How to Configure ISA Server to Use a PPPoE Connection

Some broadband (DSL, ADSL) Internet service providers (ISPs) require a special dial-up connection that uses Point-to-Point Protocol over Ethernet (PPPoE). This article describes how to configure Internet Security and Acceleration (ISA) Server to use this type of connection as the primary route to the internet. Please see your ISP's documentation for installation and configuration of the PPPoE software.

In this type of configuration, the ISA Server-based computer is configured with two network adapters (one on the internal network and one connected to the broadband modem) and a dial-up network adapter (the PPPoE adapter).

To properly configure ISA Server, add the dial-up entry, configure the Local Address Table (LAT), and then configure any routes to use the dial-up entry.

Part I: To Add the Dial-Up Entry to ISA Server

Some PPPoE software (such as WinPoet) are represented by a dial up entry. To configure ISA to use this entry for internet access:

1. In the ISA Management interface, expand Policy Elements.
2. Right-click Dial-up Entries, click New, and then click Dial-up Entry.
3. Type a name and description, click the PPPoE dial-up entry by clicking Select, and then specify the appropriate account information (user name and password for the PPPoE connection) by clicking Set Account.
4. Click OK.

Part II: To Construct the LAT

When you construct the LAT, include only the network adapter that represents the internal local area network (LAN). The inclusion of the network adapter that is connected to the DSL modem does not prevent network access, but it does pose a security risk on the internal network.

Part III: To Configure Routing and Firewall/SecureNAT

The final step is to ensure that both Web and Firewall/Secure NAT clients are routed through the PPPoE connection.

1. Right-click Network Configuration, click Properties.
2. Click to select Use Dial-up Entry check box.
3. Click OK.
4. Expand Network Configuration.
5. Click Routing.
6. Right-click, and then click Properties of any routes that you have configured that require access through the PPPoE adapter.
7. On the Action tab, click to select the Use dial-up entry for primary route check box.
8. Click OK.