== Running OsmoMSC

The OsmoMSC executable (`osmo-msc`) offers the following command-line
arguments:

=== SYNOPSIS

*osmo-msc* [-h|-V] [-d 'DBGMASK'] [-D] [-c 'CONFIGFILE'] [-s] [-T] [-e 'LOGLEVEL']

=== OPTIONS

*-h, --help*::
	Print a short help message about the supported options
*-V, --version*::
	Print the compile-time version number of the program
*-d, --debug 'DBGMASK','DBGLEVELS'*::
	Set the log subsystems and levels for logging to stderr. This
	has mostly been superseded by VTY-based logging configuration,
	see <<logging>> for further information.
*-D, --daemonize*::
	Fork the process as a daemon into background.
*-c, --config-file 'CONFIGFILE'*::
	Specify the file and path name of the configuration file to be
	used. If none is specified, use `osmo-msc.cfg` in the current
	working directory.
*-s, --disable-color*::
	Disable colors for logging to stderr. This has mostly been
	deprecated by VTY based logging configuration, see <<logging>>
	for more information.
*-T, --timestamp*::
	Enable time-stamping of log messages to stderr. This has mostly
	been deprecated by VTY based logging configuration, see
	<<logging>> for more information.
*-e, --log-level 'LOGLEVEL'*::
	Set the global log level for logging to stderr. This has mostly
	been deprecated by VTY based logging configuration, see
	<<logging>> for more information.


=== Multiple instances

Running multiple instances of `osmo-msc` on the same computer is possible if all
interfaces (VTY, CTRL) are separated using the appropriate configuration
options. The IP based interfaces are binding to local host by default. In order
to separate the processes, the user has to bind those services to specific but
different IP addresses and/or ports.

The VTY and the Control interface can be bound to IP addresses from the loopback
address range, for example:

----
line vty
 bind 127.0.0.2
ctrl
 bind 127.0.0.2
----

If external SMPP is enabled, you may bind it to a different interface using:

----
smpp
 local-tcp-ip 10.23.42.1 2775
----

More on SMPP configuration in <<smpp-config-global>>.

The external MNCC handler is a UNIX domain socket that is created when external MNCC handling is configured. A separate
path must be used per osmo-msc instance:

----
msc
 mncc external /tmp/mncc_socket
----

More on MNCC in <<mncc-external>>.

The SGs interface by default listens on 0.0.0.0:29118 (SCTP). Each instance of OsmoMSC must use a different IP address
and/or port. For details about the configuration of the SGs interface, see section <<sgs>>.

For the following links, OsmoMSC acts as a client and does not listen/bind to a
specific interface, and will hence not encounter conflicts for multiple instances
running on the same interface:

- The SCCP/M3UA links are established by OsmoMSC contacting an STP.
- The GSUP link is established by OsmoMSC contacting an HLR.
- The MGCP link is established by OsmoMSC contacting an MGW.


=== Configure primary links

==== Configure SCCP/M3UA to accept _A_ and _IuCS_ links

OsmoMSC acts as client to contact an STP instance and establish an SCCP/M3UA
link.

An example configuration of OsmoMSC's SCCP link:

----
cs7 instance 0
 point-code 0.23.1
 asp asp-clnt-OsmoMSC-A-Iu 2905 0 m3ua
  remote-ip 127.0.0.1
  role asp
  sctp-role client
----

This configuration is explained in detail in <<cs7_config>>.

Note that _A_ and _IuCS_ may use different SCCP instances, if so desired:

----
cs7 instance 0
 asp my-OsmoMSC-A 2905 0 m3ua
  remote-ip 10.23.42.1
  role asp
  sctp-role client
cs7 instance 1
 asp my-OsmoMSC-Iu 2905 0 m3ua
  remote-ip 10.23.42.2
  role asp
  sctp-role client
msc
 cs7-instance-a 0
 cs7-instance-iu 1
----

==== Configure GSUP to reach the HLR

OsmoMSC will assume a GSUP server (OsmoHLR) to run on the local host and the
default GSUP port (4222). Contacting an HLR at a different IP address can be
configured as follows:

----
hlr
 ! IP address of the remote HLR:
 remote-ip 10.23.42.1
 ! default port is 4222, optionally configurable by:
 remote-port 1234
----

==== Configure MGCP to connect to an MGW

OsmoMSC uses a media gateway (typically OsmoMGW) to direct RTP streams. By
default, an MGW is expected to receive MGCP requests on the IANA-registered
default port for MGCP (2427) on local host (127.0.0.1).

Here is an example configuration for a remote MGW:

----
network
 mgw 0
  remote-ip 10.9.8.7
  remote-port 2427
  reset-endpoint rtpbridge/* <1>
----
<1> The 'reset-endpoint' setting instructs the OsmoMGW to send a wildcarded
DLCX to the media gateway. This helps to clear lingering calls from the
media gateway when the OsmoMSC is restarted.

OsmoMSC is also able to handle a pool of media gateways for load
distribution. See also <<mgw_pooling>>.

[NOTE]
====
Previous versions of OsmoMSC (1.9.0 and below) didn't have the 'mgw' VTY node and
hence didn't support the MGW pooling feature. Therefore, historically the MGW
related commands where placed under the `msc` VTY node. The MGW related commands
under the  `msc` VTY are still parsed and used but its use is deprecated and
hence discouraged in favour of the new `mgw` node. Writing the config to a file
from within OsmoMSC will automatically convert the config to use the new `mgw`
node.
====