Cisco PIX PPOE Client

This is the proper recipe for connecting to an ISP that requires PPPOE authentication.

ip address outside pppoe setroute

vpdn group ISP request dialout pppoe
vpdn group ISP localname dsl-username
vpdn group ISP ppp authentication pap
vpdn username dsl-username password dsl-password

You must be using PIX IOS version 6.2 or greater for this to work.