I understand there is one to one relationship between a PPP session (client and LNS) and L2TP session (LAC and LNS). I browse the L2TP RFC and PPPoE RFC to try find out the exact establishment sequence, I can not find exact phrase that specify it.
Here is my question. When the client connects to LAC, in PPPoE, first in Discovery stage, there might not be tunnel established yet between LAC and LNS yet. The client get MAC address of the LAC, it can start send PPP packets. Since the LNS has to be logical end point of the PPP session, the client should use MAC address of LNS instead of LAC's, as the destination address.
How does this part works? LAC swap MAC address during the tunneling or, discovery has to be finished after the tunnel setup?
Can sny one give a details descriptions, perhaps refer the specfication. I assume that should specified by L2TP, I just can not find it.