Introduction to PPPoE Protocol

mhkabir1952  Diamond  (1)
6 years 9 months ago  View: 793  Reply: 1

PPPoE connects an Ethernet host to a remote access concentrator via a simple bridging device. Through PPPoE, a remote access device can realize control and accounting over each accessing user. Comparing with traditional access method, PPPoE has higher performance-price ratio, thus widely assumed in a series applications including community networking, etc. It is also adopted in the currently popular broadband access mode ADSL.

PPPoE employs Client / Server mode, in which it encapsulates PPP packets into Ethernet frames and provides point-to-point connection over the Ethernet.


PPPoE has two different phases: Discovery phase and PPP Session phase.

Discovery phase

When a PPPoE Client initiates a PPP session, it must confirm the peer Ethernet MAC address through the Discovery phase and create a PPPoE session ID. Different from PPP, the Discovery phase of PPPoE creates a Client/Server relationship rather than the peer relationship created by PPP. During the Discovery phase, a PPPoE Client can discover an access concentrator (Server). After the Discovery phase, the PPPoE Client and the concentrator can establish PPPoE session via the MAC address and session ID.

PPP Session phase

At the beginning of PPP Session phase, the PPPoE Client and access concentrator transmit PPP data, perform various PPP negotiation and data transportation over PPP. PPP packets, as the payload of PPPoE frames, are encapsulated into Ethernet frames and sent to the peer of a PPPoE link. In this case, all Ethernet frames are unicast.

foisal  Gold 
6 years 9 months ago
useful