insteon, what goes on at the network level?

["peter" <nospam@xxxxxxxxxx>]

Usually, the controlling device needs to be put in linking mode by holding
down a button for 3 to 10 seconds, then at the device being controlled, a
button needs to be held down for 3 to 10 seconds.

What exactly is happening at the network level at each step? Or, what
commands are sent and received?

When you press a button on a controller, what is sent? Is it a broadcast or
a one-to-one command? If it is one-to-one, since it can control more than
one device, does it send out one command per device? Meaning some device
would turn on sooner than other ones?

Is there such thing as insteon network monitor (sniffer)?