PPPoE/v6 Administrator's Guide

Introduction
Software Architecture
Chapter 116
Software Architecture
Figure 1-4 illustrates the architecture of the PPPoE software.
Figure 1-4 PPPoE Architecture
The numbers 1,2,3,4, and 5, in Figure 1-4, depict the interactions
between the client and the server before and after establishing a PPPoE
connection. See “PPPoE Overview,” on page 11‚ for more information.
The PPPoE client initially searches for an access concentrator in a
separate process, which forks a pppd process on discovering the
appropriate server. It also notifies the pppd process that the basic device
is Ethernet. Several pppd processes may be running on the server,
waiting for PPPoE packets.
When a client sends a packet, all the pppd processes running on the
server receive it and filter it based on the session ID within the PPPoE
packet. A multiplexor (MUX) installed on the server prevents all the
pppd processes from receiving the packet. The multiplexor is linked to a
Client
pppd
dlpi
PPPoE
Server
pppd pppd
dlpi
MUX
1
PADI
PADO
2
3
PADR
5
PADS
4
PADT