Enabling PPPoE Relay Discovery and Service Selection Functionality
First Published: May 2, 2005
Last Updated: May 4, 2009
The PPPoE Relay feature enables an L2TP access concentrator (LAC) to relay active discovery and service selection functionality for PPP over Ethernet (PPPoE), over a Layer 2 Tunneling Protocol (L2TP) control channel, to an L2TP network server (LNS) or tunnel switch (multihop node). The relay functionality of this feature allows the LNS or tunnel switch to advertise the services it offers to the client, thereby providing end-to-end control of services between the LNS and a PPPoE client.
Finding Feature Information
For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Enabling PPPoE Relay Discovery and Service Selection Functionality" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
•Prerequisites for Enabling PPPoE Relay Discovery and Service Selection Functionality
•Information About Enabling PPPoE Relay Discovery and Service Selection Functionality
•How to Enable PPPoE Relay Discovery and Service Selection Functionality
•Configuration Examples for Enabling PPPoE Relay Discovery and Service Selection Functionality
•Additional References
•Feature Information for Enabling PPPoE Relay Discovery and Service Selection Functionality
Prerequisites for Enabling PPPoE Relay Discovery and Service Selection Functionality
•You must understand the concepts described in the "Preparing for Broadband Access Aggregation" module.
•PPPoE sessions must be established using the procedures in the "Providing Protocol Support for Broadband Access Aggregation of PPPoE Sessions" module.
•This document assumes you understand how to configure a virtual private dialup network (VPDN) tunnel and a tunnel switch. See the "Related Documents" section for more information about these features.
Information About Enabling PPPoE Relay Discovery and Service Selection Functionality
To configure PPPoE relay, you need to understand the following concept:
•L2TP Active Discovery Relay for PPPoE
L2TP Active Discovery Relay for PPPoE
The PPPoE protocol described in RFC 2516 defines a method for active discovery and service selection of devices in the network by an LAC. A PPPoE client uses these methods to discover an access concentrator in the network, and the access concentrator uses these methods to advertise the services it offers.
The PPPoE Relay feature allows the active discovery and service selection functionality to be offered by the LNS, rather than just by the LAC. The PPPoE Relay feature implements the Network Working Group Internet-Draft titled L2TP Active Discovery Relay for PPPoE. The Internet-Draft describes how to relay PPPoE Active Discovery (PAD) and Service Relay Request (SRRQ) messages over an L2TP control channel (the tunnel). (See the "RFCs" section for information on how to access Network Working Group Internet-Drafts.)
The key benefit of the PPPoE Relay feature is end-to-end control of services between the LNS and a PPPoE client.
How to Enable PPPoE Relay Discovery and Service Selection Functionality
This section contains the following procedures:
•Configuring the LAC and Tunnel Switch for PPPoE Relay (required)
•Configuring the LNS (or Multihop Node) to Respond to Relayed PAD Messages (required)
•Additional References (optional)
Configuring the LAC and Tunnel Switch for PPPoE Relay
Perform this task to configure the LAC and tunnel switch for PPPoE Relay, which configures a subscriber profile that directs PAD messages to be relayed on an L2TP tunnel. The subscriber profile also will contain an authorization key for the outgoing L2TP tunnel.
SUMMARY STEPS
1. enable
2. configure terminal
3. subscriber profile profile-name
4. service relay pppoe vpdn group vpdn-group-name
5. exit
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
subscriber profile profile-name
Router(config)# subscriber profile profile-1 |
Configures the subscriber profile name and enters subscriber profile configuration mode. •profile-name—Is referenced from a PPPoE profile configured by the bba-group pppoe global configuration command, so that all the PPPoE sessions using the PPPoE profile defined by the bba-group pppoe command will be treated according to the defined subscriber profile. |
Step 4 |
service relay pppoe vpdn group vpdn-group-name
Router(config-sss-profile)# service relay pppoe vpdn group Group-A |
Provides PPPoE relay service using a VPDN L2TP tunnel for the relay. The VPDN group name specified is used to obtain outgoing L2TP tunnel information. •See the "The following example shows how to enter Subscriber Service Switch subscriber service attributes in a AAA RADIUS server profile." section for the equivalent RADIUS profile entry. |
Step 5 |
exit
Router(config-sss-profile)# exit |
(Optional) Ends the configuration session and returns to privileged EXEC mode. |
What to Do Next
Configure the LNS side of the configuration by performing the tasks described in the "Configuring the LNS (or Multihop Node) to Respond to Relayed PAD Messages" section.
Configuring the LNS (or Multihop Node) to Respond to Relayed PAD Messages
On the router that responds to relayed PAD messages, perform this task to configure a PPPoE group and attach it to a VPDN group that accepts dial-in calls for L2TP. The relayed PAD messages will be passed from the VPDN L2TP tunnel and session to the PPPoE broadband group for receiving the PAD responses.
SUMMARY STEPS
1. enable
2. configure terminal
3. vpdn-group vpdn-group-name
4. accept-dialin
5. protocol l2tp
6. virtual-template template-number
7. exit
8. terminate-from hostname host-name
9. relay pppoe bba-group pppoe-bba-group-name
10. exit
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
vpdn-group vpdn-group-name
Router(config)# vpdn-group Group-A |
Creates a VPDN group and enters VPDN group configuration mode. |
Step 4 |
accept-dialin
Router(config-vpdn)# accept-dialin |
Configures the LNS to accept tunneled PPP connections from an LAC and creates an accept-dialin VPDN subgroup. |
Step 5 |
protocol l2tp
Router(config-vpdn-req-in)# protocol l2tp |
Specifies the L2TP tunneling protocol. |
Step 6 |
virtual-template template-number
Router(config-vpdn-req-in)# virtual-template 2 |
Specifies which virtual template will be used to clone virtual access interfaces. |
Step 7 |
exit
Router(config-vpdn-req-in)# exit |
Exits to VPDN group configuration mode. |
Step 8 |
terminate-from hostname host-name
Router(config-vpdn)# terminate-from hostname LAC-1 |
Specifies the LAC hostname that will be required when the VPDN tunnel is accepted. |
Step 9 |
relay pppoe bba-group pppoe-bba-group-name
Router(config-vpdn)# relay pppoe bba-group group-2 |
Specifies the PPPoE BBA group that will respond to the PAD messages. •The PPPoE BBA group name is defined with the bba-group pppoe group-name global configuration command. •See the "RADIUS VPDN Group User Profile Entry for the LNS" section for the equivalent RADIUS profile entry. |
Step 10 |
exit
Router(config-vpdn)# exit |
Exits to global configuration mode. |
Monitoring PPPoE Relay
Perform this task to monitor PPPoE Relay.
SUMMARY STEPS
1. enable
2. show pppoe session
3. show pppoe relay context all
4. clear pppoe relay context
DETAILED STEPS
Step 1 enable
Enables privileged EXEC mode.
•Enter your password if prompted.
Step 2 show pppoe session
Displays information about currently active PPPoE sessions.
Router# show pppoe session
1 session in FORWARDED (FWDED) State
Uniq ID PPPoE RemMAC Port VT VA State
26 19 0001.96da.a2c0 Et0/0.1 5 N/A RELFWD
Step 3 show pppoe relay context all
Displays the PPPoE relay context created for relaying PAD messages.
Router# show pppoe relay context all
Total PPPoE relay contexts 1
UID ID Subscriber-profile State
Step 4 clear pppoe relay context
This command clears the PPPoE relay context created for relaying PAD messages.
Router(config)# clear pppoe relay context
Troubleshooting Tips
Use the following commands in privileged EXEC mode to help you troubleshoot the PPPoE Relay feature:
•debug ppp forwarding
•debug ppp negotiation
•debug pppoe events
•debug pppoe packets
•debug vpdn l2x-events
•debug vpdn l2x-packets
Configuration Examples for Enabling PPPoE Relay Discovery and Service Selection Functionality
This section provides the following configuration examples:
•PPPoE Relay on LAC Configuration: Example
•Basic LNS Configured for PPPoE Relay: Example
•Tunnel Switch (or Multihop Node) Configured to Respond to PAD Messages: Example
•Tunnel Switch Configured to Relay PAD Messages: Example
•RADIUS Subscriber Profile Entry for the LAC: Example
•RADIUS VPDN Group User Profile Entry for the LNS: Example
PPPoE Relay on LAC Configuration: Example
The following is an example of a standard LAC configuration with the commands to enable PPPoE relay added:
username User1 password 0 field
username User2 password 0 field
username user-group password 0 field
username User5 password 0 field
username User2-lac-domain password 0 field
username User1-client-domain@cisco.net password 0 field
username User3-lns-domain password 0 field
vpdn source-ip 10.0.195.151
vpdn-group User2-vpdn-group-domain
initiate-to ip 10.0.195.133
local name User2-lac-domain
ip address 10.22.2.2 255.255.255.0
ip address 10.0.195.151 255.255.255.0
pppoe enable group group-1
interface Virtual-Template1
ip unnumbered Loopback123
ppp chap hostname User2-lac-domain
ip route 0.0.0.0 0.0.0.0 10.0.195.1
subscriber profile Profile1
service relay pppoe vpdn group User2-vpdn-group-domain
Basic LNS Configured for PPPoE Relay: Example
The following example shows the basic configuration for an LNS with commands added for PPPoE relay:
username User5 password 0 field
username user-group password 0 field
username User1 password 0 field
username User2 password 0 field
username User3 password 0 field
username User3-dialout password 0 cisco
username User2-dialout password 0 cisco
username abc password 0 cisco
username dial-7206a password 0 field
username mysgbpgroup password 0 cisco
username User3-lns-domain password 0 field
username User2-lac-domain password 0 field
username User1-client-domain@cisco.net password 0 field
username User5-mh password 0 field
username User1@domain.net password 0 field
vpdn source-ip 10.0.195.133
! Default L2TP VPDN group
initiate-to ip 10.0.195.143
vpdn-group User3-vpdn-group-domain
terminate-from hostname User2-lac-domain
local name User3-lns-domain
relay pppoe group group-1
ip address 10.23.3.2 255.255.255.0
interface FastEthernet0/0
ip address 10.0.195.133 255.255.255.0
interface Virtual-Template2
ip unnumbered Loopback123
ip access-group virtual-access3#234 in
ppp chap hostname User3-lns-domain
ip default-gateway 10.0.195.1
ip route 0.0.0.0 0.0.0.0 10.0.195.1
Tunnel Switch (or Multihop Node) Configured to Respond to PAD Messages: Example
The following is an example of a standard tunnel switch configuration with the commands to enable response to PPPoE relay messages added:
username User1 password 0 room1
username User2 password 0 room1
username User3 password 0 room1
username User1@domain.net password 0 room1
username User3-lns-dnis password 0 cisco
username User3-lns-domain password 0 room1
username User2-lac-dnis password 0 cisco
username User2-lac-domain password 0 room1
username User5 password 0 room1
username User5-mh password 0 room1
username user-group password 0 room1
username User3-dialout password 0 cisco
username User2-dialout password 0 cisco
username abc password 0 cisco
username dial-7206a password 0 room1
username mysgbpgroup password 0 cisco
username User1-client-domain@cisco.net password 0 room1
username User4-lns-domain password 0 room1
terminate-from hostname User5-mh
relay pppoe bba-group group-1
ip address 10.4.4.2 255.255.255.0
ip address 10.3.2.2 255.255.255.0
ip address 10.0.195.143 255.255.0.0
interface Virtual-Template1
ppp chap hostname User3-lns-domain
ip default-gateway 10.0.195.1
ip route 0.0.0.0 0.0.0.0 10.0.195.1
Tunnel Switch Configured to Relay PAD Messages: Example
The following partial example shows a configuration that allows the tunnel switch to relay PAD messages:
subscriber profile profile-1
! Configure profile for PPPoE Relay
service relay pppoe vpdn group Example1.net
! Configure L2TP tunnel for PPPoE Relay
terminate-from host Host1
relay pppoe bba-group group-1
! Configure L2TP tunnel for PPPoE Relay
! PPPoE-group configured for relay
service profile profile-1
RADIUS Subscriber Profile Entry for the LAC: Example
The following example shows how to enter Subscriber Service Switch subscriber service attributes in a AAA RADIUS server profile.
Cisco:Cisco-Avpair = "sss:sss-service=relay-pppoe"
The following is an example of a typical RADIUS subscriber profile entry for an LAC:
cisco.com Password = "password"
Cisco:Cisco-Avpair = "sss:sss-service=relay-pppoe",
Tunnel-Server-Endpoint = .....,
Tunnel-Client-Auth-ID = "client-id",
Tunnel-Server-Auth-ID = "server-id",
Cisco:Cisco-Avpair = "vpdn:l2tp-tunnel-password=password",
Cisco:Cisco-Avpair = "vpdn:l2tp-nosession-timeout=never",
Tunnel-Assignment-Id = assignment-id
RADIUS VPDN Group User Profile Entry for the LNS: Example
The following example shows how to enter the VPDN group attributes in a AAA RADIUS server profile.
Cisco:Cisco-Avpair = "vpdn:relay-pppoe-bba-group=group-name"
The following is an example of a typical RADIUS subscriber profile entry for an LNS:
cisco.com Password = "password"
Tunnel-Server-Endpoint = .....,
Tunnel-Client-Auth-ID = "client-id",
Tunnel-Server-Auth-ID = "server-id",
Cisco:Cisco-Avpair = "vpdn:l2tp-tunnel-password=password",
Cisco:Cisco-Avpair = "vpdn:l2tp-nosession-timeout=never",
Cisco:Cisco-Avpair = "vpdn:relay-pppoe-bba-group=group-name"
Tunnel-Assignment-Id = assignment-id
Additional References
The following sections provide referenced related to the PPPoE Relay feature.
Related Documents
Standards
MIBs
|
|
None |
To locate and download MIBs for selected platforms, Cisco IOS XE software releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs |
RFCs
Technical Assistance
|
|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
http://www.cisco.com/techsupport |
Feature Information for Enabling PPPoE Relay Discovery and Service Selection Functionality
Table 10 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 10 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
© 2005-2009 Cisco Systems, Inc. All rights reserved.