Enterasys Networks X-PeditionTM manual PPP over Ethernet over ATM Routed, PPPoA Network Diagram

Features

Figure 13-2 PPPoA Network Diagram

PC

IP	PPPoA
Frwd	Client

PC

Router / Modem with	IP
integrated PPPoA client
	PPP
IP
	1483
Local ethernet frames
802.3	ATM
PHY
	ADSL

This implementation is restricted as follows:

•Maximum MTU of 1500 bytes

•ATM SVCs are not supported

ATM	ATM
DSL	SONET

DSLAM

Routed encapsulation - LLC/SNAP

Access

Concentrator

•Frame Relay/ATM internetworking (per FRF.8) is not supported

•PPP coding transitions - switching the method (VC-multiplexed PPP to LLC-encapsulated PPP and back) - are not supported

•PPP will not request the following LCP configuration options:

– Protocol Field Compression

– Field Check Sequence Alternatives

– Address-and-Control-Field-Compression

– Asynchronous-Control-Character-Map

PPPover Ethernet over ATM (Routed)

The XSR’s PPPoE option, as shown in Figure 13‐3, encapsulates PPP PDUs in the form of Ethernet frames which are encoded as bridged PDUs, as defined by RFC-2684. The router incorporates an integrated PPPoE client which supports the features described below:

•PPPoE encapsulation according to RFC-2516

•PPPoE session management procedures according to RFC-2516

•Bridged Ethernet PDU (802.3) encapsulation according to RFC-2684

•Statically configured and negotiated IP addresses

•Although the XSR does not support bridging protocols and operations, since most ADSL access concentrators support this encapsulation type the XSR implements the IP PDU encapsulation portion of RFC-2684 as required to enable data traffic flows. Essentially, the XSR implementation is an integrated PPPoE client supported over a router, not over a bridge as specified in RFCs 2516 and 2684. PPPoE is invoked by the encapsulation pppoe command.

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

XSR User’s Guide 13-3