Point-to-Point Protocol (PPP)
PPP is a layer 2 protocol for carrying IP traffic over a direct link between two nodes, with authentication and address assignment.
What is Point-to-Point Protocol (PPP)?
Broadband commonly uses PPP over Ethernet (PPPoE) or ATM (PPPoA): the user's router logs in to the provider's BRAS, which authenticates it and assigns an IP address.