doc: add some message sequence charts

- Connection establishment
- Connection close
- Packet transfer

doc/Makefile

@@ -1,2 +1,2 @@
 hamnet70.html: hamnet70.adoc
-	asciidoctor $<
+	asciidoctor -r asciidoctor-diagram $<

doc/hamnet70.adoc

@@ -228,12 +228,121 @@ Due to the long possible bursts, this system can achieve high throughput if ther
 === Ideas
 
 To be defined:
+
 - connection establishment procedure (request, response)
 - how do clients get an IP(v6) address? -> should be derived from the call sign
 - when are new clients allowed to connect? -> base station calls for any new stations in regular intervals
 - handling of packets from unknown clients that are not connection requests
 - signal quality handling
 
+=== Message Sequence Charts
+
+==== Connection Establishment
+
+[mermaid,format=svg,svg-type=interactive]
+.Connection establishment
+....
+sequenceDiagram
+	participant digi as Digipeater
+	participant client as Client
+
+	digi -->> client: Beacon (Broadcast)
+	digi -->> client: Beacon (Broadcast)
+	digi -->> client: Beacon (Broadcast)
+
+	Note over client: Decides to connect
+
+	client ->> digi: Connection Request
+
+	alt Connection accepted
+		digi ->> client: Connection Parameters
+		client ->> digi: Connection Acknowledgement
+		Note over digi,client: Connection established
+	else Connection rejected
+		digi ->> client: Connection Refusal
+	end
+....
+
+==== Communication during a Connection
+
+[mermaid,format=svg,svg-type=interactive]
+.In-connection communication
+....
+sequenceDiagram
+	participant digi as Digipeater
+	participant client as Client
+
+	Note over digi,client: Connection established
+
+	loop For up to 14 packets
+		digi ->> client: Packet without Transmission Request
+	end
+
+	digi ->> client: Packet with Transmission Request
+
+	Note over digi: Start timeout timer
+
+	alt Normal reply
+		loop For up to 14 packets
+			client ->> digi: Packet without Transmission Request
+		end
+
+		client ->> digi: Packet with Transmission Request
+	else Partial reply
+		loop For up to 14 packets
+			client ->> digi: Packet without Transmission Request
+		end
+
+		client --x digi: Packet with Transmission Request (lost)
+
+		Note over digi: Timeout expired
+	else No reply
+		Note over digi: Timeout expired
+	end
+
+	Note over digi: Query next client
+....
+
+==== Connection Shutdown
+
+===== Client-initiated
+
+[mermaid,format=svg,svg-type=interactive]
+.Client-initiated shutdown
+....
+sequenceDiagram
+	participant digi as Digipeater
+	participant client as Client
+
+	Note over digi,client: Connection established
+
+	Note over client: Decides to disconnect
+
+	digi ->> client: Transmission Request
+	client ->> digi: Disconnect
+
+	Note over digi,client: Connection closed
+....
+
+===== Digipeater-initiated
+
+[mermaid,format=svg,svg-type=interactive]
+.Digipeater-initiated shutdown
+....
+sequenceDiagram
+	participant digi as Digipeater
+	participant client as Client
+
+	Note over digi,client: Connection established
+
+	Note over digi: Decides to disconnect client
+
+	digi ->> client: Disconnect Request
+	client ->> digi: Disconnect
+
+	Note over digi,client: Connection closed
+....
+
 == Higher Layer Protocols
 
 [appendix]