3Com 10014299 manual PPoE Overview, Introduction to PPPoE client

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 client/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,