The Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating PPP frames inside Ethernet frames. It is used mainly either:
- with DSL services where a modem-router connects to the DSL service and sends Internet traffic over PPPoE. Note that the PPPoE over DSL side of things is occasionally referred to as "PPPoE over ATM" (PPPoEoA); or,
- when a DSL modem is connected to a (residential) router using an Ethernet cable.
Older types of link used for connecting modems to PCs or to routers, RS232 and then USB 1.1, are not fast enough to handle DSL services, so by the mid 1990s a new type of link was urgently needed (this being some years before the arrival of USB 2.0), and PPPoE became the solution for tunneling packets over the DSL connection to the ISP's IP network, and from there to the reset of the Internet.
PPPoE was developed by UUNET, Redback Networks and RouterWare (now Wind River Systems) and is available as an informational RFC 2516.
Read more about Point-to-point Protocol Over Ethernet: Original Rationale, Looking Forward, Protocol Overhead, How PPPoE Fits in The DSL Internet Access Architecture, PPPoE Discovery (PPPoED), Quirks