manual: It's not "A over SCCP" but "BSSAP over SCCP"

In GSM specs, the entire interface between two elements is designated
with some letter, like the A interface between BSC and MSC.  The
interface uses a variety of protocols stacked on each other.

In the specific case of A, there is no "A" on top of SCCP, but
there's "BSSAP" on top of SCCP.

This is followed somewhat un-orthodox by 3GPP, as "A over IP" is
a violation of that principle.  It should have been called "A utilizing
IP", "A based on IP", "A with IP" or something the like.

In any case, at no point do the specs ever claim that "A" is stacked
on top of SCCP, so let's fix this.

Change-Id: Ieb0d8f6c71debe1234aff343a994c2096326da1b

1 files changed, 14 insertions, 14 deletions

diff --git a/doc/manuals/chapters/overview.adoc b/doc/manuals/chapters/overview.adoc
index 9b619fb24..d3deb276d 100644
--- a/doc/manuals/chapters/overview.adoc
+++ b/doc/manuals/chapters/overview.adoc
@@ -38,20 +38,20 @@ OsmoBSC implements a sub-set of the GSM A interface as specified in TS 08.08
 
 Osmocom offers two variants of the 'A' interface's protocol stacking:
 
-- 'A/SCCPlite'
-- 'A/SCCP/M3UA'
+- 'BSSAP/SCCPlite'
+- 'BSSAP/SCCP/M3UA'
 
-Traditionally, OsmoBSC only implemented the A/SCCPlite protocol, but since a
+Traditionally, OsmoBSC only implemented the BSSAP/SCCPlite protocol, but since a
 proper M3UA implementation is available from 'libosmo-sigtran'
-('libosmo-sccp.git'), the stock OsmoBSC now supports only A/SCCP/M3UA. (The
+('libosmo-sccp.git'), the stock OsmoBSC now supports only BSSAP/SCCP/M3UA. (The
 idea is that SCCPlite support may be added to libosmo-sigtran at some point
 in the future, after which the new `osmo-bsc` would support both variants of
 the A interface.)
 
-The difference between an A/SCCPlite and A/SCCP/M3UA is illustrated in
+The difference between an BSSAP/SCCPlite and BSSAP/SCCP/M3UA is illustrated in
 <<fig-sccplite>> and <<fig-sccp-m3ua>>.
 
-===== A/SCCPlite
+===== BSSAP/SCCPlite
 
 Unlike classic A interface implementations for E1 interfacs,
 `osmo-bsc-sccplite` implements a variant of encapsulating the A interface over
@@ -60,12 +60,12 @@ communicated over TCP.  The audio channels are mapped to RTP streams.
 
 This protocol stacking is sometimes called "SCCPlite".
 
-At the time of writing, if you would like to use the old A/SCCPlite protocol,
+At the time of writing, if you would like to use the old BSSAP/SCCPlite protocol,
 look for binary packages named `osmo-bsc-sccplite`, or compile `osmo-bsc` from
 the 'openbsc.git' repository.
 
 [[fig-sccplite]]
-.`osmo-bsc-sccplite` operation using 'A/SCCPlite'
+.`osmo-bsc-sccplite` operation using 'BSSAP/SCCPlite'
 [graphviz]
 ----
 digraph G {
@@ -81,24 +81,24 @@ digraph G {
         {MS0,MS1}->BTS0 [label="Um"];
         {MS2,MS3}->BTS1 [label="Um"];
         {BTS0,BTS1}->BSC [label="Abis\nTCP\nIP"];
-        BSC->MSC [label="A\nSCCP\nTCP\nIP"];
+        BSC->MSC [label="BSSAP\nSCCP\nTCP\nIP"];
 }
 ----
 
-===== A/SCCP/M3UA
+===== BSSAP/SCCP/M3UA
 
 The default OsmoBSC's A interface uses the M3UA variant of SIGTRAN protocol
 stacking:
 
 |=====
-|A
+|BSSAP
 |SCCP
 |M3UA
 |SCTP
 |IP
 |=====
 
-To use the now-default A/SCCP/M3UA protocol, look for binary packages named
+To use the now-default BSSAP/SCCP/M3UA protocol, look for binary packages named
 `osmo-bsc`, or compile `osmo-bsc` from the 'osmo-bsc.git' repository. It is
 recommended to use the M3UA variant, which is required to operate with OsmoMSC.
 
@@ -106,7 +106,7 @@ To route SCCP/M3UA messages between OsmoBSC and and MSC, an STP instance like
 OsmoSTP is required.
 
 [[fig-sccp-m3ua]]
-.`osmo-bsc` operation using 'A/SCCP/M3UA'
+.`osmo-bsc` operation using 'BSSAP/SCCP/M3UA'
 [graphviz]
 ----
 digraph G {
@@ -123,7 +123,7 @@ digraph G {
         {MS0,MS1}->BTS0 [label="Um"];
         {MS2,MS3}->BTS1 [label="Um"];
         {BTS0,BTS1}->BSC [label="Abis\nTCP\nIP"];
-        BSC->STP->MSC [label="A\nSCCP\nM3UA\nSCTP\nIP"];
+        BSC->STP->MSC [label="BSSAP\nSCCP\nM3UA\nSCTP\nIP"];
 }
 ----