User's Manual

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BCM50a Integrated Router Configuration — Advanced
Appendix D
PPPoE
PPPoE in action
An ADSL modem bridges a PPP session over Ethernet (PPP over Ethernet, RFC
2516) from your PC to an ATM PVC (Permanent Virtual Circuit), which connects
to a DSL Access Concentrator where the PPP session terminates (see Figure 132).
One PVC can support any number of PPP sessions from your LAN. PPPoE
provides access control and billing functionality in a manner similar to dial-up
services using PPP.
Benefits of PPPoE
PPPoE offers the following benefits:
• It provides you with a familiar dial-up networking (DUN) user interface.
• It lessens the burden on the carriers of provisioning virtual circuits all the way
to the ISP on multiple switches for thousands of users. For GSTN (PSTN and
ISDN), the switching fabric is already in place.
• It allows the ISP to use the existing dial-up model to authenticate and
(optionally) to provide differentiated services.
Traditional dial-up scenario
Figure 132 depicts a typical hardware configuration in which the PCs use
traditional dial-up networking.