While learning for my IT Security exam I wonder why PPPoE is used for establishing DSL connections instead of EAPoL?
In PPPoE, the authentication is embedded in PPP frames, which are embedded in PPPoE frames, which are embedded in Ethernet frames. As authentication protocols, PAP, CHAP or EAP is used (EAP is the best one).
EAPoL directly embedds the EAP packets in Ethernet frames and thus also provide authentication with much less overhead.
Which additional features does PPP/PPPoE provide that are needed for DSL connections? Is it related to the discovery of the network authentication server or because of the backward compatibility to PAP/CHAP ?