PPPoE on Ethernet

Feature Overview
The PPPoE on Ethernet feature adds support to PPPoE by adding direct connection to actual Ethernet interfaces. PPPoE provides service-provider digital subscriber line (DSL) support. This Ethernet specification can be used by multiple hosts on a shared Ethernet interface to open PPP sessions to multiple destination with one or more bridging modems.

Benefits
Broadband Remote Access
For a bridged-Ethernet topology, this feature allows access providers to maintain session abstraction associated with PPP networks.
PPPoE
PPPoE provides the ability to connect a network of hosts over a simple bridging access device to a remote access concentrator where each host utilizes its own PPP stack. And the user gets a familiar interface.
PPPoE provides service-provider DSL support. In service-provider DSL deployments, PPPoE facilitates consumer end adoption by leveraging Ethernet scale curves and by using an embedded base.

Restrictions
The following restrictions apply when the PPPoE on Ethernet feature is used:
‧PPPoE will not be supported on Frame Relay.
‧PPPoE will not be supported on any other LAN interfaces such as FDDI and Token Ring.
‧Fast switching is supported. PPP over Ethernet over RFC 1483 fibswitching will be supported for IP. All other protocols will be switched over process switching.

Related Documents
The following are related feature modules on PPPoE:
‧PPPoE on ATM
‧PPPoE on Cable Interfaces
‧PPPoE on IEEE 802.1Q Encapsulation

Supported Platforms
This feature is supported on the following platforms:
‧Cisco 3600 series
‧Cisco 4500 series
‧Cisco 4700 series
‧Cisco 6400 series
‧Cisco 7500 series
‧Cisco MC3810 series
‧Cisco UBR 7200 series

Prerequisites
Before you can configure PPPoE on Ethernet, you need to configure a virtual private dialup network (VPDN) group using the accept dialin command, enable PPPoE, and specify a virtual template for PPPoE sessions.

Configuration Tasks
See the following sections for configuration tasks for the PPPoE on Ethernet feature. Each task in the list indicates if the task is optional or required.
Enabling PPPoE on Ethernet in a VPDN Group (Required)
Limiting PPPoE Sessions from a MAC Address (Optional)
Creating and Configuring a Virtual Template (Optional)
Specifying an Ethernet Interface (Optional)
Enabling PPPoE on an Ethernet Interface (Required)

Enabling PPPoE on Ethernet in a VPDN Group
To configure the physical interface that will carry the PPPoE session and link it to the appropriate virtual template interface, use the following commands beginning in global configuration mode:


Router(config)# vpdn enable
Router(config-if)# vpdn group name
Router(config-if)# accept dialin
Router(config-if)# protocol pppoe
Router(config-if)# virtual-template template-number


Limiting PPPoE Sessions from a MAC Address
To set the limit of sessions to be sourced from a MAC address, use the following command in VPDN configuration mode:

Router(config-if)# pppoe session-limit per-mac number


Creating and Configuring a Virtual Template
To create and configure a virtual template, use the following commands beginning in global configuration mode:

Router(config)# interface virtual-template number
Router(config-if)# ip unnumbered ethernet number
Router(config-if)# mtu bytes


Other optional configuration commands can be added to the virtual template configuration. For example, you can enable the PPP authentication on the virtual template using the ppp authentication chap command. Refer to the "Virtual Interface Template Service" chapter in the Release 12.1 Cisco IOS Dial Solutions Configuration Guide for additional information about configuring the virtual template.
Although Cisco Express Forwarding (CEF) switching is supported, flow, and optimum switching are not; these configurations are ignored on the PPP-over-Ethernet virtual access interface. CEF is enabled by default for IP. All other protocol traffic will be processed switched.

Specifying an Ethernet Interface
After you create a virtual template for PPPoE on Ethernet, specify a multipoint or point-to-point interface. To specify an Ethernet multipoint interface, use one of the following commands in global configuration mode:

Router(config)# interface ethernet interface-number


Enabling PPPoE on an Ethernet Interface
To enable PPPoE on Ethernet interfaces, use the following command in global configuration mode:

Router(config-if)# pppoe enable


Monitoring and Maintaining VPDN Groups
To monitor and maintain VPDN groups, use the following command in EXEC mode.
Router# show vpdn

Router# show vpdn session packet
Router# show vpdn session all
Router# show vpdn tunnel


Configuration Examples
This section provides the following configuration examples:
PPPoE on Ethernet Example
Enabling PPPoE on an Ethernet Interface Example

PPPoE on Ethernet Example
The following example configures PPPoE on Ethernet to accept dial-in PPPoE sessions. The virtual access interface for the PPP session is cloned from virtual template interface 1. Bridged Ethernet protocol data units (PDUs) with destination MAC addresses set to the Ethernet interface MAC address and Ethernet type set to 0x8863 are enqueued to the PPPoE discovery process. All bridged Ethernet PDUs with destination MAC addresses set to the Ethernet interface MAC address and Ethernet type set to 0x8864 coming in are forwarded to the virtual access interface associated with the PPP session.

vpdn enable
!
vpdn-group 1
accept dialin
protocol pppoe
virtual template 1
pppoe limit per-mac
!
int virtual-template 1
ip address 100.100.100.100 255.255.255.0
mtu 1492


For PPPoE virtual template interfaces, the mtu command must be configured because Ethernet has a maximum payload size of 1500 bytes, the PPPoE header is 6 bytes, and PPP Protocol ID is 2 bytes.

Enabling PPPoE on an Ethernet Interface Example
The following example enables PPPoE on an Ethernet interface:

interface ethernet1/0
pppoe enable



Command Reference
This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.

New Command
‧pppoe enable

Modified Command
‧show vpdn

pppoe enable
To enable PPP over Ethernet encapsulation (PPPoE) sessions on an Ethernet interface, use the pppoe enable global configuration command.

pppoe enable



Syntax Description
This command contains no arguments or keywords.

Defaults
No default behavior or values.

Command Modes
Global configuration

Usage Guidelines
PPPoE by default is disabled on all Ethernet interfaces.

Examples
The following example enables PPPoE sessions on Ethernet interface 1/0:

interface ethernet1/0
pppoe enable


show vpdn
To display information about active Level 2 Forwarding (L2F) Protocol tunnel and message identifiers in a virtual private dialup network (VPDN), use the show vpdn EXEC command.

show vpdn [session][packets][tunnel][all]
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