Specifications

Chapter 4. Configuring Special Features 97
PPPoE (PPP over Ethernet)
PPPoE is a method of delivering PPP sessions over an Ethernet LAN connected to a DSL line, as defined in the
document RFC2516. It was designed to maintain the established PPP interface for the end user and the service
provider, while improving service through use of a DSL line.
¥ PPPoE allows the user to connect to a service provider using the same PPP interface as for a dialup
connection, but the connection is through a DSL line, which provides greater speed and bandwidth.
¥ The service provider also perceives the connection as a standard PPP session, allowing for the same access
control and billing per user as before.
¥ Multiple PPP users share the same DSL line to connect to an access concentrator.
Our router provides additional advantages to PPPoE users and service providers, as follows.
¥ Using our router, no software changes are required in the user PCs. Because the router acts as the PPPoE
client, no PPPoE software is needed in the PC.
¥ Our router acts as both the PPPoE client and as the bridge connecting the Ethernet LAN to the DSL line. It
does all IP address translation.
¥ The PPPoE client information (user name, password, and domain) are configured into the router. Once
configured, the user does not need to enter them, ever.
The following diagram illustrates how our router connects an Ethernet LAN to a service provider by serving as
both the bridge and the PPPoE client.
Configuring for PPPoE
Configuring the router for PPPoE requires that at least two remote router entries be defined in the router. One
remote router entry serves as a bridge for PPPoE traffic. The other remote router entry serves as the PPPoE client.
PPPoE Bridge
PPPoE requires a remote router entry defined for bridging. All PPPoE traffic must be bridged through the PVC or
DLCI of a remote router entry. The entry can use any protocol that supports bridging including PPP, RFC 1483, or
RFC 1490.
The remote entry must be enabled for bridging using the remote enabridge command.
The PPPoE bridge does not require the Spanning Tree Protocol. Turn off the protocol with this command:
ATM/Frame
Network
Service Provider
DSL Line
Serves as
bridge and as
PPPoE client
Ethernet LAN
User
User
User
Router
PPPoE Session
PPPoE
server