Change in osmo-gsm-manuals[master]: add common/chapters/cs7-config

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neels gerrit-no-reply at lists.osmocom.org
Tue Mar 17 23:59:40 UTC 2020


neels has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/17502 )


Change subject: add common/chapters/cs7-config
......................................................................

add common/chapters/cs7-config

This will be used by the manuals of osmo-bsc, osmo-hnbgw, osmo-msc.

Related: OS#2767
Change-Id: Ia2508d4c7b0fef9cdc57e7e122799a480e340bf7
---
A common/chapters/cs7-config.adoc
1 file changed, 226 insertions(+), 0 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-gsm-manuals refs/changes/02/17502/1

diff --git a/common/chapters/cs7-config.adoc b/common/chapters/cs7-config.adoc
new file mode 100644
index 0000000..61efad9
--- /dev/null
+++ b/common/chapters/cs7-config.adoc
@@ -0,0 +1,226 @@
+[[cs7_config]]
+== Configure SCCP/M3UA
+
+All CNI programs using SCCP/M3UA act as client to connect to an STP instance.
+The STP then routes SCCP messages between its clients, typically by
+point-codes.
+
+For example,
+
+- OsmoMSC contacts an OsmoSTP and subscribes its point-code 0.23.1;
+- then OsmoBSC also contacts the same OsmoSTP, subscribes with its own
+  point-code 1.23.3.
+- Using these established links, OsmoBSC initiates an A-interface link by
+  directing a BSSAP RESET message to the MSC's point-code 0.23.1,
+- and the RESET ACK response from the MSC is routed back to the BSC's
+  point-code 1.23.3.
+
+The details of SCCP/M3UA are configured in the 'cs7' section of the VTY
+configuration.
+
+Osmocom programs automatically configure missing SCCP/M3UA configuration, by
+assuming sane defaults.
+
+If no explicit `routing-key` is set, it may be determined at runtime by
+negotiation with OsmoSTP -- see OsmoSTP manual chapter "Osmocom M3UA Routing
+Key Management Extensions", regarding config option `accept-asp-connections
+dynamic-permitted`.
+
+The complete active configuration of an Osmocom program can be obtained by the
+VTY command `show cs7 config` (the usual `show running-config` omits
+automatically configured items). Here is an example of OsmoMSC's default
+configuration:
+
+----
+OsmoMSC> show cs7 config
+cs7 instance 0
+ point-code 0.23.1
+ asp asp-clnt-OsmoMSC-A-Iu 2905 0 m3ua
+  remote-ip 127.0.0.1
+  sctp-role client
+ as as-clnt-OsmoMSC-A-Iu m3ua
+  asp asp-clnt-OsmoMSC-A-Iu
+  routing-key 2 0.23.1
+----
+
+At the time of writing, SCCP/M3UA links involving Osmocom program are:
+
+- A-interface: OsmoBSC to OsmoMSC
+- IuCS-interface: OsmoHNBGW to OsmoMSC
+- IuPS-interface: OsmoHNBGW to OsmoSGSN
+
+=== Connect to STP Instance
+
+By default, an STP instance is assumed to listen on the default M3UA port
+(2905) on the local host (127.0.0.1).
+
+Establishing an SCCP/M3UA link towards a remote STP instance can be configured
+as:
+
+----
+cs7 instance 0
+ asp my-asp 2905 0 m3ua
+  # IP address of the remote STP:
+  remote-ip 10.23.24.1
+----
+
+Be aware that such an `asp` needs to be linked to an `as`, see <<as_and_asp>>.
+
+[[point_code_format]]
+=== Point-Code Format
+
+Point-codes can be represented in various formats. For details, see OsmoSTP
+manual, chapter "Point Codes".
+
+By default, Osmocom uses a point-code representation of 3.8.3, i.e. first digit
+of 3 bit, second digit of 8 bit, and third digit of 3 bit.
+
+----
+cs7 instance 0
+ point-code format 3 8 3
+ point-code 0.23.1
+----
+
+Often, point-codes are also represented as a single decimal number:
+
+----
+cs7 instance 0
+ point-code format 24
+ point-code 185
+----
+
+It is also possible to use a dash as delimiter.
+
+----
+cs7 instance 0
+ point-code delimiter dash
+ point-code 0-23-1
+----
+
+
+=== Local Point-Code
+
+Each CNI program on an SCCP/M3UA link typically has a local point-code,
+configurable by:
+
+----
+cs7 instance 0
+ point-code 7.65.4
+----
+
+If an explicit routing context is configured, this point-code is repeated in
+the `routing-key` configuration:
+
+----
+cs7 instance 0
+ point-code 0.23.1
+ as my-as m3ua
+  routing-key 2 0.23.1
+----
+
+See also <<point_code_format>>.
+
+=== Remote Point-Code
+
+Programs establishing communication across SCCP links need a remote SCCP
+address, typically by point-code, to contact.
+
+For example,
+
+- OsmoBSC needs to know the MSC's point-code, to be able to establish the A-interface.
+- OsmoHNBGW needs to know the MSC's point-code, to be able to establish the IuCS-interface.
+- OsmoHNBGW needs to know the SGSN's point-code, to be able to establish the IuPS-interface.
+
+To maintain remote SCCP addresses, each `cs7` instance maintains an SCCP address book:
+
+----
+cs7 instance 0
+ sccp-address my-entry
+  point-code 1.23.1
+----
+
+This address book entry on its own has no effect. It is typically referenced by
+specific configuration items depending on the individual programs.
+
+Examples:
+
+- An OsmoBSC configures the MSC's remote SCCP address:
+
+----
+cs7 instance 0
+ sccp-address my-remote-msc
+  point-code 1.23.1
+msc 0
+ msc-addr my-remote-msc
+----
+
+- An HNBGW configures both the remote MSC's and SGSN's SCCP addresses:
+
+----
+cs7 instance 0
+ sccp-address my-msc
+  point-code 0.23.1
+ sccp-address my-sgsn
+  point-code 0.23.2
+hnbgw
+ iucs
+  remote-addr my-msc
+ iups
+  remote-addr my-sgsn
+----
+
+Besides a point-code, an SCCP address can have several routing indicators:
+
+- PC: routing by point-code is the default for Osmocom.
+- GT: routing by Global Title is configurable by `routing-indicator GT`.
+- IP: routing by IP address is configurable by `routing-indicator IP`.
+
+In OsmoSTP, only routing by point-code is currently implemented.
+
+[[as_and_asp]]
+=== AS and ASP
+
+Each CNI program needs an Application Server `as` and Application Server
+Process `asp` configured on its `cs7` to be able to communicate on SCCP/M3UA.
+An `asp` is part of an `as`. For details, see the OsmoSTP manual, chapters
+"Application Server" and "Application Server Process".
+
+In Osmocom's `cs7`, any amount of `as` and `asp` can be configured by name, and
+an `as` references the `asp` belonging to it by their names.  In typical usage,
+an Osmocom program will have exactly one `as` with one `asp`.
+
+For example:
+
+----
+cs7 instance 0
+ asp my-asp 2905 0 m3ua
+  # where to reach the STP:
+  remote-ip 127.0.0.1
+  sctp-role client
+ as my-as m3ua
+  asp my-asp
+----
+
+It is possible to configure only an `as` or only an `asp` explicitly -- a
+missing entity will be configured automatically. However, be aware that when
+both are configured manually, they need to be linked by name. For example, the
+following configuration will *fail*, because `as` and `asp` are not linked:
+
+----
+cs7 instance 0
+ asp my-asp 2905 0 m3ua
+  remote-ip 127.0.0.1
+ as my-as m3ua
+  routing-key 2 0.23.1
+----
+
+To *fix* above config, link the `asp` to an `as` by adding `asp my-asp`:
+
+----
+cs7 instance 0
+ asp my-asp 2905 0 m3ua
+  remote-ip 127.0.0.1
+ as my-as m3ua
+  asp my-asp
+  routing-key 2 0.23.1
+----

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Gerrit-Project: osmo-gsm-manuals
Gerrit-Branch: master
Gerrit-Change-Id: Ia2508d4c7b0fef9cdc57e7e122799a480e340bf7
Gerrit-Change-Number: 17502
Gerrit-PatchSet: 1
Gerrit-Owner: neels <nhofmeyr at sysmocom.de>
Gerrit-MessageType: newchange
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