cellular-infrastructure
/
osmo-msc
mirror of https://gerrit.osmocom.org/osmo-msc
9
0
Fork 0
Code Issues Releases Wiki Activity

manuals: add section about the SGs interface. 

The SGs interface is currently only casually mentioned in the chapter
running, even though the SGs interface is a prominent and often
requested feature. Let's give the SGs interface its own section so that
users can find the info about it quicker.

Related: OS#6008
Change-Id: Ic7c17511ee19cb7f6d5069b27beb661ecb4b0be8
This commit is contained in:
Philipp Maier 2023-10-23 17:05:27 +02:00
parent 656354b818
commit 1759ed5709
3 changed files with 59 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
doc/manuals/chapters/running.adoc
View File

@ -74,15 +74,8 @@ msc
More on MNCC in <<mncc-external>>.
The SGs interface by default listens on 0.0.0.0:29118. Configure a different IP and/or port for each osmo-msc instance.
You may also want to configure different VLR names:
----
sgs
local-ip 127.0.0.1
local-port 29118
vlr-name vlr.example.net
----
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

55
doc/manuals/chapters/sgs.adoc Normal file
View File

@ -0,0 +1,55 @@
[[sgs]]
== SGs interface
OsmoMSC offers an SGs interface using the SGsAP protocol. The SGs interface is an
optional interface between a 2G (GERAN) / 3G (UTRAN) MSC and an 4G (EUTRAN) MME.
Its purpose is to facilitate both CSFB (Circuit-Switched Fall Back) and SMSoS
(SMS over SGs). It is used for Mobility management (MM) and paging procedures
between the EPS (Evolved Packet Services) and CS (Circuit Switched) domain.
=== VTY configuration
The SGs interface implementation in OsmoMSC is automatically active and requires
only minimal configuration. When no specific configuration is provided OsmoMSC
will listen on 0.0.0.0:29118 (SCTP) for incoming connections.
This is sufficient in the most configurations, but in larger installations,
where services are either tied to specific interfaces and/or more instances of
OsmoMSC run in parallel, a custom configuration is necessary.
The user has the option to configure the IP address (`local-ip`) and the SCTP
port (`local-port`) and also the `vlr-name` that OsmoMSC uses to identify itself
towards the MME. It should be noted that the `vlr-name` is usually the DNS name
for the IP address of the VLR/MSC, so IP address used and the `vlr-name` should
match the DNS server entry.
----
sgs
local-ip 127.0.0.1
local-port 29118
vlr-name vlr.example.net
----
In order to fine tune the behavior of the SGs interface the user also has
control over the relevant timers (`ts5`, `ts6-2`, `ts7`, `ts11`, `ts14`, `ts15`)
and counters (`ns7`, `ns11`). Each timer and counter has to be configured
separately. In the following example we change the value of ts and ns11.
----
sgs
timer ts7 23
counter ns11 100
----
[NOTE]
====
In case multiple instances of OsmoMSC run in parallel, it is advised to use a
different `vlr-name` for each instance. In any case it must be ensured that the
SGs interface of each instance is bound to a different IP address and/or port.
====
=== Connection monitoring
The user can use the VTY command `show sgs-connections` to list the MMEs that
are currently connected to OsmoMSC.

2
doc/manuals/osmomsc-usermanual.adoc
View File

@ -38,6 +38,8 @@ include::{srcdir}/chapters/osmux_msc.adoc[]
include::./common/chapters/mgwpool.adoc[]
include::{srcdir}/chapters/sgs.adoc[]
include::./common/chapters/control_if.adoc[]
include::./common/chapters/gsup.adoc[]