update aoip-mgw-options document with reality of 2020

This was started in 2017 before the NITB split.  Let's align it with
reality, mostly in terms of naming and making explicit what was
implemented.

Change-Id: Ib4e66b565a1edfc5ea8c1446f911011bfd4b1642

4 files changed, 33 insertions, 15 deletions

diff --git a/doc/manuals/aoip-mgw-options-docinfo.xml b/doc/manuals/aoip-mgw-options-docinfo.xml
index 080959443..4cec92fa7 100644
--- a/doc/manuals/aoip-mgw-options-docinfo.xml
+++ b/doc/manuals/aoip-mgw-options-docinfo.xml
@@ -7,6 +7,14 @@
        Initial version of the proposal for internal discussion.
     </revremark>
   </revision>
+  <revision>
+    <revnumber>1.0</revnumber>
+    <date>November 2020</date>
+    <authorinitials>Harald Welte</authorinitials>
+    <revremark>
+       Update with changes on what was actually implemented in recent years; change from future to past tense.
+    </revremark>
+  </revision>
 </revhistory>
 
 <authorgroup>
@@ -24,7 +32,7 @@
 </authorgroup>
 
 <copyright>
-  <year>2017</year>
+  <year>2017-2020</year>
   <holder>sysmocom - s.f.m.c. GmbH</holder>
 </copyright>
 
diff --git a/doc/manuals/aoip-mgw-options.adoc b/doc/manuals/aoip-mgw-options.adoc
index 124c03fda..62163ccc4 100644
--- a/doc/manuals/aoip-mgw-options.adoc
+++ b/doc/manuals/aoip-mgw-options.adoc
@@ -5,8 +5,8 @@
 This document serves as a paper to illustrate the different
 configurations of OsmoBSC in terms of integration with BTSs and MSCs.
 
-The document should accompany us in the 2017 development cycle which
-includes the _death of the NITB_, i.e. the move away from OsmoNITB to
+The document was created ahead of the 2017 development cycle which
+included the _death of the NITB_, i.e. the move away from OsmoNITB to
 having OsmoBSC in all configurations, whether with a
 proprietary/external MSC or with OsmoMSC.
 
@@ -24,8 +24,13 @@ such as
 
 === Classic GSM RAN with E1 based Abis and E1 A
 
-This configuration was actually never supported by OpenBSC, as E1 BTS
-support was so far for NITB only, but not for OsmoBSC.
+This is how GSM was originally specified when it was introduced: E1/T1
+circuits on all interfaces, no IP anywhere.
+
+This configuration was actually never supported by OpenBSC, as E1
+support was always only on the  Abis side (OpenBSC, OsmoNITB and today OsmoBSC).
+
+We never supported A interface over E1.  It could be done if there was a need.
 
 [mscgen]
 ----
@@ -53,11 +58,11 @@ Release 7 of 3GPP included an official specification on how an
 interoperable A-over-IP (AoIP) interface shall look like.
 
 As more modern MSCs at operators tend to favor implementing 3GPP AoIP
-rather than the proprietary SCCPlite based A interface, it becomes
+rather than the proprietary SCCPlite based A interface, it became
 necessary for OsmoBSC to support this.
 
 At the same time, for compatibility reasons, the classic SCCPlite
-support shall be kept, if possible with reasonable effort.
+support is kept in OsmoBSC as a configuration option.
 
 [mscgen]
 ----
@@ -65,11 +70,16 @@ include::{srcdir}/mgw/osmo-bsc-new-mgw.msc[]
 ----
 
 
-=== OsmoBSC 2017+: 3GPP AoIP + Abis/E1
+=== OsmoBSC 2020+: 3GPP AoIP + Abis/E1
+
+Since OsmoNITB was deprecated in 2017, and OsmoBSC only supported Abis/IP,
+we temporarily lost the ability to use classic E1 based BTSs.  In 2020,
+we re-introduced and re-tested the support of Abis/E1.
 
-Since OsmoNITB will soon be deprecated, we will use OsmoBSC in all
-Osmocom GSM ntework setups, requiring the support for classic E1/T1
-based BTSs from OsmoBSC.
+Fro the control plane of Abis (RSL, OML) the E1 support via libosmo-abis
+never really ceased to exist.  But for the user plane, E1 support had to be
+introduced to osmo-mgw, and osmo-bsc needed to be taught how to configure
+E1 endpoints at the MGW.  The related call flow for such setups looks like this:
 
 [mscgen]
 ----
diff --git a/doc/manuals/mgw/osmo-bsc-new-mgw-e1.msc b/doc/manuals/mgw/osmo-bsc-new-mgw-e1.msc
index 04b114fff..676948cdd 100644
--- a/doc/manuals/mgw/osmo-bsc-new-mgw-e1.msc
+++ b/doc/manuals/mgw/osmo-bsc-new-mgw-e1.msc
@@ -1,8 +1,8 @@
 # MO-Call with E1 BTS + OsmoBSC with true 3GPP AoIP (planned
-# osmo-bsc_mgcp has to be extended to true MGW functionality!
+# osmo-mgw has to be extended to true MGW functionality!
 msc {
 	hscale=2;
-	ms [label="MS"], bts [label="E1 BTS"], bsc[label="OsmoBSC"], mgcp[label="osmo-bsc_mgcp"], m_sc[label="MSC"];
+	ms [label="MS"], bts [label="E1 BTS"], bsc[label="OsmoBSC"], mgcp[label="osmo-mgw"], m_sc[label="MSC"];
 
 	ms box m_sc	[label="We assume a SDCCH is already established"];
 	...;
diff --git a/doc/manuals/mgw/osmo-bsc-new-mgw.msc b/doc/manuals/mgw/osmo-bsc-new-mgw.msc
index e618bb721..d6450bd22 100644
--- a/doc/manuals/mgw/osmo-bsc-new-mgw.msc
+++ b/doc/manuals/mgw/osmo-bsc-new-mgw.msc
@@ -1,7 +1,7 @@
-# MO-Call with OsmoBTS + OsmoBSC with true 3GPP AoIP (planned)
+# MO-Call with OsmoBTS + OsmoBSC with true 3GPP AoIP
 msc {
 	hscale=2;
-	ms [label="MS"], bts [label="OsmoBTS"], bsc[label="OsmoBSC"], mgcp[label="osmo-bsc_mgcp"], m_sc[label="MSC"];
+	ms [label="MS"], bts [label="OsmoBTS"], bsc[label="OsmoBSC"], mgcp[label="OsmoMGW"], m_sc[label="MSC"];
 
 	ms box m_sc	[label="We assume a SDCCH is already established"];
 	...;