Features

Figure 13-1 RFC Encapsulation Layers

PPPoA

(RFC-2364)

PPPoA

(RFC-2364)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PPPoE

 

Routed

 

 

PPPoE

 

Routed

 

(RFC-2516)

 

IP

 

 

(RFC-2516)

 

IP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PPPoE

 

 

 

 

 

 

PPPoE

 

 

 

 

 

 

PPPoA

 

 

 

 

 

 

PPPoA

 

 

 

Ethernet MAC

 

 

 

 

Ethernet MAC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VC Multiplexing (RFC 1483/RFC-2684)

 

LLC/SNAP (RFC-1483/RFC-2684)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ATM AAL5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ADSL Modem

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PDU Encapsulation Choices

The XSR’s Protocol Data Unit (PDU) encapsulation choices are described and illustrated as follows.

PPP over ATM

The XSR’s PPPoA option, as defined by RFC-2364, supports the following features. The router includes an integrated PPPoA client which adds LLC/SNAP encapsulation to packets headed to the DSLAM, and strips the same from packets headed to its interior networks.

PPPoA is invoked by the encapsulation ipoa command. As shown in Figure 13-2, PPPoA supports networks running:

LLC-encapsulated PPP payload over an ATM PVC

Virtual circuit multiplexed PPP payload over an ATM PVC

Statically configured and negotiated IP addresses

Magic Number LCP configuration option

Note: Your choosing the correct PPP encapsulation method depends on the Customer Premises Equipment (CPE) support offered by your DSL provider.

13-2 Configuring ADSL

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Enterasys Networks X-PeditionTM manual PDU Encapsulation Choices, PPP over ATM