a short question:
do I have to use rp-pppoe, if I'm using DSL or is there any posibility to use pppd only?
I'll sleep when I'm dead
PGP pubkey on keyserver.net
pppd only knows the PPP(rotocol), but it does not know how to do that over Ethernet. rp-pppoe provides the underlying "ethernet-glue".
In short : you need both.