PPPoE may be handled behind it on a separate Ethernet-only router or even directly on a user’s computer. PPPoE, although the status of PPPoE in the GPON standards is marginal. Other usage scenarios are sometimes distinguished how to point a pdf to a users email tacking as a suffix another underlying transport. IP flows sharing an Ethernet infrastructure, although the lack of PPPoE switches making routing decision based on PPPoE headers limits applicability in that respect.
In late 1998, the DSL service model had a chicken-and-egg problem. ADSL technology had been proposed a decade earlier. Continuous usage throughout the workday, or even around the clock. A new model was required. Here both ISP and modem-router need to speak PPPoE. PPPoE-speaking Ethernet-only router using an Ethernet cable. A problem with creating a completely new protocol to fill these needs was time.
Several decisions were made to simplify implementation and standardization in an effort to deliver a complete solution quickly. PPPoE hoped to merge the widespread Ethernet infrastructure with the ubiquitous PPP, allowing vendors to reuse their existing software and deliver products in the very near term. WAN and ignoring the others. Implementation of such a bridge is multiple orders of magnitude simpler than a router. RFC for the same reason: the adoption period for a standards-track RFC was prohibitively long.
PPPoE was initially designed to provide a small LAN with individual independent connections to the Internet at large, but also such that the protocol itself would be lightweight enough that it wouldn’t impinge on the hoped-for home usage market when it finally arrived. PPPoE clearly succeeded in bringing sufficient volume to drive the price for service down to what a home user would pay. It remains the dominant DSL connectivity mechanism as of 2011, more than a decade later. Since traditional PPP connections are established between two end points over a serial link or over an ATM virtual circuit that has already been established during dial-up, all PPP frames sent on the wire are sure to reach the other end. But Ethernet networks are multi-access where each node in the network can access every other node. This helps the frame reach the intended destination. Hence before exchanging PPP control packets to establish the connection over Ethernet, the MAC address of the two end points should be known to each other so that they can be encoded in these control packets.
The PPPoE Discovery stage does exactly this. In addition it also helps establish a Session ID that can be used for further exchange of packets. Once the MAC address of the peer is known and a session has been established, the Session stage will start. The fifth and last step is the way to close an existing session. This PADI packet contains the MAC address of the computer sending it.
MAC address of the computer sending the PADI. The PADI packet can be received by more than one DSL-AC. Only DSL-AC equipment that can serve the “Service-Name” tag should reply. Once the user’s computer has sent the PADI packet, the DSL-AC replies with a PADO packet, using the MAC address supplied in the PADI. If more than one POP’s DSL-AC replies with a PADO packet, the user’s computer selects the DSL-AC for a particular POP using the supplied name or service. MAC address of the DSL-AC.
A PADR packet is sent by the user’s computer to the DSL-AC following receipt of an acceptable PADO packet from the DSL-AC. It confirms acceptance of the offer of a PPPoE connection made by the DSL-AC issuing the PADO packet. The PADR packet above is confirmed by the DSL-AC with a PADS packet, and a Session ID is given out with it. The connection with the DSL-AC for that POP has now been fully established. This packet terminates the connection to the POP. It may be sent either from the user’s computer or from the DSL-AC. Statements consisting only of original research should be removed.