ZyXEL Communications Internet Security Gateway ZyWALL 2 Series User Manual page 556

ZyWALL 2 Series User's Guide
The PPPoE driver makes the Ethernet appear as a serial link to the PC and the PC runs PPP over it, while the
modem bridges the Ethernet frames to the Access Concentrator (AC). Between the AC and an ISP, the AC is
acting as a L2TP (Layer 2 Tunneling Protocol) LAC (L2TP Access Concentrator) and tunnels the PPP
frames to the ISP. The L2TP tunnel is capable of carrying multiple PPP sessions.
With PPPoE, the VC (Virtual Circuit) is equivalent to the dial-up connection and is between the modem and
the AC, as opposed to all the way to the ISP. However, the PPP negotiation is between the PC and the ISP.
ZyWALL as a PPPoE Client
When using the ZyWALL as a PPPoE client, the PCs on the LAN see only Ethernet and are not aware of
PPPoE. This alleviates the administrator from having to manage the PPPoE clients on the individual PCs.
Diagram G-2 ZyWALL as a PPPoE Client
G-2 PPPoE