From 69682352786a7e276c695d9b274bd353025a5e4e Mon Sep 17 00:00:00 2001
From: Neels Hofmeyr <neels@hofmeyr.de>
Date: Sun, 18 Jul 2021 12:49:18 +0200
Subject: [PATCH] call_reestablishment.ladder

Change-Id: I4da8b8b37a874975f4eb1e633bc114e606b27f1e
---
 .gitignore                                    |  2 ++
 .../call_reestablishment.ladder               | 36 +++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 doc/sequence_charts/call_reestablishment.ladder

diff --git a/.gitignore b/.gitignore
index eaff7cd47..8c857c317 100644
--- a/.gitignore
+++ b/.gitignore
@@ -75,3 +75,5 @@ doc/manuals/common
 doc/manuals/build
 
 contrib/osmo-msc.spec
+
+doc/sequence_charts/call_reestablishment.msc
diff --git a/doc/sequence_charts/call_reestablishment.ladder b/doc/sequence_charts/call_reestablishment.ladder
new file mode 100644
index 000000000..ccf834622
--- /dev/null
+++ b/doc/sequence_charts/call_reestablishment.ladder
@@ -0,0 +1,36 @@
+{hscale=2}
+ms = MS
+cell1 = Cell 1 (BTS+BSC)
+cell0 = Cell 0 (BTS+BSC)
+msc = MSC
+
+ms () msc	Call Re-Establishment
+ms [] msc	Ongoing voice call: MM is established
+
+...
+
+ms ->< cell0	radio link fails
+ms ><- cell0
+
+msc <> .	Keep MM until timeout
+
+ms -> cell1	Channel Required
+ms <- cell1	Immediate Assignment
+ms -> cell1	Complete Layer3
+cell1 -> msc	Complete Layer3:
+		CM Re-Establishment Request
+
+cell0 <- msc	Clear Command
+cell0 -> msc	Clear Complete
+
+cell1 <- msc	Authentication Request
+cell1 -> msc	Authentication Response
+
+cell1 <- msc	Cipher Mode Commad
+cell1 -> msc	Cipher Mode Complete
+
+cell1 <- msc	Assignment Request
+		this Assignment ACKs the CM Re-Establishment
+ms <- cell1	RR Assignment Command
+ms -> cell1	RR Assignment Complete
+cell1 -> msc	Assignment Complete