PPoE requires certain signals and information to establish, accept,
control and terminate the session. The basic signalling is shown below.
A PADI (PPPoE Active Discovery Initiation) broadcast signal is sent by the host to the remote devices.
A PADO (PPPoE Active Discovery Offer) signal is sent by the remote device back to the host.
A PADR (PPPoE Active Discovery Request) unicast signal is sent by the host to the remote device.
A PADS (PPPoE Active Discovery Session-Confirmation) is sent by the remote device back to the host.
A PADT (PPPoE Active Discovery Terminate)
signal is sent to terminate a PPPoE session. It is the proper way to
terminate a session but is not the actual cause for the termination. The
cause may be a simple timeout, a manual request by either end, or an
out of spec line condition.
