Pppoe Overview - Avaya G250 Administration

Configuring WAN interfaces

PPPoE overview

You can configure the ETH WAN Fast Ethernet port as a WAN port using PPPoE (PPP over
Ethernet). PPPoE offers dialup style authentication and accounting and allows subscribers to
dynamically select their ISP.
PPPoE is a client-server protocol used for carrying PPP-encapsulated data over Ethernet
frames. A PPPoE client can establish a tunnel that carries PPP frames between a dialing host
(the G250/G350) and an access concentrator. This enables the use of PPP authentication
protocols (CHAP and PAP). Unlike other tunneling protocols such as L2TP and PPTP, PPPoE
works directly over Ethernet rather than IP.
A typical broadband access network is based on aDSL modems configured as transparent
Ethernet bridges. aDSL modems use ATM protocol, and the transparent bridging is done to a
well known ATM VC. On the other side of the telephone line is a device called a DSLAM. The
DSLAM terminates the aDSL physical layer, collects the ATM cells from the various aDSL
subscribers, and places them on the SP ATM infrastructure. The Ethernet frames from the
customer's host device can reach one or more access concentrators, which are the remote
access servers.
Figure 18: Typical PPPoE Network Topology
224 Administration for the Avaya G250 and Avaya G350 Media Gateways