Add delays to connections

OMNeT++ allows you to easily setup a delay for any connection in Network.NED like this :

node1.my_gate <--> {delay=2s;} <--> node2.my_gate;

If you re-run your code now, you will observe a different between when the node has sent out a message and when it was received on the other side, like here in the debugging output:

Note that this delay will be applied ALWAYS, for both directions. There are more options here (only in one direction, random delay, etc.) that you can find in the OMNeT++ manual.