| 11.4 |  | PPPoE and the PIX Security Appliance |
| 11.4.1 |  | Overview of PPPoE |

| This section explains how the PIX Security Appliance works with Point-to-Point Protocol over Ethernet (PPPoE) in order to secure common broadband connections. It begins by explaining how PPPoE works with these broadband solutions and then discusses how the PIX has been designed to support PPPoE in these environments.

PPPoE
Broadband connections such as DSL, cable modem, and fixed wireless deliver high-speed connections that are always on, at a low cost. Many ISPs deploy PPPoE because it supports high-speed broadband access using their existing remote access infrastructure. PPPoE is also easy for customers to use.

PPPoE combines two widely accepted standards, Ethernet and PPP, to provide an authenticated method of assigning IP addresses to client systems. PPPoE is composed of two main phases:

1. Active discovery phase - In this phase, the PPPoE client locates a PPPoE server, called an access concentrator (AC). Session identification is assigned and the PPPoE layer is established.
2. PPP session phase - In this phase, PPP options are negotiated and authentication is performed. After the link setup is completed, PPPoE functions as a Layer 2 encapsulation method, allowing data to be transferred over the PPP link within PPPoE headers.