What is PPPoE?
PPPoE (Point to Point Protocol over Ethernet) is a network protocol that allows data communication between two entities or points. PPPoE expands more than the original capability of PPP by allowing a virtual point to point connection over multipoint Ethernet network architecture.
Since PPP and PPPoE are similar, PPPoE is widely used by ISPs to provide high speed Internet services like DSL (Digital Subscriber Line). PPPoE is configured as a point to point connection between two Ethernet ports. PPPoE session is initiated by connection software on the client machine or router.
PPPoE session initiation involves the identification of the MAC address (Media Access Control) of the remote device, this process is called PPPoE discovery, involves the following steps:
1) Initiation Step – The software on the client machine sends a PADI (PPPoE Active Discovery Initiation) packet to the server to initiate the session.
2) Offer Step – The server will respond with a PADO (PPPoE Active Discovery Offer) packet.
3) Request Step – After receiving the PADO, the client will respond by sending a PADR (PPPoE Active Discovery Request) packet to the server.
4) Confirmation Step – After receiving PADR, the server will respond by generating a unique ID for PPP session and send it as PADS (PPPoE Active Discovery Session) confirmation packet to the client.
After a PPPoE session was initiated, the destination IP address is only used when the session is still active. After the session is closed the IP address is released, and this allows efficient re-use of IP address.