doc: added some documentation regarding implementation and behaviour

doc/specification.md

@@ -20,10 +20,36 @@ A transaction consists of 2 nodes;
 - "Origin node"; the node who sent the origin packet.
 - "Destination node"; the node who is marked as the destination by the origin packet.
 
+## Packet terminology
+
+- "Drop"; ignore packet and OPTIONAL response.
+
 # Behaviour 
 
 This chapter describes the behaviour of a node.
 
+## Joining a network
+
+When joining a network, a node MUST send a Register Node command to `0xFFFFFFFF` (the broadcast address).  
+This ensures that all devices know of the new devices, the master node MUST respond with an appropriate reply;
+Return the same packet as response or an error.  
+
+A node MAY send a Ping command to `0xFFFFFFFF` to find other devices.  
+A node MUST reply to a Ping, if a node fails to do so the node can be considered unreachable.
+
+## Node discovery
+
+To keep network traffic less noisy ping broadcasts MAY be intercepted by the master node and the master node SHOULD send a chain of response pings as the registered devices.  
+This will ensure that the network won't get polluted with ping packets.  
+This discovery method is OPTIONAL.
+
+The traditional way is to broadcast the ping over the network and route all responses back to the origin node.
+
+## Leaving a network
+
+To gracefully leave a network a node MUST send a Remove node packet, once a reply is received the node can safely close the connection.  
+A master node MAY remove a node if the connection closes.
+
 ## Statuses
 
 When an error occurs on the destination node in result of a request, the response to the origin node MUST be a `0x0E` (error command).  
@@ -34,10 +60,26 @@ To mark a success, you MUST send back the request packet altered with the data s
 
 ### Broadcast (`0xFFFFFFFF`)
 
-Nodes MUST listen to this address.  
+This address is a broadcast address.
-Owner nodes MUST forward this address to their owners if applicable.
+All nodes MUST respond to this packet.  
+To avoid infinite loops, nodes SHOULD keep track of the `packet_id` of the broadcast packet and SHOULD drop it, if it reappears.
 
-# Packet inspection
+### Sink (`0x00000000`)
+
+This address is a sink.  
+Packets sent to this address MAY be dropped.
+
+### RECOMMENDED master node address (`0x00000001`)
+
+This address is RECOMMENDED to be used as master address.  
+
+# Implementing Domo
+
+## Extending Domo with extra commands
+
+Domo specifies commands in her protocol.  
+These MUST NOT be changed, however adding commands is OPTIONAL and allowed.  
+Nodes MAY drop unrecognised commands.
 
 ## Error checking