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
For hysterical raisins, there are some header files that contain few
declarations, and where the name doesn't reflect the content. Combine them to
new msc_common.h:
- common.h
- common_cs.h
- osmo_msc.h
Change-Id: I9e3a587342f8d398fb27354a2f2475f8797cdb28
osmo-msc still had large amounts of dead code that came along from
openbsc.git. This commit removes a lot of it, mostly stuff relevant
only to the BSC side of things (or even GPRS).
Change-Id: I247def85da2dc3ec461389fb74414a0d964e7e3c
Related: OS#2528
The MSC should not fiddle with low-level SI details like rest octets
anyway. Unfortunately simply removing the header is impossible as it
causes massive fallout due to missing includes. Fixed it as well.
The only other parameter which required removal is cell_ro_sel_par which
is not referenced anywhere in the code anyway.
Change-Id: Ibff77330de056fad4288cd4c48d016aad8105354
This was originally a long series of commits converging to the final result
seen in this patch. It does not make much sense to review the smaller steps'
trial and error, we need to review this entire change as a whole.
Implement AoIP in osmo-msc and osmo-bsc.
Change over to the new libosmo-sigtran API with support for proper
SCCP/M3UA/SCTP stacking, as mandated by 3GPP specifications for the IuCS and
IuPS interfaces.
From here on, a separate osmo-stp process is required for SCCP routing between
OsmoBSC / OsmoHNBGW <-> OsmoMSC / OsmoSGSN
jenkins.sh: build from libosmo-sccp and osmo-iuh master branches now for new
M3UA SIGTRAN.
Patch-by: pmaier, nhofmeyr, laforge
Change-Id: I5ae4e05ee7c57cad341ea5e86af37c1f6b0ffa77
Fixes regression probably introduced in c696cc28.
For bts>0 logging doesn't show bts number correctly when printing lchan
identification string - it will always show it as "bts=0". The reason for
this is that the identification string is cached before bts->nr value is
set to a proper value.
This patch sets bts->nr as part of the first step of the bts structure
initialization, before caching happens thus making sure the cached
identification string is cached with the correct values.
Change-Id: I61c18a7f021fcb1ec00d34a745f4e3ab03416c2d
Original libvlr code is by Harald Welte <laforge@gnumonks.org>,
polished and tweaked by Neels Hofmeyr <nhofmeyr@sysmocom.de>.
This is a long series of trial-and-error development collapsed in one patch.
This may be split in smaller commits if reviewers prefer that. If we can keep
it as one, we have saved ourselves the additional separation work.
SMS:
The SQL based lookup of SMS for attached subscribers no longer works since the
SQL database no longer has the subscriber data. Replace with a round-robin on
the SMS recipient MSISDNs paired with a VLR subscriber RAM lookup whether the
subscriber is currently attached.
If there are many SMS for not-attached subscribers in the SMS database, this
will become inefficient: a DB hit returns a pending SMS, the RAM lookup will
reveal that the subscriber is not attached, after which the DB is hit for the
next SMS. It would become more efficient e.g. by having an MSISDN based hash
list for the VLR subscribers and by marking non-attached SMS recipients in the
SMS database so that they can be excluded with the SQL query already.
There is a sanity limit to do at most 100 db hits per attempt to find a pending
SMS. So if there are more than 100 stored SMS waiting for their recipients to
actually attach to the MSC, it may take more than one SMS queue trigger to
deliver SMS for subscribers that are actually attached.
This is not very beautiful, but is merely intended to carry us over to a time
when we have a proper separate SMSC entity.
Introduce gsm_subscriber_connection ref-counting in libmsc.
Remove/Disable VTY and CTRL commands to create subscribers, which is now a task
of the OsmoHLR. Adjust the python tests accordingly.
Remove VTY cmd subscriber-keep-in-ram.
Use OSMO_GSUP_PORT = 4222 instead of 2222. See
I4222e21686c823985be8ff1f16b1182be8ad6175.
So far use the LAC from conn->bts, will be replaced by conn->lac in
Id3705236350d5f69e447046b0a764bbabc3d493c.
Related: OS#1592 OS#1974
Change-Id: I639544a6cdda77a3aafc4e3446a55393f60e4050
This is the first step in creating this repository from the legacy openbsc.git.
Like all other Osmocom repositories, keep the autoconf and automake files in
the repository root. openbsc.git has been the sole exception, which ends now.
Change-Id: I9c6f2a448d9cb1cc088cf1cf6918b69d7e69b4e7
When we are performing Rx sensitivity testing on a BTS, we want to
deactivate the connection failure criterion / radio link timeout, i.e.
no matter how many SACCH frames in uplink are failed to decode, the BTS
should never close the channel.
OsmoBTS Change-Id I736f21f6528db5c16fa80cdb905af20673797be5 covers a way
how this behavior can be requested from the BTS via an OML attribute.
This patch adds support to the BSC to actually set that attribute.
Do not use this in production networks, as the BTS will keep open radio
channels indefinitely even if the phone is gone and no longer
transmitting anything. This is a pure testing feature.
Change-Id: I6cb94e0f024934f7baeeb728ca9ed3042fbf16d2
To support segmented SI2quater as per 3GPP TS 44.018 we'll have to
support multiple SI messages (up to 16 for SI2q) for a given type in
contrast to existing 1:1 mapping:
* expand storage space to hold up to 16 SI messages (spec limit)
* add assertions for budget calculations
* generate multiple SI2q messages
* adjust SI2q-related tests
* use precise check for number of SIq messages instead of approximate
estimation
Change-Id: Ic516ec9f0b821557d9461ae9f1c0afdd786f3b05
Related: OS#1660
* move SI2quater related defines to shared header
* add define from OsmoBTS which checks for presence of a given SI
message in gsm_bts struct. Rename it to avoid conflicts with OsmoBTS
code and to match naming conventions of similar macros.
Change-Id: I11432c93c772d1ead6d45a7bb0f1d13d492c82f1
Related: OS#1660
In addition to compile-time defined BTS model features we also need
run-time BTS features reported by BTS via OML. This should be shared by
BSC and BTS. To accommodate for this, add following:
* features bitvec to gsm_bts struct
* features descriptions
* comments to avoid confusion between 2 feature sets
* helper functions to set/query particular feature
* upper boundary on number of supported features and assertion for it
Change-Id: I02bd317097ba66585c50ebd4e8fc348f6dc3dad9
Related: OS#1614
Since commit b4999b60d4 we created PCU
sockets at hard-coded paths in the filesystem by default for all BTSs.
This is inflexible and prevents the use of multiple BSC instances on a
single filesystem, or the placement of the sockets in a more secure
location than /tmp.
The new approach with this patch is that
* no PCU sockets are created by default
* only for those BTSs where a 'pcu-socket' is configured via VTY,
the socket will actually be created
Change-Id: Ie9079470584777dcc31f85f9bf0808f479156ccb
Closes: OS#2293
The gsm_data_shared.h header is installable and used by OsmoBTS so it
should not include any private (non-installable headers) to avoid
OsmoBTS' build failures.
Change-Id: Ic25031101fc01bd732fe691132c081ad05fa6a4b
In preparation for extended SI2q messages:
* add SI2q-specific accessor macro
* add *_offset variables to gsm_bts struct
* internalize memory check while generating rest octets - introduce
budget concept (number of bits available in a given message)
* internalize *arfcn_size() functions as they are not needed outside of
si2q_num() anymore
* change rest octets generation to work with gsm_bts struct directly
* do not generate rest octets if no SI2q is necessary
* adjust unit tests accordingly (cosmetic changes only to avoid
regressions)
Requires: I92e12e91605bdab9916a3f665705287572434f74 in libosmocore
Change-Id: Ib554cf7ffc949a321571e1ae2ada1160e1b35fa6
Related: RT#8792
* use define for number of attributes instead of magic number
* add sub_model to gsm_bts struct
* expand number of BTS features
* mark attributes parameter to abis_nm_get_attr() as const
Change-Id: I7ecb0c4339530d3a8354a2f94b34063dda87e030
Related: OS#1614
* move value_string definition and corresponding functions for BTS type
to shared header to make it re-usable by OsmoBTS
* use consistent function naming
* add similar functions for BTS variant
* add enum to be used by OML Attribute Reporting to distinguish between
type, variant and other info
Change-Id: Ida94725a6fce968443541e3526f48f13758031fd
Related: OS#1614
Previously it was only in gsm_bts_model which is not initialized on BTS
side. It's more convenient to have it in the struct which is available
to BTS as well.
Change-Id: I54fde8c4ccd5d994af08074f5864446e79a93a25
Related: OS#1614
Supporting SI2quater as per 3GPP TS 44.018 will require chnages to the
way System Information is stored because it uses 1:n instead of 1:1
mapping between SI type and generated SI content. This should not affect
other SI types though. To facilitate this transition:
* convert the code to always use GSM_BTS_SI helper instead of accessing
buffer directly
* make helper more robust by adding extra parenthesis
* add similar helper for gsm_lchan
* add function estimating number of SI2quater message to hold configured
number of (U|E)ARFCNs
* add SI2q index/count fields and pass them to rest_octets generator
explicitly
* internalize buffer access in generate_si* functions
Change-Id: I74e4e3cb86364cec869a1472a41b4a95af0d50dd
Related: RT#8792
* add version string to gsm_bts
* add PCU version string to gsm_bts
* rename GSM_BTS_TYPE_OSMO_SYSMO -> GSM_BTS_OSMOBTS to avoid confusion
between BTS model and variant
* add variant enum to gsm_bts_model using enum with variants for each
hw vendor of OsmoBTS
* show connected PCU version (if available) in vty via 'show bts'
This will come in handy when logging details regarding particular BTS
reported via OML, see:
Related: OS#1614
Change-Id: I6710d53115f34634a7b70969cc05fd5c72ff8ab2
When the BTS is configured to use a SuperChannel and it is using a
unix domain socket based transport towards the L2TP daemon, then
we must instruct the L2TP daemon to instruct the SIU to change the Abis
Lower Transport Mode using the ALTCRQ / ALTCRP L2TP signalling.
Change-Id: I672bfaa09c42fbeb0c8459f24b2222b952de954b
Add MS TIMING OFFSET (3GPP TS 48.058 § 8.4.8) and P offset (3GPP TS
45.010 § 1.2) which can be used to compute MS TO from known TA.
This will be used by osmo-bts (see
I4dfe5c48834a083e757d5de3236a02e15a238b28) to provide MS TO as part of
RSL MEASUREMENT RESULT.
Change-Id: I8bda57c8d6c15bbb803eca708931556dae118a00
Related: OS#1574
In some cases, when successive mobile originated calls are made, the LAPDm UA
message gets lost because the channel is relased to early. Too overcome the
problem we do not send release indications immediately. Instead a flag will be
set and the message stored and sent on the next TCH-RTS-IND.
This commit adds the required flag and the msg-buffer to struct gsm_lchan.
See also coresponding change in osmo-bts.git:
Change-Id Ie4f70c75f0137b4bd72d579b3a32575bac2fca38
This patch is is a slightly improved/reformatted version of:
95d1f15ad1
Change-Id: I15fc1ef8e9e83f009bde96de9a8e95702cffbce6
The SI3 rest octests contain a flag that indicates if early classmark
sending is allowed in this cell or not. So far we always set this to
one, now it is configurable using the 'early-classmark-sending' command
at the VTY node.
Change-Id: Ia0b1cc5ab45673f3da70c59ae8917eba343f9862
This is useful particularly in case where we deactivate PDCHs
which don't have a SACCH associated. The existin code would
always attempt to deactivate a SACCH even in those cases, leading
to the BTS responsding with related error messages.
Change-Id: Iaf46782329b38ba8f3d438e6c75c2d467b852734
Time zone used to be configurable per-BTS. In the upcoming MSC-split, no BTS
structures will be available on the MSC level. To simplify, drop the ability to
manage several time zones in a core network and place the time zone config on
the network VTY level, i.e. in gsm_network. If we are going to re-add fine
grained time zone settings, it should probably be tied to the LAC.
Adjust time zone VTY config code (to be moved to libcommon-cs in subsequent commit).
Adjust time zone Ctrl Interface code.
Change-Id: I69848887d92990f3d6f969be80f6ef91f6bdbbe8
Factor out encryption info from struct gsm_lchan as struct gsm_encr, placed in
common_cs.h.
Change-Id: I94015fb9dd511c37c1e3058a0963c780b3f700ac
Future: this will be used by libmsc's subscriber connection, for osmo-cscn.
Our existing OM2000 code for initializing all Managed Objects of a BTS
at startup was never complete. Rather than trying to fix the old-style
code, introudce a hierarchy of osmo_fsm's reflecting the full protocol
hand-shake and sequence of bringing up the individual MO's.
If this works out well, it mihgt make sense to convert the TS 12.21 OML
code for other BTS models, too.
Change-Id: I3e11b28ba22b8c227e0401e6207fdda5381dda8c
When DL DTX is active and silent period is in progress dtx.cache is
populated by SID UPDATE message which about to be scheduled next. If at
that moment FACCH message arrives (which have higher priority) we have
to send ONSET message to L1 but we can't invalidate cache with SID
UPDATE as it will be used for SID FIRST message to resume silent period
after FACCH transmission is over (provided there were no incoming voice
in between). Hence the necessity for separate buffer to store content of
FACCH message while we're sending ONSET to L1 while keeping SID UPDATE
cached.
Change-Id: I316e81af893b24766bf259baaed7a0be75a11694
Related: OS#1801
Value 4 used as magic number by both OpenBSC and OsmoBTS so it make
sense to add it to shared header. See
ebb483b69a5319e522ba5f713e9cb6f68a814a6a in osmo-bts for details.
Change-Id: I9c6ad68f4c6aa72d39ec7e5a6968b36ec20e79f4
- consolidate all DTX-specific things in a separate struct
- rename struct fields to better reflect meaning
- add pointer to DL FSM for AMR
- remove unused flag
- expand buffer to hold cached payload alongside with CMR/CMI
Change-Id: Idac8609faf9b5ced818fde899ccfc6ed0c42e8fd
Add flag to explicitly track the state of DTX DL for AMR HR whe
SID_FIRST_P1 has been sent to L1 already but no next frame available
yet: this can be followed by SID_FIRST_P2 or SID_FIRST_INH depending on
arrival of voice frame within next 60 ms.
Change-Id: Id28b07b8e83cfe5e84de48a2f124084036580cd4
In addition to RTP payload SID cache got to store CMR/CMI prefix. Extend
the buffer so it can fit in.
Change-Id: Ibd4a63604a82cad3ce65f0752bffefa4b083e1b3
Fixes: Coverity CID#149508
Add ts_is_tch() in gsm_data_shared.h/.c and use it to replace a switch on the
pchan in e1_config.c.
This patch is not due to an actual observed failure. A general grep for switch
on pchan turned up this instance that doesn't handle dyn TS properly. Hence
this patch is not actually tested with real equipment.
Change-Id: Ide4f156034bab77140d2d9a8c462d68ae6f0d6a6
Add vty function to explicitly set use of 4xRACH type of ack message for
PACKET CONTROL ACKNOWLEDGMENT. Previous hardcoded value (use RLC/MAC
control block) is used as a default.
This is handy for debugging issues related to Timing Advance in context
of GPRS.
Change-Id: Ie869ac0a82055110f1e3b875e246750c4e113336
Related: OS#1526
In struct gsm_lchan, add dyn.rqd_ref and dyn.rqd_ta. These save the Channel
Requested details across the PDCH deactivation dance.
abis_rsl.c: add static functions:
* dyn_ts_switchover*() for the various stages of switchover between pchans.
* pchan_for_lchant() to derive the desired pchan from the lchan type that was
set during lchan_alloc().
* rsl_chan_activate_lchan_as_pdch() to compose the simpler RSL CHAN ACT message
without introducing numerous special cases to the normal RSL CHAN ACT code.
In rsl_chan_activate_lchan(), detect and initiate required pchan switchovers if
requested pchan on a dyn TS differs.
In rsl_rx_rf_chan_rel_ack(), initiate or continue pchan switchovers after a
channel was released.
In rsl_rx_chan_act_ack(), notice that a switchover is complete.
In chan_alloc.c, add ts_subslots(): abis_rsl.c will need to know the number of
subslots per pchan, to verify that all lchans are free before dyn TS
switchover. The subslots_per_pchan[] array is static to lchan_alloc.c, and
since we need a non-trivial check for dyn TS anyway, add public ts_subslots()
to lchan_alloc.c, which also checks the current dyn pchan type.
Change-Id: I5c6bce13092a10204113d84678c587c65e35e4fd
For upcoming dynamic TS, the pchan choice for RSL De-/Activation is not
trivial. So in order to pass the desired pchan to generate the RSL chan_nr,
introduce gsm_lchan_as_pchan2chan_nr().
To avoid code dup, this requires decoupling the gsm_ts2chan_nr() pchan from the
actual ts struct, so refactor gsm_ts2chan_nr() to gsm_pchan2chan_nr() with
explicit pchan, ts_nr and lchan_nr arguments.
Change-Id: I1a40e8452fe8120d350a27973e56be0b8c8c517f
Neels Hofmeyr
