7-32
ADSL WAN Connections
PPPoE Overview
Step 4. When the access concentrator receives the PADR frame, it checks
the service name tag. If it accepts the service name tag, the access
concentrator generates a unique session ID. It includes this ID and the service
name tag in a PPPoE Active Discovery Session-confirmation (PADS) frame
and sends this frame to the PPPoE client.
If the access concentrator rejects the service name tag included in the PADR,
it sends a PADS frame that includes a service-name error tag and a session ID
of 0x0000. This signals to the PPPoE client that the access concentrator cannot
provide that service.
PPP Session
After the PPPoE client receives the PADS frame, the PPP session begins, and
the two devices begin exchanging frames in the customary sequence for PPP.
The devices exchange the PPP frames in the order shown in Figure 7-10.
Figure 7-10. Establishing a PPP Session
Step 1. The devices exchange link control protocol (LCP) frames to estab-
lish, configure, and control the link.
Step 2. If the devices are configured for authentication, they use one of the
following protocols to verify that they are establishing a session with the
correct PPP peer: Password Authentication Protocol (PAP), Challenge Hand-
shake Authentication Protocol (CHAP), or Extensible Authentication Proto-
col (EAP). Exchanging authentication frames is optional.
The ProCurve Secure Router supports PAP and CHAP. For more information
about configuring PPP authentication on the ProCurve Secure Router, see
“PPP Authentication” on page 6-72 in Chapter 6: Configuring the Data Link
Layer Protocol for E1, T1, and Serial Interfaces.
1. Link establishment
LCP
2. Authentication (optional)
PAP, CHAP, or EAP
3. Negotiation of network layer protocols
NCP: IPCP, BCP, IPXCP, and so on
4. Session established
PPP
Router
Access
concentrator
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