to_ladder.py.
The idea is to document how the voice call sequence of events changes in
upcoming patches.
Change-Id: I8a907d6a4ece1f3ad78da75a8c3e3e76afd5418d
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Add script that reads in an osmo-msc log output and extracts the interesting
information for displaying a sequence chart of voice call log, in mscgen
format.
I want to visualize how the sequence of messages changes across patches. It is
error prone to do it manually, and re-doing the sequence chart for every patch
(and patch rework) would be prohibitively time consuming.
Change-Id: I2e4d8778f7b83dee558517a9b23450b817ee325d
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mncc_fsm.[hc] were renamed to mncc_call.[hc] during patch review, which failed
to carry through to this sequence chart.
Also fix the MNCC_ST_* to MNCC_CALL_ST_* and MNCC_EV_* to MNCC_CALL_EV_*.
Change-Id: I03ee1b43ab95dca3c43fdb9e92dc158aad5a4203
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- add SIP messages, taken from OS#1683
- change some wording and clarify some message ordering
- have a separate sipcon1 and sipcon2 for the MO and MT sides
Change-Id: I6782e416dbd8ee88d093cbef722b0c5084f3865c
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3GPP TS 49.008 '4.3 Roles of MSC-A, MSC-I and MSC-T' defines distinct roles:
- MSC-A is responsible for managing subscribers,
- MSC-I is the gateway to the RAN.
- MSC-T is a second transitory gateway to another RAN during Handover.
After inter-MSC Handover, the MSC-I is handled by a remote MSC instance, while
the original MSC-A retains the responsibility of subscriber management.
MSC-T exists in this patch but is not yet used, since Handover is only prepared
for, not yet implemented.
Facilitate Inter-MSC and inter-BSC Handover by the same internal split of MSC
roles.
Compared to inter-MSC Handover, mere inter-BSC has the obvious simplifications:
- all of MSC-A, MSC-I and MSC-T roles will be served by the same osmo-msc
instance,
- messages between MSC-A and MSC-{I,T} don't need to be routed via E-interface
(GSUP),
- no call routing between MSC-A and -I via MNCC necessary.
This is the largest code bomb I have submitted, ever. Out of principle, I
apologize to everyone trying to read this as a whole. Unfortunately, I see no
sense in trying to split this patch into smaller bits. It would be a huge
amount of work to introduce these changes in separate chunks, especially if
each should in turn be useful and pass all test suites. So, unfortunately, we
are stuck with this code bomb.
The following are some details and rationale for this rather huge refactoring:
* separate MSC subscriber management from ran_conn
struct ran_conn is reduced from the pivotal subscriber management entity it has
been so far to a mere storage for an SCCP connection ID and an MSC subscriber
reference.
The new pivotal subscriber management entity is struct msc_a -- struct msub
lists the msc_a, msc_i, msc_t roles, the vast majority of code paths however
use msc_a, since MSC-A is where all the interesting stuff happens.
Before handover, msc_i is an FSM implementation that encodes to the local
ran_conn. After inter-MSC Handover, msc_i is a compatible but different FSM
implementation that instead forwards via/from GSUP. Same goes for the msc_a
struct: if osmo-msc is the MSC-I "RAN proxy" for a remote MSC-A role, the
msc_a->fi is an FSM implementation that merely forwards via/from GSUP.
* New SCCP implementation for RAN access
To be able to forward BSSAP and RANAP messages via the GSUP interface, the
individual message layers need to be cleanly separated. The IuCS implementation
used until now (iu_client from libosmo-ranap) did not provide this level of
separation, and needed a complete rewrite. It was trivial to implement this in
such a way that both BSSAP and RANAP can be handled by the same SCCP code,
hence the new SCCP-RAN layer also replaces BSSAP handling.
sccp_ran.h: struct sccp_ran_inst provides an abstract handler for incoming RAN
connections. A set of callback functions provides implementation specific
details.
* RAN Abstraction (BSSAP vs. RANAP)
The common SCCP implementation did set the theme for the remaining refactoring:
make all other MSC code paths entirely RAN-implementation-agnostic.
ran_infra.c provides data structures that list RAN implementation specifics,
from logging to RAN de-/encoding to SCCP callbacks and timers. A ran_infra
pointer hence allows complete abstraction of RAN implementations:
- managing connected RAN peers (BSC, RNC) in ran_peer.c,
- classifying and de-/encoding RAN PDUs,
- recording connected LACs and cell IDs and sending out Paging requests to
matching RAN peers.
* RAN RESET now also for RANAP
ran_peer.c absorbs the reset_fsm from a_reset.c; in consequence, RANAP also
supports proper RESET semantics now. Hence osmo-hnbgw now also needs to provide
proper RESET handling, which it so far duly ignores. (TODO)
* RAN de-/encoding abstraction
The RAN abstraction mentioned above serves not only to separate RANAP and BSSAP
implementations transparently, but also to be able to optionally handle RAN on
distinct levels. Before Handover, all RAN messages are handled by the MSC-A
role. However, after an inter-MSC Handover, a standalone MSC-I will need to
decode RAN PDUs, at least in order to manage Assignment of RTP streams between
BSS/RNC and MNCC call forwarding.
ran_msg.h provides a common API with abstraction for:
- receiving events from RAN, i.e. passing RAN decode from the BSC/RNC and
MS/UE: struct ran_dec_msg represents RAN messages decoded from either BSSMAP
or RANAP;
- sending RAN events: ran_enc_msg is the counterpart to compose RAN messages
that should be encoded to either BSSMAP or RANAP and passed down to the
BSC/RNC and MS/UE.
The RAN-specific implementations are completely contained by ran_msg_a.c and
ran_msg_iu.c.
In particular, Assignment and Ciphering have so far been distinct code paths
for BSSAP and RANAP, with switch(via_ran){...} statements all over the place.
Using RAN_DEC_* and RAN_ENC_* abstractions, these are now completely unified.
Note that SGs does not qualify for RAN abstraction: the SGs interface always
remains with the MSC-A role, and SGs messages follow quite distinct semantics
from the fairly similar GERAN and UTRAN.
* MGW and RTP stream management
So far, managing MGW endpoints via MGCP was tightly glued in-between
GSM-04.08-CC on the one and MNCC on the other side. Prepare for switching RTP
streams between different RAN peers by moving to object-oriented
implementations: implement struct call_leg and struct rtp_stream with distinct
FSMs each. For MGW communication, use the osmo_mgcpc_ep API that has originated
from osmo-bsc and recently moved to libosmo-mgcp-client for this purpose.
Instead of implementing a sequence of events with code duplication for the RAN
and CN sides, the idea is to manage each RTP stream separately by firing and
receiving events as soon as codecs and RTP ports are negotiated, and letting
the individual FSMs take care of the MGW management "asynchronously". The
caller provides event IDs and an FSM instance that should be notified of RTP
stream setup progress. Hence it becomes possible to reconnect RTP streams from
one GSM-04.08-CC to another (inter-BSC Handover) or between CC and MNCC RTP
peers (inter-MSC Handover) without duplicating the MGCP code for each
transition.
The number of FSM implementations used for MGCP handling may seem a bit of an
overkill. But in fact, the number of perspectives on RTP forwarding are far
from trivial:
- an MGW endpoint is an entity with N connections, and MGCP "sessions" for
configuring them by talking to the MGW;
- an RTP stream is a remote peer connected to one of the endpoint's
connections, which is asynchronously notified of codec and RTP port choices;
- a call leg is the higher level view on either an MT or MO side of a voice
call, a combination of two RTP streams to forward between two remote peers.
BSC MGW PBX
CI CI
[MGW-endpoint]
[--rtp_stream--] [--rtp_stream--]
[----------------call_leg----------------]
* Use counts
Introduce using the new osmo_use_count API added to libosmocore for this
purpose. Each use token has a distinct name in the logging, which can be a
globally constant name or ad-hoc, like the local __func__ string constant. Use
in the new struct msc_a, as well as change vlr_subscr to the new osmo_use_count
API.
* FSM Timeouts
Introduce using the new osmo_tdef API, which provides a common VTY
implementation for all timer numbers, and FSM state transitions with the
correct timeout. Originated in osmo-bsc, recently moved to libosmocore.
Depends: Ife31e6798b4e728a23913179e346552a7dd338c0 (libosmocore)
Ib9af67b100c4583342a2103669732dab2e577b04 (libosmocore)
Id617265337f09dfb6ddfe111ef5e578cd3dc9f63 (libosmocore)
Ie9e2add7bbfae651c04e230d62e37cebeb91b0f5 (libosmo-sccp)
I26be5c4b06a680f25f19797407ab56a5a4880ddc (osmo-mgw)
Ida0e59f9a1f2dd18efea0a51680a67b69f141efa (osmo-mgw)
I9a3effd38e72841529df6c135c077116981dea36 (osmo-mgw)
Change-Id: I27e4988e0371808b512c757d2b52ada1615067bd
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