diff --git a/.obsidian/workspace b/.obsidian/workspace
index eac7b51..905262c 100644
--- a/.obsidian/workspace
+++ b/.obsidian/workspace
@@ -9,7 +9,7 @@
         "state": {
           "type": "markdown",
           "state": {
-            "file": "School/Analyse/IPV4.md",
+            "file": "School/Analyse/Network Software.md",
             "mode": "source"
           }
         }
@@ -68,7 +68,7 @@
             "state": {
               "type": "backlink",
               "state": {
-                "file": "School/Analyse/IPV4.md",
+                "file": "School/Analyse/Network Software.md",
                 "collapseAll": false,
                 "extraContext": false,
                 "sortOrder": "alphabetical",
@@ -87,15 +87,15 @@
   },
   "active": "bc6e8ad9aa0f44c3",
   "lastOpenFiles": [
-    "School/Analyse/IPV4.md",
-    "School/Analyse/Layers/3. Network Layer.md",
-    "School/Analyse/Network Hardware.md",
-    "School/Analyse/Computer Networks.md",
-    "School/Analyse/Layers/4. Transport Layer.md",
-    "School/Analyse/Layers/2. Datalink Layer.md",
-    "School/Analyse/Network Types.md",
     "School/Analyse/Network Software.md",
-    "School/Analyse/Images/distortion.png",
-    "School/Analyse/Images/noise-signal.png"
+    "School/Analyse/IPV4.md",
+    "School/Analyse/Comminucation Mediums.md",
+    "School/Analyse/Computer Networks.md",
+    "School/Analyse/Network Hardware.md",
+    "School/Analyse/Packet.md",
+    "IP-packet.png",
+    "School/Analyse/OSI Model.md",
+    "School/Analyse/Layers/3. Network Layer.md",
+    "School/Analyse/Layers/4. Transport Layer.md"
   ]
 }
\ No newline at end of file
diff --git a/IP-packet.png b/IP-packet.png
new file mode 100644
index 0000000..fe9de59
Binary files /dev/null and b/IP-packet.png differ
diff --git a/School/Analyse/IPV4.md b/School/Analyse/IPV4.md
index 0d4b6de..021ea5b 100644
--- a/School/Analyse/IPV4.md
+++ b/School/Analyse/IPV4.md
@@ -5,5 +5,10 @@
 
 IP defines datagram structure that encapsulate the data to be delivered.
 
-An IP datagram 
+An IP datagram (packet) consists of a header part an a text part. (payload)
 
+The header has a 20 byte fixed part an a variable length optional part.
+
+![[IP-packet.png]]
+
+Some of the fields in a packet are not always used.
\ No newline at end of file
diff --git a/School/Analyse/Packet.md b/School/Analyse/Packet.md
deleted file mode 100644
index e69de29..0000000