13 CONFIGURING PPPOE CLIENT
This chapter contains information on the following topics:
■PPoE Overview
■Configure PPPoE Client
■Display and Debug PPPoE Client
■Typical PPPoE Configuration Example
PPoE Overview Point-to-Point Protocol over Ethernet (PPPoE) can be used for connecting Ethernet
hosts to a remote access concentrator through a simple bridging device. With
PPPoE, the remote access device can control and implement billing on the
accessed subscribers. Compared with traditional access approaches, PPPoE is more
cost-effective. Therefore, it is widely put in many applications, such as residential
quarter networks. As a popular broadband access approach at present, ADSL
(Asymmetric Digital Subscriber Line), adopts this protocol.
PPPoE adopts the client/server approach, encapsulates PPP packets in Ethernet
frames, and provides PPP connection over Ethernet.
PPPoE is implemented at two phases, the discovery phase and the PPP session
phase.
■Discovery phase
When a host initiates a PPP session, it must first go through the discovery phase
to confirm the remote Ethernet MAC address, and establish a PPPoE session ID.
Different from PPP, PPPoE establishes a c lient/server relationship at this phase,
whereas PPP establishes a peer relationship. Through the discovery phase, the
host (client) can discover an access concentrator (server). After this phase ends
normally, the host and the access concentrator can establish a PPPoE session by
using the MAC address and the session ID.
■PPP session phase
As the PPP session begins, the host and the access concentrator implement
negotiation and transmit PPP data according to PPP. The PPP packets are
encapsulated in Ethernet frames as payload of PPPoE frames, and transmitted
to the peers of the PPPoE link. In this case, all the Ethernet frames are unicast.
Refer to RFC2516 for PPPoE.
Introduction to PPPoE client
PPPoE is widely used in ADSL broadband access. Normally, if a host wants to
access the Internet via ADSL, it must have been installed with a PPPoE client
dial-up software. The 3Com Router series can work as PPPoE clients (that is,