BSC: Add series of message sequence charts about MGCP handling
Change-Id: Id5948677d23a58ce112b57f91bea953a93baab4c
diff --git a/doc/manuals/mgw/osmo-bsc-old-sccplite.msc b/doc/manuals/mgw/osmo-bsc-old-sccplite.msc
new file mode 100644
index 0000000..f7298bf
--- /dev/null
+++ b/doc/manuals/mgw/osmo-bsc-old-sccplite.msc
@@ -0,0 +1,64 @@
+# MO-Call with OsmoBTS + OsmoBSC using A/IP with IPA/SCCPlite
+# Supported since 2010 using osmo-bsc + osmo-bsc_nat
+msc {
+ hscale=2;
+ ms [label="MS"], bts [label="OsmoBTS"], bsc[label="OsmoBSC"], mgcp[label="osmo-bsc_mgcp"], m_sc[label="MSC"];
+
+ ms box m_sc [label="We assume a SDCCH is already established"];
+ ...;
+
+ ms -> m_sc [label="DTAP CC SETUP"];
+ ms <- m_sc [label="DTAP CC CALL PROCEEDING"];
+
+ bsc <- m_sc [label="BSSAP ASSGN REQ"];
+ bts <- bsc [label="RSL CHAN ACT"];
+ bts -> bsc [label="RSL CHAN ACT ACK"];
+ ms <-> bsc [label="Assignment"];
+ bsc -> m_sc [label="BSSAP ASSGN CMPL"];
+
+ ...;
+ bts <- bsc [label="IPA CRCX"];
+ bts box bts [label="Bind to BSC-local RTP Port"];
+ bts -> bsc [label="IPA CRCX ACK"];
+ bts <- bsc [label="IPA MDCX"];
+ bts box bts [label="Connect RTP socket to remote (bsc_mgcp) RTP Port"];
+ bts -> bsc [label="IPA MDCX ACK"];
+
+ mgcp <- m_sc [label="MGCP CRCX"];
+ mgcp box mgcp [label="Bind to BTS-local RTP Port"];
+ mgcp -> m_sc [label="MGCP CRCX OK"];
+ mgcp <- m_sc [label="MGCP MDCX (recvonly) "];
+ mgcp box mgcp [label="Connect RTP socket to remote (MSC) RTP Port"];
+ mgcp -> m_sc [label="MGCP MDCX OK"];
+ mgcp <= m_sc [label="RTP Audio"];
+ bts <= mgcp [label="RTP Audio"];
+ ms <= bts [label="Um Audio (unidirectional)"];
+ ms <- m_sc [label="DTAP CC ALERTING"];
+
+ ...;
+ mgcp <- m_sc [label="MGCP MDCX (sndrecv) "];
+ mgcp box mgcp [label="Switch to bi-directional audio"];
+ mgcp -> m_sc [label="MGCP MDCX OK"];
+ mgcp <=> m_sc [label="RTP Audio"];
+ bts <=> mgcp [label="RTP Audio"];
+ ms <=> bts [label="Um Audio (bidirectional)"];
+ ...;
+ ms <- m_sc [label="DTAP CC CONNECT"];
+ ms -> m_sc [label="DTAP CC CONNECT ACK"];
+ mgcp <- m_sc [label="MGCP MDCX (sndrecv) "];
+ mgcp box mgcp [label="Why?"];
+ mgcp -> m_sc [label="MGCP MDCX OK"];
+ --- [label="Voice Call in Progress"];
+ ms <- m_sc [label="DTAP CC DISCONNET"];
+ ms <- m_sc [label="DTAP CC RELEASE"];
+ ms <- m_sc [label="DTAP CC RELEASE COMPL"];
+ ...;
+ bsc <- m_sc [label="BSSMAP CLEAR CMD"];
+ bsc -> m_sc [label="BSSMAP CLEAR COMPL"];
+ bsc <- m_sc [label="SCCP RLSD"];
+ bsc -> m_sc [label="SCCP RLC"];
+ ...;
+ mgcp <- m_sc [label="MGCP DLCX"];
+ mgcp box mgcp [label="Release local RTP port"];
+ mgcp -> m_sc [label="MGCP DLCX OK"];
+}