Here is a picture of a an xDSL deployment :
The BRAS is the termination for PPP sessions. The customer modem establishes a session with the BRAS, gets authenticated and can then access the ISP's network and Internet.
If I understand correctly, it is at the BRAS that the PPPoE and PPP headers will be stripped off the packet.
1) Are those headers added to packets coming from the Internet to the client before getting pushed to the DSLAM - modem, or are they only one way?
2) If they are added both ways, how does the BRAS know which session it is? Is it based on the client IP?
3) Do BRAS keep a session table, like a firewall would for an ACL or NAT for packet returns?
In short, I just want to know if the BRAS adds PPP/PPPoE headers, and doesn't just strip them off packets.