PPPoE Circuit-Id Tag Processing

Table Of Contents

PPPoE Circuit-Id Tag Processing

vendor-tag circuit-id service

vendor-tag circuit-id strip

PPPoE Circuit-Id Tag Processing

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In an Ethernet access network, there is no unique mapping between the subscriber line identifier and the interface such as there is on a virtual circuit (VC) in an ATM-based network. The PPPoE Circuit-Id Tag Processing feature provides a way to extract a Circuit-Id tag from the digital subscriber line (DSL) as an identifier for the authentication, authorization, and accounting (AAA) access request on an Ethernet interface, thereby simulating ATM-based broadband access, but using cost-effective Ethernet instead. The tag is useful for troubleshooting the network, and is also used in RADIUS authentication and accounting processes.

Configuration Information

Configuration information is included in the "How to Configure PPPoE Circuit Id tag Processing" part of the "PPPoA, PPPoE, PPPoX" module of the Cisco IOS Broadband and DSL Configuration Guide, Release 12.4, at the following URL:

•http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hbba_c/part02/index.htm

Command Reference Information

This section documents modified commands.

•vendor-tag circuit-id service

•vendor-tag circuit-id strip

vendor-tag circuit-id service

To enable processing of the PPPoE Vendor-Specific tag in a PPPoE Active Discovery Request (PADR) packet, which extracts the Circuit-Id part of the tag and sends it to a AAA server as the NAS-Port-Id attribute in RADIUS access requests, use the vendor-tag circuit-id service command in BBA group configuration mode. To disable the command function (default), use the no form of this command.

vendor-tag circuit-id service

no vendor-tag circuit-id service

Syntax Description

This command has no argument or keywords.

Command Default

This command is disabled.

Command Modes

BBA group configuration

Command History

Release	Modification
12.4(4)T	This command was introduced.
12.2(28)SB	This command was integrated into Cisco IOS Release 12.2(28)SB.

Usage Guidelines

When this command is not enabled and the Broadband Remote Access Server (BRAS) receives a packet with the Vendor-Specific tag attached, the tag is ignored and the session is allowed to come up. The Vendor-Specific tag is extracted and processed for its Circuit-Id part when the vendor-tag circuit-id service command is enabled in BBA group configuration mode. Once the command is configured, the BRAS processes incoming PADR packets and sends the Circuit-Id tag to the AAA server as a NAS-Port-Id RADIUS attribute.

Examples

In the following example, outgoing PPPoE Active Discovery Offer (PADO) and PPPoE Active Discovery Session-confirmation (PADS) packets are configured to retain the incoming Vendor-Specific Line-Id tag:

bba-group pppoe pppoe-tag

 sessions per-mac limit 50

 vendor-tag circuit-id service

interface FastEthernet0/0.1

 encapsulation dot1Q 120

 pppoe enable group pppoe-tag

Related Commands

Command	Description
vendor-tag circuit-id strip	Removes an incoming Vendor-Specific Line-Id tag from outgoing PADO and PADR packets.

vendor-tag circuit-id strip

To remove the incoming Vendor-Specific Line-Id tag from outgoing PADO and PADR (PPPoE Active Discovery Offer and Request) packets, use the vendor-tag circuit-id strip command in BBA group configuration mode. To disable the command function (default), use the no form of this command.

vendor-tag circuit-id strip

no vendor-tag circuit-id strip

Syntax Description

This command has no arguments or keywords.

Command Default

This command is disabled.

Command Modes

BBA group configuration mode

Command History

Release	Modification
12.4(4)T	This command was introduced.
12.2(28)SB	This command was integrated into Cisco IOS Release 12.2(28)SB.

Usage Guidelines

Outgoing packets from BRAS will have a DSLAM-inserted Line-Id tag when the vendor-tag circuit-id service command is configured. DSLAM should strip the tag from the PAD outgoing packets. If the DSLAM cannot strip the tag, the BRAS must remove it before sending out the packets. When the vendor-tag circuit-id strip command is configured, the BRAS removes the incoming Vendor-Specific Line-Id tag from the outgoing packets.

Outgoing PADO and PADS packets from the BRAS will have the DSLAM-inserted Circuit-Id tag. DSLAM should strip the tag out of PADO and PADS packets. If the DSLAM cannot strip off the tag, the BRAS should remove it before sending the packets out, and this is accomplished using the vendor-tag circuit-id strip command.

Examples

In the following example, the BRAS will strip off incoming Vendor-Specific Line-Id tags from outgoing PADO and PADS packets:

bba-group pppoe pppoe-rm-tag

 sessions per-mac limit 50

 vendor-tag circuit-id service

 vendor-tag circuit-id strip 

interface FastEthernet0/0.1

 encapsulation dot1Q 120

 pppoe enable group pppoe-tag

Related Commands

Command	Description
vendor-tag circuit-id service	Enables processing of the PPPoE Vendor-Specific tag in a PADR packet so the Circuit-Id part can be sent to a AAA server as the NAS-Port-Id attribute in RADIUS access requests.