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Change-Id: I6de1be0322ddbdc115074ebb6be2598ebf6c95db
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Prepare for Rhizomatica's subscriber on demand use case, in which the
network access is disabled by default for new subscribers, but the IMEI
is required in the HLR to find out which user has which IMSI. Due to the
network access being disabled, the location update request towards the
HLR fails and the MS gets rejected, so we need to get the IMEI early.
Related: OS#2542, OS#3755
Change-Id: I256224194c3b8caf2b58a88d11dccd32c569201f
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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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Comparing an array to null is not useful, because the expression
will always evaluate as true. Let's just always write SGs server
address and VLR name, no mater whether default values are used
or not, same as we do for the HLR address and port.
Change-Id: If045e42fca0315b0777eb86c44bf934ce58b340b
Fixes: CID#190871 Array compared against 0 (NO_EFFECT)
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It may happen that either the MS or an EUSE would become
unresponsive during a call independent SS session, e.g.
due to a bug, or a dropped message. In such cases, the
corresponding transaction would remain unfreed forever.
This change introduces a guard timer, that prevents keeping
'stalled' NCSS sessions forever. As soon as it expires, both
sides (i.e. MS and EUSE) are getting notified, and the
transaction is being released.
By default, the timer expires after 30 seconds. As soon as
either the MS, or an EUSE initiates any activity,
the watchdog timer is rescheduled.
The timeout value can be configured from the VTY:
msc
...
! Use 0 to disable this timer
ncss guard-timeout 30
Please note that changing the timeout value at run-time
doesn't affect the existing NCSS sessions, excepting the
case when the timer is disabled at run-time.
This change makes TC_lu_and_ss_session_timeout pass.
Change-Id: Icf4d87c45e90324764073e8230e0fb9cb96dd9cb
Related Change-Id: (TTCN) I3e1791773d56617172ae27a46889a1ae4d400e2f
Related: OS#3655
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Add an SGs interface (3GPP TS 29.118) to osmo-msc in order to support
SMS tunneling and Circuit Switched Fallback (CSFB)
Change-Id: I73359925fc1ca72b33a1466e6ac41307f2f0b11d
Related: OS#3615
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Related: OS#3189
Change-Id: Iee516b9cd7877b21207ce9a6d954109f19558163
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during code review, I completely overlooked this:
We've added the 'ipa-name', which identifies the MSC on the GSUP link to the
HLR, under the 'msc' section, while all other GSUP/HLR related config is under
the 'hlr' section.
Before we roll that out in a release, move it over to 'hlr'.
Related: OS#3355
Change-Id: I1a572865aa90c5fa43c6f57282a6e2b06776e425
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As a rudiment of OsmoNiTB, OsmoMSC is still involved in SMS
processing, storage (in SQLite DB), and routing (via SMPP).
In real networks this is done by the external entity called
SMSC (SMS Centre), while the MSC is doing re-encapsulation
of GSM 04.11 SM-TL (Transport Layer) payload (i.e. TPDU)
between SM-RL (Relay Layer) and MAP.
Since OsmoMSC itself is not a 'Network in The Box' anymore, it
makes sense to replicate the 'traditional' behaviour of MSC.
The problem is that this behaviour cannot co-exist with the
current implementation, so the key idea is to rip out the
local SMS storage and routing from OsmoMSC, and (re)implement
it in a separate process (OsmoSMSC?).
As a temporary solution, this change introduces a 'kill-switch'
VTY option that enables routing of SMS messages over GSUP
towards ESME (through VLR and HLR), but breaks the local
storage and routing. This is why it's disabled by default.
As soon as we move the SMS processing and storage away from
OsmoMSC, this behaviour would be enabled by default, and
the VTY option would be hidden and deprecated. At the moment,
this option basically does nothing, and will take an effect
in the follow-up changes.
Change-Id: Ie57685ed2ce1e4c978e775b68fdffe58de44882b
Related: OS#3587
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osmo-mgw I98a9f1f17a1c4ab20cea3b08c7d21663592134d6 broke the build here. Fix
that.
Change-Id: I20e37c5228928b67e67f16aef0eb2930d21ef60a
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Add a 'ipa-name' VTY command which overrides the default IPA name
used by the MSC. This is a prerequisite for inter-MSC handover.
Related: OS#3355
Change-Id: I317d6c59f77e92fbb2b875a83dc0ec2fa5cb6006
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So far the only way to use external MNCC is to pass the -M cmdline arg:
osmo-msc -M /path/to/socket
However, the osmo-msc.service file for systemd is installed by 'make install',
and hence it is quite impractical to depend on such a config item to be
required in the service file:
- It defies any scheme an operator may have in place to compose the
osmo-msc.cfg file -- this option doesn't go in the .cfg file but needs
separate action to add to the installed service file.
- After a make install or package upgrades / re-installations, this option will
be plain overwritten silently, or lead to the need for resolving file
conflicts.
The initial spark for this came from configuring the 35c3 GSM from cfg
templates.
Change-Id: I2ec59d5eba407f83295528b51b93678d446b9cee
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I want to add 'mncc internal' and 'mncc external' commands, and IMHO makes most
sense to have a common 'mncc' keyword to start MNCC config commands with. To
put it in terms of VTY online help:
OsmoMSC(config-msc)# mncc ?
internal Use internal MNCC handler
external Use internal MNCC handler
guard-timeout Set global guard timeout
So far only the 'guard-timeout' exists, I want to add 'internal' and 'external'
in a subsequent commit.
Keep the old command 'mncc-guard-timeout' as deprecated alias. That means it
still works from old config files, but online documentation will omit it.
On 'write', write back the new format instead.
Rationale: see I2ec59d5eba407f83295528b51b93678d446b9cee
Change-Id: I52d69af48e1ddc87b3fb54bf66a01b1b8cbf5abe
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It needs to work whether SMPP,Iu are enable or disabled, hence a bit more
wildcarding than one might expect.
Change-Id: I3a8c50d8d555b6b948d97d6412e17594ee439de0
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