Point-to-point protocol over Ethernet

The Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating PPP frames inside Ethernet frames. It appeared shortly after the year 2000, in the context of the boom of DSL as the solution for tunneling packets over the DSL connection to the ISP's IP network, and from there to the rest of the Internet. A 2005 networking book noted that "Most DSL providers use PPPoE, which provides authentication, encryption, and compression." Typical use of PPPoE involves leveraging the PPP facilities for authenticating the user with a username and password, predominately via the PAP protocol and less often via CHAP.

On the customer-premises equipment, PPPoE may be implemented either in a unified residential gateway device that handles both DSL modem and IP routing functions or in the case of a simple DSL modem (without routing support), PPPoE may be handled behind it on a separate Ethernet-only router or even directly on a user's computer. (Support for PPPoE is present in most operating systems, ranging from Windows XP,GNU/Linux to Mac OS X.) More recently, some GPON-based (instead of DSL-based) residential gateways also use PPPoE, although the status of PPPoE in the GPON standards is marginal.